Planet Musings

October 23, 2026

John Preskill — Nicole’s guide to writing and editing

Freshman year of college, I took a writing seminar from German-literature professor Ellis Shookman. Professor Shookman loved Mozart’s music, he told us early in the term. He listened to Mozart on the radio while driving from campus to Boston. Static might mar the transmission, but he could often turn up the volume and continue enjoying the program. Sometimes, the static worsened during the drive. It could worsen and worsen, until Professor Shookman’s frustration outweighed his delight at listening. He’d switch off the radio.

As Professor Shookman loved listening to Mozart’s music, he loved reading about students’ ideas. Yet static can mar a piece of writing: infelicities in grammar, structure, composition, word choice, and more. If enough infelicities obscure the writing, the frustration of reading outweighs the benefits. Professor Shookman will quit reading.

Professor Shookman marked up our essays with a blue pencil that achieved the status of legend among his students. If you’ve written a paper I’ve coauthored, you’ve probably received PDF drafts replete with green highlighting.1 A sticky note explains the reason for each highlighting: “Singular–plural mismatch.” “Active voice >> passive voice.” “Let’s clue the reader in as to this formula’s meaning before lobbing the math at them.” 

Over the past year, I’ve catalogued the suggestions I write most often on paper drafts. The comments embody principles gleaned from Strunk and White’s The Elements of Style; the Physical Review style guide; other writing guides I esteem; literature whose writing I esteem;2 collaborations with professional editors; and writing instructors, including Professor Shookman. Each section below begins with more-important principles, shading into more-nuanced ones.

Please use and disseminate these principles. Train your favorite large-language model (LLM) on them, and have the LLM critique your manuscripts. Instruct it to use green highlighting if you wish. Even if the LLM suggests fixes initially, tell it to stop offering suggestions later, so that you can devise the solutions: train not only the LLM, but also yourself. I hope to enjoy your papers as much as Professor Shookman enjoyed his sonatas.

  1. Organization
    1. Motivate your work; then, present it; and then, explain its physical significance.
    2. Begin each paragraph with a topic sentence.
    3. Begin each section, apart from the introduction and conclusion, with (i) a statement of the takeaway and (ii) an outline of the section. When outlining a section, hyperlink to each subsection. Similar guidelines concern subsections and subsubsections.
    4. Before presenting a piece of math, sketch its meaning and origin. This strategy enables the reader to understand the math as soon as they encounter it. If you throw math at the reader without introducing it, the reader will have to squint at the symbols for a while to figure out what the expression means and where it comes from.
      • Example: To calculate the average work, we substitute the Hamiltonian formula (10) into the definition (12): [equation].
    5. Most citations belong at the ends of (i) sentences and (ii) phrases concluded with commas. Put a citation elsewhere only if you have a compelling reason for doing so.
    6. Bridge each component of your writing to the next component; the next shouldn’t sound like a non sequitur.
      • Suppose that the next sentence refers to (i) a topic mentioned in the previous sentence and (ii) a new topic. Mention (i) before (ii).
        • Example: Smith et al. applied control theory to the extent possible. The attempt led to intractable equations, unlike our approach.
        • Example of a broken bridge: Smith et al. applied control theory to the extent possible. Our approach does not involve intractable equations, unlike theirs.
    7. Whenever you tell a story, tell it from start to finish, step by step. Derivations, proofs, and descriptions of experiments qualify as stories.
      • This guideline extends to descriptions of experimental setups and of mathematical objects. For example, imagine referring to an element of a subgroup of the group generated by some operators. Did you have to read the preceding sentence multiple times to process it? The sentence begins at the end of a story, then rewinds to the story’s beginning. This structure impedes understanding. The subgroup forms the context for the subgroup element, which one can’t grasp until hearing about the subgroup. The subgroup participates in a similar relationship with the group, as does the group with its generators. Therefore, one should introduce the generators, then the group, then the subgroup, and then the subgroup element.
  2. Word choice
    1. Use strong, specific words, rather than weak words.
      1. Verbs and nouns are stronger than adjectives and adverbs.
      2. Choose specific verbs (e.g., “prepare,” “evolve,” and “measure”), rather than vague, general verbs (e.g., variants of “to be” and “take,” as in “take a measurement”).
    2. Avoid statements such as “we investigate,” “we study,” and “we analyze.” Such statements don’t relate that you’ve accomplished anything. State what you’ve accomplished. Verbs such as “prove,” “test,” “confirm,” “discover,” and “find” achieve this goal.
    3. Adverbs such as “importantly” and “remarkably” pollute scientific writing with the authors’ opinions. Demonstrate that a claim is important or that a result is remarkable; then, leave readers to draw their own conclusions. Those conclusions will coincide with yours if you’ve demonstrated your point.
    4. Use the active voice, rather than the passive voice. Take responsibility for your work. Editors of high-impact scientific journals have endorsed this advice.
    5. Refer to yourself when necessary and only when necessary.
      • Example of unnecessary reference to self: We use the superscript “max” to signify the maximal Fisher information.
        Preferable alternative: The superscript “max” signifies the maximal Fisher information.
      • Example of unnecessary reference to self: Our results establish several opportunities for future research. First, we can implement the experimental proposals.
        Preferable alternative: Our results establish several opportunities for future research. First, one can implement the experimental proposals.
      • You may use the first-person plural when escorting the reader through a derivation.
        • Example: We substitute from Eq. (1) into Eq. (2).
    6. If you’re the only author, don’t use the plural (“we,” “our,” etc.). The usage is inaccurate and misleading. It portrays you as dodging responsibility for your work by dispersing that responsibility across the scientific community.
    7. Avoid dangling modifiers.
    8. Pair every verb with the appropriate noun.
      • Example of grammatically incorrect text: Equation (1) follows by calculating the sum.
        • One should pair the verb “calculate” with the noun “we,” because “we” undertook the calculating. However, this example’s author omitted the noun out of squeamishness about using the first person in a scientific document. Hence the sentence says that the equation calculates the sum. Equations can’t calculate sums.
      • Examples of correct alternatives
        • We derived Eq. (1) by calculating the sum.
        • Equation (1) follows from the evaluation of the sum.
        • Calculating the sum yields Eq. (1).
    9. Avoid empty subjects.
    10. Include no unnecessary words.
      1. “So-called” is unnecessary.
      2. “Note that” and “We note that” are unnecessary.
      3. Several phrases often preface mathematical statements but are unnecessary: “we have,” “we have that,” “it holds that,” and “it follows that.” One can better serve the reader by prefacing the mathematical statement with (i) a derivation or (ii) a prose description of the statement.
      4. Never write “is equal to”; “equals” is more concise.
      5. Never write “is able to”; “can” is more concise.
      6. Never write “gives an upper bound to” or “places an upper bound on”; “upper-bounds” is more concise. Analogous statements concern lower bounds.
      7. Never write “a large number of”; “many” is more concise. Never write “a small number of”; “few” is more concise.
      8. Never write “We refer to [symbol] as [name]”; “we call [symbol] [name]” is more concise.
      9. Never write “as long as”; “if” is more concise.
      10. Never write “a single”; “one” is more concise.
      11. The symbol > means “greater than”; and \geq, “greater than or equal to.” Don’t translate > into “strictly greater than”; the “strictly” is unnecessary. Analogous statements concern < and \leq.
    11. Avoid contractions, which are too informal for professional writing.
    12. The possessive is not a contraction and belongs in professional writing. It facilitates conciseness.
    13. Use the word “for” only when it belongs. Physicists often write “for” when they mean “if,” “per,” “at,” or something else.
      • Example of inappropriate use: The function vanishes for odd arguments.
        Corrected statement: If the argument is odd, the function vanishes.
      • Example of inappropriate use: We performed 10 trials for each parameter value.
        Corrected statement: We performed 10 trials per parameter value.
      • Example of inappropriate use: The function is smaller for small x values.
        Corrected statement: The function is smaller at small x values.
    14. Write “we evolve the state,” “we measure,” etc. only if you’re an experimentalist who undertakes those actions. Alternatives include “Consider measuring,” “Suppose the system evolves,” and the command tense (e.g., “One can measure this quantity as follows: prepare the qubit in \lvert 0\rangle. Evolve it under H…”).
    15. The condition x\ll y defines a regime, not a limit. The conditions \lim_{x\to0} and \lim_{y\to\infty} define limits and are inequivalent to x\ll y.
    16. Write “first,” “second,” “last,” etc., not “firstly,” “secondly,” “lastly,” etc. (I defer in this matter to The Elements of Style.)
    17. Humans can assume, suppose, etc. Mathematical expressions, protocols, etc. can’t.
    18. One multiplies factors together and sums terms. Don’t call factors terms and vice versa.
    19. If you mean “X equals Y,” say so. Don’t write “X agrees with Y,” “X matches Y,” or “we identify X with Y.” The latter three phrases are vaguer, and two of them contain more words, than “X equals Y.”
    20. Regarding the words “general” and “generally”:
      1. A general object subsumes every example of that object. If any example behaves unlike a supposedly general object, don’t call the object general.
      2. Many claims contain the term “general,” “generally,” or “in general” but don’t need the term.
        • Example of a sentence that contains “generally”: The terms generally commute.
        • Equivalent, more concise sentence: The terms commute.
      3. Physicists tend to use the words “general” and “generic” differently. By “general,” physicists usually mean “subsuming every example.” By “generic,” we usually mean “typical,” or “common.”
    21. “Then” makes sense (i) in discussions of chronology and (ii) in if–then statements. Don’t use “then” outside these contexts.
      • Example of inappropriate use: “Define X:=\ldots Then Y.”
      • Examples of appropriate alternatives
        • Define X:=\ldots This definition implies Y.
        • If X:=\ldots \, , then Y.
        • Define X:=\ldots \, , such that Y.
    22. Don’t justify any equation with “we used that [such-and-such is true],” which violates the rules of grammar. Grammatically correct alternatives include “We applied [a property],” “The equation follows from [a property],” and “…since [such-and-such is true].”
    23. Regarding tense:
      1. When describing what you’ve accomplished, use only one tense.
      2. Experiments happened in the past, so describe them in the past tense.
      3. When describing a proof’s steps, use the present tense.
        • Example: We Taylor-approximate the function about x=0. Substituting into Eq. (1) yields [equation].
    24. Nouns, verbs, and adjectives should agree about whether a quantity is singular or plural.
      • Example of singular–plural mismatch: The equations are a rule for evolving the cellular automaton.
      • Example alternative: The equations form a rule for evolving the cellular automaton.
    25. “Admit of” means “allow for,” or “permit.” The phrase needs the “of.”
      • Example: The formula admits of the following interpretation.
    26. Use a pronoun only if the reader can identify its antecedent without ambiguity.
    27. “Spin” has many meanings: “a quantum property that resembles angular momentum,” “a particle endowed with that property,” “the observable \vec{S}^2,” “the spin quantum number s,” “the observable S_z \, ,” “the magnetic spin quantum number m_s \, ,” and “the observable \vec{S}.” Leave no ambiguity about which object you have in mind.
  3. Punctuation
    1. Consider any list that contains at least three items. If no item contains a comma, separate the items with commas. If any item contains a comma, separate the items with semicolons.
    2. In American English, periods and commas belong inside quotation marks. (Example: She told me, “Have a good day.”) In British English, periods and commas belong outside quotation marks. (Example: She told me, “Have a good day”.)
    3. To write quotation marks in LaTeX, don’t use your keyboard’s quotation-mark key; use the appropriate keys.
    4. Regarding hyphens:
      1. The hyphen (-) feeds into punctuation of three types: the hyphen (-), the en dash (–), and the em dash (—).
      2. The hyphen appears in some compound words, as in “non-negative.”
      3. In American English, em dashes can separate ideas within a sentence. Don’t separate any em dash from neighboring text with a space.
        • Example of appropriate use: The sample—the only product of this experiment—barely survived.
        • Example of inappropriate use: The sample — the only product of this experiment — barely survived.
        • Example of appropriate use: He told me only one sample had survived—hardly what I wanted to hear.
      4. This article specifies how to use the en dash. One use is “to separate the names of two or more people used as a compound modifier.”
        • Example: Feynman–Kitaev clock
      5. Hyphenate compound adjectives.
      6. If an adverb ends in “-ly,” it probably shouldn’t precede a hyphen.
        • Example of inappropriate hyphenation: strongly-coupled systems
      7. Follow a prefix with a hyphen if and only if the Physical Review style guide indicates that you should.
    5. A complete clause must follow any semicolon (unless the semicolon separates items in a list).
  4. Math
    1. Introduce only necessary notation, which readers will have enough trouble remembering. If a mathematical symbol appears only once, eliminate it. If a symbol appears only twice, try to eliminate it.
    2. Every sentence must obey the rules of English grammar, punctuation, and syntax, regardless of whether the sentence contains mathematical symbols. All math-containing sentences must end with punctuation marks. If a sentence contains a list of mathematical expressions, precede the final expressions with an “and.” If the list contains at least three mathematical expressions, separate them with commas.
    3. Introduce almost every mathematical symbol before you use it. If you introduce a symbol after using it, the reader will encounter the first use, stop, feel confused for a while, tentatively continue, find the definition, return to the earlier use to understand it, and then progress again. This back-and-forth breaks up the reading process. You may define a mathematical symbol after using it only if (i) the symbol is very common, known to nearly all physicists, and unmistakeable and (ii) defining the symbol earlier would disrupt the text’s flow.
    4. If you define a new function, denote it by only one letter. (I defer in this matter to the Physical Review style guide.)
      • Example: f(x,y,z)
      • Examples of disallowed notation: fxn(x,y,z), {\rm fxn}(x,y,z)
    5. Suppose that a superscript or subscript stands for a word or phrase without representing any variable or constant. The superscript/subscript must not be italicized. (I defer in this matter to Physical Review style guide.)
      • Example: Let x_{\mathrm{meas}} denote the measurement outcome.
    6. If a variable or constant appears in a superscript, parenthesize it. The parentheses communicate that the superscript isn’t an exponent.
      • Example: Let \sigma_z^{(j)} denote the Pauli-z operator of qubit j.
      • If a superscript is not italicized (stands for a word or phrase), don’t parenthesize it.
    7. Regarding the definition of a symbol A:
      1. If you write A alone on one side of a defining equation, use \coloneqq or \eqqcolon: A \coloneqq [expression], or [expression] \eqqcolon A. The symbols \coloneqq and \eqqcolon relate more information than does \equiv, encoding directionality.
      2. Use \equiv if A does not appear alone on its side of the equation: [function of A] \equiv [result of replacing A with its definition in the equation’s left-hand side].
    8. Refer to the Cartesian axes using the formatting “[italicized letter]-axis.” Don’t include any hat, boldface, or \vec symbol.
      • Example: x-axis
    9. Avoid denoting any index by i, which means \sqrt{-1} to physicists. Use j instead, unless you’re writing for engineers (who denote \sqrt{-1} by j).
    10. Don’t use the lowercase letter l (“ell”) as an index; readers might mistake it for a one. Use \ell (\ell) instead.
    11. Give every set-off equation a number. Readers (and coauthors) may want to refer to the equation easily when discussing the paper. Save them (and us) from having to say, e.g., “that equation halfway down page three.”
    12. When writing a set-off mathematical expression, use the align environment, not the equation environment. Using the align environment, one can easily extend an expression across multiple lines.
    13. Regarding a set-off mathematical expression that extends across multiple lines:
      1. Format the expression as follows by default.
        1. Put an & symbol immediately leftward of the first = sign or analogous symbol (e.g., \leq).
        2. If any subsequent line begins with another = sign (or analogous symbol), put an & immediately leftward of the symbol. (I’ll stop writing “or analogous symbol.”)
        3. Suppose that a subsequent line begins with a +, –, \times, or /. Find the symbol immediately rightward of the initial = sign. Begin the new line directly below that symbol.
        • Example:
      2. Modify the default formatting if necessary (a) to reduce the number of lines used in a PRL submission or (b) if the initial = appears awkwardly far to the right.
        • Example of (b):
      3. Suppose a new line begins with a term or factor, such as the jx^8 in the example under (A). Put the corresponding +, –, \times, or / at the beginning of the new line, not at the end of the previous line.
        • Examples of inappropriate placement:
    14. The symbol \approx means “approximately equals”; and ~, “scales as.” Approximations convey more information than scaling relations do.
    15. Use big-O-type notation or ~ symbols, not both; they’re partially redundant.
    16. \ldots, rather than \cdots, should stand in for elements that fit a pattern.
      • Example: x_1,x_2,\ldots,x_n
    17. When using \ldots as in the previous rule, present at least two initial examples of the pattern. One can’t define the pattern.
      • Contains insufficient examples: x_1,\ldots,x_n \, . For example, if n is odd, then x_1, x_2, \ldots, x_n and x_1, x_3, \ldots, x_n fit the template.
    18. Parentheses (), square brackets [], and curly braces {} are delimiters. If you nest them, do so in the order dictated by the Physical Review style guide.
    19. If delimiters enclose a symbol, it shouldn’t protrude above or below them (unless the delimiters would have to be grotesquely enormous). Use the \left and \right commands if the delimiters appear on the same line.
    20. An operator O isn’t a matrix; a matrix represents an operator in terms of a particular basis. Therefore, no equals sign should interrelate an O and a matrix. An arrow can.
      • Example: O\to\begin{bmatrix}1&0\\0&2\end{bmatrix}
    21. Every real number is complex. Don’t say “complex” if you mean “nonreal.”
    22. Consider introducing a mathematical symbol in a prose sentence without using a comma or colon. Put the symbol immediately after the word that names the object represented by the symbol.
      • Example of inappropriate placement: the set of real numbers \{ a, b \}
      • Examples of appropriate placements
        • the set \{a, b\} of real numbers
        • the set of real numbers a and b
        • Recall the set of real numbers, \{a, b\}, in Lemma 1.
  5. More mechanics of writing
    1. Use concise sentences, as advocated for in The Elements of Style. The reader can hold only so many ideas in their head at once.
    2. Structure sentences simply, as advocated for in The Elements of Style. The reader should be able to grasp each sentence easily.
      • Avoid nesting ideas within a sentence, to avoid convoluting the sentence’s structure.
        • Example of sentence with convoluted, nested structure: Any model of equilibrium and nonequilibrium behaviors of systems observed in tabletop experiments and high-energy colliders must obey the laws of relativistic quantum mechanics.
        • Visualization of the nesting: [Any model of ([(equilibrium and nonequilibrium) behaviors] of {systems observed in [(tabletop experiments) and (high-energy colliders)]})] must obey [the laws of (relativistic quantum mechanics)].
    3. The ideal paper title has the structure of a newspaper headline: it presents a claim, containing a subject and a predicate.
    4. Regarding abbreviations:
      1. Don’t abbreviate the first word in any sentence.
      2. Abbreviate “Figure,” “Section,” “Professor,” and “Appendix” if such a word appears partway through a sentence.
      3. Don’t abbreviate “Sections.”
    5. Regarding acronyms:
      1. Write every acronym in capital letters, as per the Physical Review style guide.
      2. Introduce each acronym the first time you use it.
      3. Thereafter, use only the acronym, not the spelled-out phrase, throughout the rest of the document’s main text. You may spell out the phrase in section, figure, and table titles if doing so improves the document’s clarity.
    6. Every paragraph should contain at least three sentences.
    7. Wherever you insert a blank line into your LateX code, a new paragraph begins in the corresponding PDF. Insert a blank line only if you wish to begin a new paragraph. This advice applies immediately before and after set-off equations.
    8. Never begin a subsection immediately after a section title. Between the two titles, overview the section. Analogous rules govern subsections and subsubsections.
    9. Put the word “only” in the appropriate place.
      • For example, suppose you’ve sampled data at a point x=0 in parameter space and sampled data at no other points. “We sampled data only at x=0” is correct; “We only sampled data at x=0” is probably not. The latter claim means that (i) you might have sampled data at x=0 and (ii) you did nothing to the x=0 data apart from sample it: you didn’t analyze the x=0 data, discuss the x=0 data, etc.
    10. Specify subjects and objects precisely. Often, a physicist will describe an idea in several lines. In the following sentence, the physicist will attempt to encapsulate the idea in the word “this.” The pronoun is too vague to specify the idea. This what? Follow the pronoun with a noun.
  6. When in doubt, consult the Physical Review style guide or The Elements of Style.
    • If those references don’t contain the information you seek, search for it in online writing guides. Not all such guides have equal merit, however. Lean toward guides written by human editors or published by college writing centers.

1 Collaborators have wondered why I use green; a student guessed it’s my favorite color. It isn’t; but I bleed green, having graduated from the Big Green, also known as Dartmouth College. Sometimes, I highlight certain pieces of text for one reason (e.g., to point out logical inconsistencies) and other text for another reason (e.g., to point out grammatical inconsistencies). Green distinguishes the first highlightings, while orange distinguishes the second: when not bleeding Dartmouth green, I bleed Caltech orange.

2 Don’t learn how to write from physics papers. 

Matt von Hippel — The Weird Incentives of Word Count

Many freelancers get paid per hour, or per day. Some have standard rates for typical tasks.

Journalism is rarely typical. And usually, we’re paid per word.

I’ve had many friends whose first thought is how easy that must be to exploit. Often they remember a story about a writer like Charles Dickens or Victor Hugo padding their books with digressions to up their pay. Those stories probably didn’t happen, and these days, that method is even less likely to work. When I pitch a piece, the editor and I agree beforehand on a target word count. The only way I get paid more than expected is if the editor agrees that it makes sense.

That said, there definitely are ways to exploit being paid by the word, if you wanted to. They’re just more subtle.

The source of any such exploit is to notice that writing is not actually the hard part of journalism. Research is time-consuming: the more people you talk to, the longer it takes. Writing, once you’re used to it, can go quite quickly. So the length of a piece itself doesn’t determine how much work it takes to write: research does.

In principle, longer pieces are supposed to take more research. Editors will have rough expectations for the number of sources you’ll interview, so this isn’t something you can skimp on, per se. And publications known for their high standards for research usually pay larger rates per-word.

But no matter how much you’re paid, research can go out of hand in the other direction. Journalism is about finding out the truth, and sometimes the truth is more complicated than expected. Sometimes you need more information, and need to fit in one more interview, then another, or run around chasing after missing info. Then you need to figure out how to fit it all into the same word count you started with.

So suppose you’re a freelancer who aspires to consistently pay their bills. You want to earn a certain amount per hour worked, but some projects can take much more work than others. So what do you do?

You look for the simple. You try to find stories that are unlikely to be complicated, that won’t have clashes of opinion that need to be represented or experts with different sides of the story. If you don’t find such a story, you simplify: you write a piece that makes the story sound cohesive, that papers over doubt, even if you’ve run into doubts yourself while writing it. If you’re consistent about it, you can do what your friends with salaries do, and earn a stable living.

Not the kind of exploit you had in mind, I suspect. And not, despite the sound of it, something you can do reliably. I find I’m always tempted by complexity, always drawn to investigate a story that’s a bit too big for the wordcount it’s supposed to fit.

But it is an ever-present incentive, one I suspect people with a larger roster of leads start to feel. If you’re paid by the word, then the best story tends to be a tidy one.

Terence Tao — IAS applications for membership in the school of mathematics

The IAS has opened its application page for its membership program for the upcoming year. This by itself would be unremarkable — the program does this every year — but there is an additional statement included in the announcement:

We realize that applying to positions in the current environment is stressful. To help alleviate this, the School of Mathematics offers applicants the option to submit research statement based only on already conducted research. It would be helpful if such a statement would be focused on a few select projects (in most cases up to three) and not a wide ranging list.

I would expect other departments and institutes advertising positions this year to adopt similar guidance. (See also a recent report from a working group making similar recommendations in the area of theoretical computer science.)

Readers are also invited to post links to other job openings in mathematics in the comments.

Proofs and Prompts — A Response to “Who will become the new mathematicians of Math 2.0?”

Álvaro Lozano-Robledo, Professor of Mathematics at the University of Connecticut and on Youtube

In reply to Who will become the new mathematicians of Math 2.0? by Anonymous

SERIES · As application deadlines approach, Proofs and Prompts is publishing a series of posts from 19 to 23 October for people considering a PhD, doing a PhD or looking for a postdoc: guidelines, discussions and speculation about what to do and what careers in mathematics will look like. This post is one of them. Each is written independently and reflects only its authors’ views. All posts in the series

This is a response to a recent post on Proofs and Prompts titled “Who will become the new mathematicians of Math 2.0?” written by an Anonymous PhD student (who I will refer to as “Anonymous” below). I would urge particularly all tenured and tenure-track mathematicians to read it because there are many students that think the same way, and are planning to leave academia as a consequence.

I recently wrote a guest piece on Terry Tao’s blog (“What should we tell our students?”) where I warned that we are ‘about to lose an entire generation of mathematicians’ so I feel a duty to reply to Anonymous’ post, to try to offer some counterpoints to the arguments expressed therein. More importantly, I feel a duty to talk to my students about these issues, and I have shared Anonymous’ post with them, so that we can have a discussion. I hope my colleagues in the mathematical community reach out to their students as well.

In order to respond to Anonymous, I will quote some key sentences, and then elaborate with my own thoughts.

I recently heard a mathematician say that it is “paradoxical” to not want to study a field that is undergoing a scientific revolution in reference to October 6th. This mindset completely misses the point of why I do mathematics, and I suspect this is true for many other graduate students and even other established mathematicians.

I want to start here because I believe I may be one of the mathematicians that they are referring to. In a video discussing my post on Tao’s blog, I said

“And I think it would be in fact paradoxical that people would not want to join a field of study during a scientific revolution where we’re seeing this incredible acceleration.”

I will come back to the ‘paradoxical’ remark later on, but I want to first mention what I said right after that quote:

“It is somewhat chaotic. It seems somewhat confusing to be a mathematician right now. But we are trying to figure out together what should the math landscape look like in a year and in five years and how to navigate… how we can use LLMs in ethical ways and in a way that is going to construct solid mathematics along the way and in a way that the mathematical field is going to thrive.”

Let me elaborate on that. Historic upheavals of the status quo are usually chaotic while they happen, and in many cases many of those living through such times have been trampled and mistreated (with such dramatic and relevant examples as the industrial revolution). It is the duty of those in positions of power or security to fight for the rights and well-being of those who may be more likely to suffer through a revolution. In our case, we are living through what can be considered a technological revolution that has great potential to accelerate research and progress and, at the same time, it has a terrifying civilization-ending non-zero potential. Unfortunately, trying to pretend that the revolution is not happening, or trying to preserve the status quo, only delays the inevitable, and prevents communities from fully preparing and reinforcing their core values, so that their professions can survive said revolution.

If we limit our conversation to mathematics and the mathematical community, the LLMs have already revolutionized research mathematics, with the proposed resolution of several landmark conjectures, such as Navier-Stokes or the quasi Riemann hypothesis. This is undeniable and, simply put, we must learn how to coexist with this new technology. But they are also an existential threat to the way mathematics works, and the way the mathematical community operates. So it is absolutely normal and expected to be excited about the research advances, and also extremely concerned about the ways it may change our field, as Anonymous very eloquently points out.

In particular, while the OAI drop of October 6th is certainly of “historic” proportions, it clearly also has had a disruptive effect of historic proportions. Whether the global effect of the LLMs will be a net positive will be determined much later in the future. But it is clear that the “arms race” of frontier model companies to develop ever more capable mathematical models is a corporate publicity stunt and, very early on, even before the Fields medalists warned of a misalignment in an open letter, I asked mathematicians not to be complicit in such an arms race.

At the end of my video about the Oct 6 drop, I encouraged people to stay in the field to make changes from within the community. It is up to us in the profession, and more so up to the newer generations, to lead the way to ethical and sustainable research practices that will allow mathematics to prosper. How to do so is to be decided, so all of Anonymous points are well taken. Whatever we do, we need to make sure students do not abandon mathematics because they think it has become unrecognizable. But the key question is: who is in charge of making these changes and laying out a path forward? I claim that no one is in charge, and we all are. Precisely those that see the field driving towards a cliff, have a great role to play within the community to warn about such dangers! It is a chaotic time, the future is uncertain, and this is disconcerting, but I think there are many reasons to be optimistic and to continue in the mathematical profession.

Now let me backtrack in Anonymous’ post to the very first line:

To the mathematicians shaping the future of our profession,

The mathematical community is not monolithic, and this is a feature, not a bug, of the community. There is no single person, group, or entity that dictates what mathematicians do or how they should operate. In particular, Terry Tao is not a spokesperson for all of mathematics and, of course, there are many out there that do not agree with his views and his predictions for the future of mathematics. Personally, I highly value and respect many of the things he has said, and I disagree with others. I single out Tao here because Anonymous does, but we could similarly agree or disagree on Tsimerman’s or Duminil-Copin’s points… or any other non-Fields medalist point of view, from one of the many recent blog posts on the matter of AI.

Right now, there are many different groups trying to pull mathematics in very different directions. For example, while some mathematicians are completely embracing LLMs, other mathematicians completely refuse to use LLMs in their work. Some of us are choosing the middle ground, and we use LLMs with caution for certain tasks, we avoid them for other more intellectual tasks, while respecting the decisions of some of our colleagues (I include students in this category) who cherish them, or do not wish to use them at all.

When students choose graduate programs, and PhD advisors, many of us encourage them to ask lots of questions (to the staff, to faculty members, to students, to friends) about the atmosphere in the department, and their practices, and about the personalities of the potential advisors. Similarly, I would encourage students who are thinking of a career in mathematics to reach out to their current or prospective programs and advisors, and enquire about their stance on AI/LLM use. Does it match the student’s own attitude towards AI, or is it antithetical to their ideals? Since the community is far from monolithic, there are plenty of departments and potential advisors that will be aligned with whatever views the student holds, and it would be wise to choose programs based on that type of alignment, if the issue of AI is key in the decision making.

I love technical work. I love spending days, weeks, months working on a lemma or an idea without success. […] As AI has now become highly capable of performing this kind of work, I see shockingly little from the mathematics community about how this kind of crisis in education will be addressed.

There was a recent summit on “PhD Math Education in the Age of AI” and the recommendations for graduate programs can be found here. TPSE is putting together a panel discussion on the Future of Graduate Education in Mathematics. Many departments are having internal discussions on how to approach these issues. As I said above, the future is uncertain but we are trying to think of the best possibilities in education as well as in research.

What is the goal of a graduate program in mathematics? How do we define success in a PhD program? In my opinion, the PhD is an apprenticeship, and success is measured by whether the candidate has been trained and is proficient in all aspects of the mathematical profession. At the end of their degree, several mathematicians write letters of recommendation. A (good) rec letter or set of letters evaluates the PhD candidate’s aptitude in all of these aspects: research potential, teaching abilities, service to the community, potential as a colleague, etc. And then colleagues in other institutions read these letters and determine whether the candidate will be a good match for the research and/or teaching needs of their department. Many of the conversations surrounding AI concentrate on the research aspects, but there is a lot more to being a mathematician than just research.

On the subject of research aptitude, will letters in the future refer to the fantastic LLM skills of the candidate? Will we compare students and say such and such student is in the top 2% of LLM-prompters that we have ever met? Will we say wonderful things about their slop-paper output in our letters? Will we praise the many slop-papers that they have been able to de-slopify? I do not think so – we will still need to have a way to measure their research potential based on their own capability of thinking deeply about problems, and coming up with innovative ways to attack interesting problems. It is absolutely true, as Anonymous points out, that students need to spend long hours thinking deeply about a problem, and I do not think LLMs should change that. So PhD advisors should encourage students not to use LLMs for certain tasks such as proof generation of key lemmas, because these are the tasks where intellectual development actually happens (see the Specific Recommendations in the section on Research and AI in the recommendations from the Summit). In a recent conference I was at, someone suggested to grad students to always be working on at least one project that is completely LLM-free.

As a result, I do not think anyone should or will rob the students from their long hours working on a lemma by “pure thought” because most of us recognize the irreplaceable value of the time spent on that activity. It is precisely the outcome of those thinking sessions that sets students apart at the time of evaluating their intellectual and research ability in research letters.

On the other hand, if an advisor demands results with a quick turnaround, and expects that the student will access an LLM for help to be able to move on – against the wishes of the student – then it is time to choose a different advisor. The ideal scenario is that the student will ask the advisor for help or a hint on how to proceed, even if an LLM could provide such ideas, because those conversations are actually also part of the apprenticeship: students learn how to collaborate with other mathematicians through those interactions. Plus the advisor may have a much better intuition than the LLM does anyway.

Many celebrate the possibility that AI will relieve them of the burden of difficult calculations, technical lemmas, and other supposedly tedious aspects of mathematical research.

I do not think that is a common sentiment. For the most part, we all value the time spent in understanding the technical difficulties of key lemmas. On the other hand, LLMs can be fantastic tools in helping us write code and run numerical experiments. I am not great at coding, and I find that the LLMs are allowing me to run computations that I only dreamed possible. It would have been very tedious for me to learn how to write code in Python, html, javascript, etc., but now I am able to create code in all those languages, run experiments, and later verify the results mathematically, all in hours instead of weeks (or instead of never!).

Terence Tao has proposed a vision of a new way of doing mathematics, Math 2.0, where the emphasis moves away from solving open problems and toward a more holistic approach. […] But I feel like I am asking the obvious question that has not been addressed: What if I do not want to spend my professional life doing these activities?

Two points here. One (1), some of us have always had a holistic approach to a PhD: I have always emphasized to my students that I expect them to become well-rounded mathematicians, not just great researchers, and that means that I try to push them not just to write a great thesis, but to be better instructors, better members of the community, better at networking, better colleagues, better at giving talks at all levels, etc. There is nothing wrong with a holistic approach, and in fact it makes candidates more appealing to a broader range of colleges and universities at the time of applying for jobs.

And two (2), many do not agree with Tao’s vision either, and that is ok. In my research, I want to solve problems. The coolest the problem the better. I do want to think about a problem and come up with an ingenious solution, and then tell the world about it. I do not want to inherit a slop-solution to a problem that a company dropped in a repository, and try to make sense of it. I would not want to do that, and I would not expect a student to want to do that either, so I would not ask a student to do that as part of their duties to complete a PhD. I simply do not think we will move in the direction of “moving away from solving problems.”

However, I have thought of problems that an LLM could solve, prompted them, and now I have LLM-prepared drafts on problems I care about. Instead of posting these papers directly to Hexagonmath.org, say, my current strategy is to introduce students to research by explaining the problem I am interested in, explaining why others are also interested in the same problem, discussing the idea that led me to prompt an LLM, and sharing the paper with the student. Then use that paper and that topic as a thread for an independent study on the particular area, so that the student learns enough background to understand the motivation for the paper, and the techniques that are used to solve the problem. Later, we will read together the LLM draft, understand the proof, and rewrite it in a way we understand and can make sense of it. While we think about the proofs, I hope we come up with ways to extend the arguments to strengthen the result, or apply the techniques to other similar problems. And finally polish the paper so that we can submit it to a journal, so that the student has an early experience in writing a research paper, and so that they have published a paper early on to talk about during research conferences. A paper they understand and they can feel is their own, because they have contributed to make it their own.

Will this strategy work? I do not know! I am just trying things out, honestly, and I am listening to any other mathematicians who are trying out different strategies to coexist with the new technology.

I do not expect to follow this early-LLM-draft protocol for a thesis problem, however. It would only be appropriate just as some first steps into research.

There is a problem with the proposed future of mathematics, and it is more concerning than my personal dissatisfaction. How exactly do you expect to train the next generation of mathematicians? You know how to formulate new research directions. Where did these skills come from? I doubt they were developed by reading successful proofs or listening to an explanation of an idea.

As a matter of fact, I do not think intuition and mathematical taste is learned by thinking deeply about a problem for hours on end. I have learned much more attending lectures and conferences, and talking to other mathematicians during lunches and dinners. I have had my best ideas reading other people’s papers and proofs. As an anecdote, early on in my career I signed up to write brief reviews for MathSciNet. I am not sure exactly why, but I was assigned to read and review several articles by Bo-Hae Im (some solo papers, and some co-authored by Im and others), and after reading the third or fourth paper by Im dealing with a conjecture of Larsen, I had an idea of how to prove a related result. I wrote to Im and we ended up collaborating on a research article that eventually was published by the Journal of the London Mathematical Society (and it had a significant impact in getting tenure).

As I mentioned above, we should make an explicit effort to allow students to think deeply about problems, but we should also make it clear that students should be reading papers and proofs. And whether we like it or not, some of the proofs dropped by OAI contain some interesting arguments that we should absolutely study and think about! A particularly valuable example is the proof of the non-existence of Siegel zeros, which several mathematicians (Banks, Kerr, Green, Barreto) have improved on, and now it seems the papers have converged to a remarkably simple argument that many of us would highly benefit from understanding.

Back to the question on how to train the next generation of mathematicians… I am not sure we have the answers yet, but I do not think it will look dramatically different from what we do now. There is a new tool in town, yes, but the guiding principles should be the same: train students to be well-rounded mathematicians.

If the future consists of interpreting AI generated results, organizing knowledge, and directing automated research, why should I remain in academia?

The way this question is phrased, it assumes that the worst, most dystopian possible scenario will come to pass, where AI can solve any single problem humans could solve, and that we would reach a point where only machines do math research. As I mentioned in my piece in Tao’s blog, the future of LLM capabilities is completely unclear. There are many ways in which LLMs could hit a limit in mathematics, for example from the theoretical or feasibility points of view. The frontier model companies are driving the narrative and trying to convince us all that their products are already super human when this is far from the truth. I wish mathematicians had a multi-million PR team behind them to build praise and support for our fantastic research record!

The reality is that many of us have started using LLMs to aid our research, as a tool or as a collaborator, and it turns out that it can be very exciting and fulfilling to do so. As one of the best recent examples of LLM use I know of, one of my colleagues (Kyu-Hwan Lee) joined a team of mathematicians to prove that the sporadic simple group M_23 is Galois over Q. Their team succeeded with the help of LLMs in a task that many had tried and failed, and made some really interesting progress in the inverse Galois problem. Here is an excerpt from their declaration of AI use:

“No text in this article was written by AI. Our work relies on longstanding domain knowledge and techniques for computing curves of positive genus [KMSV14]. The key strategic decisions and the conceptual analysis for this project were made by the human team.

AI served as a tool that accelerated a large part of our work, particularly the computations. We used Claude Fable 5 and 5.1, Claude Opus 4.8, and ChatGPT 5.6 Sol for searching the literature, generating code, checking results, and proofreading. The workflow that eventually succeeded was a tightly controlled collaboration in which the computational work was much faster with AI, while the human collaborators continued to direct the research and verify the results. AI systems increased our confidence in tackling difficult problems and helped us communicate more efficiently across our different areas of expertise.”

I find this result fantastic (the paper is a gem by the way), and I think it exactly illustrates the way senior mathematicians (Lee, Poonen, Pries) can use LLMs to accelerate research and understanding, and include graduate students (Shaowu Zhang) and postdocs (Xiaoyu Huang) in the process!

Mathematics is never going to be the same and I recognize that the way I did research and found fulfillment from it are no longer here.

Mathematics will be different, yes, but I firmly believe it will be similar to what we do now, in all the best ways. As a final example, very recently three mathematicians (Elkies, Klagsbrun, and Li) have found an elliptic curve of rank 32. I find this discovery astonishing and wildly exciting. In a private communication, Zev Klagsbrun mentioned to me

“It would be a mistake to view this as a triumph of humans over AI. In fact, it’s a great example of humans using AI to push the boundary of what is known.”

I could not agree more. Immediately after their curve was found, my student Dylan Costa and I started working on finding a quadratic twist of their curve with rank bigger or equal to 3 (in order to find a quadratic field over which their curve achieves rank at least 35), and with the help of LLMs (in coding and literature search) we succeeded to find one, conditional to BSD/Parity. Both Dylan and I found the work on this little contribution (certainly little compared to the giant discovery of the rank 32 curve) to be exhilarating. It would not have been possible just a few months ago without the help of LLMs. This is why I would find it paradoxical to leave mathematics now.

I am not asking you to agree with my personal preferences.

I just want to conclude by thanking Anonymous for writing such a great piece that should make everyone in math think long and hard about the future of the profession. Thank you. And a final message just to Anonymous: I would love to record an interview with you and post it in my channel. Or send me an email message if you want to chat. Bye and best of luck!


Received 22 October 2026.

Proofs and Prompts — Disgusted by AI?

Marcus Zibrowius, Professor at Heinrich Heine University Düsseldorf

AI models are making mathematical progress at an unimaginable scale. There’s now a reasonable expectation that soon, we will be able to prove a theorem, or find a counterexample, at the touch of a button.

But the overall reaction of our mathematical community is closer to panic than it is to enthusiasm. AI is perceived as a threat, not just to humanity as a whole (which is a different story) but to mathematics specifically. We are collectively appalled by formally-verified but fully inexplicable proofs, and even more disgusted by companies that churn out one AI-generated (and equally verified) paper after the other without even having a single person on the team able to explain them.

We talk about the good old days when mathematics was about building a community of common understanding, facilitating personal growth, celebrating beauty.

What a feel-good fairy-tale that is!

In fact, our values have always been about who got there first. Collectively speaking, the one thing we, as a mathematical community, have always valued most has been a proof of a hitherto unproven theorem. It was not a nicer proof of a known result, and certainly not a beautiful exposition of a known proof.

You think I’m being cynical? Allow me to argue my point.

Follow the money.

Explaining a proof may have earned you an applause or a compliment. Completing a proof –\text{\textendash} and doing so faster than anyone else –\text{\textendash} is what has always had the potential of getting you a job. Also, when did you last write a grant proposal promising to deepen the communal understanding of an existing proof, or to find a more digestible proof to a proven theorem? How does the amount of funding you have acquired for promising new results compare to the funding you got for explaining existing ones?

Reflect on common behaviour.

What is more likely to keep you up at night? A fellow mathematician threatening to arrive at “your” result ahead of you, or a fellow mathematician having trouble understanding your arguments?

The other day, an eminent mathematician confessed to me over lunch that they worked through their summer holidays to get out a paper with a new construction that they got out of an AI model. Anyone asking the model the same question would get the same ingenious answer, so the logic went, hence they needed to publish this immediately.

On the flip side, I’ve sat through talks where the speaker afterwards, privately, declared “Today I have given a talk that was utterly incomprehensible. I’ve always wanted to give a talk like this.” To be fair, this was a singular, extreme case. But we would not tolerate this kind of behaviour if we really cared so much about a community of common understanding.

Acknowledge past grievances.

Personally, I vividly remember how, at a panel discussion on “Future Directions of Algebraic Topology” at Stanford in 2012, one of the younger members of the audience raised the question: What can we do to make mathematical culture more like music culture, where presenters are valued as much as composers? At that time, the idea of AI was still very much hypothetical. The question was about our very own, human culture.

Read the Leiden declaration.

The Leiden declaration, which has been widely endorsed by the mathematical community, lists the following as one of our five mathematical “values”:

Results are attributable to specific authors who take credit for their discovery and assume responsibility for their correctness. These principles ground the merit-based standards to which we aspire in mathematical research.

That is just another way of saying that the one thing that really matters for your standing within the community is that you arrive at a new result first.

So why am I saying this? Because I completely disagree with the notion that AI companies have hijacked our mathematical culture and turned it into something new and unrecognizable. They have not. Quite the opposite. They are playing to our rules. They are even solving our problems, problems that no one else cares about! They have just taken our existing culture to its extreme.

And now, we are disgusted!?

I would argue that what we’re really disgusted by is a key aspect of our own culture, now that we see it more clearly than ever before. We’re disgusted by the idea that getting there first is all that matters.

Let’s be honest about what was and what is. We defined our priorities. AI serves them better than we can. Perhaps, the priorities were off.


Received 25 September 2026.

Proofs and Prompts — Towards a world mathematical commons

Kunal Marwaha, Ph.D student at University of Chicago

SERIES · As application deadlines approach, Proofs and Prompts is publishing a series of posts from 19 to 23 October for people considering a PhD, doing a PhD or looking for a postdoc: guidelines, discussions and speculation about what to do and what careers in mathematics will look like. This post is one of them. Each is written independently and reflects only its authors’ views. All posts in the series

Mathematics is a creative and emotional endeavor. We are driven by challenge and curiosity. We express our ideas carefully to be precisely understood. Our highest moments can fill us with exhilaration and awe.

But how we do mathematics has evolved over time. We have moved away from pictures and informal arguments; we now have axioms and proofs. We have outgrown the time when one person could have understood all of known mathematics; now, we specialize, relying on others to teach us what we know less about.

Today, it is clear that mathematics is again changing and growing beyond us. There exist machines which can prove new mathematical statements, and convert them into papers for humans to verify. This is strange and disruptive to our current process. However, I offer a positive vision of a future which includes these machines while preserving our motivations for this extreme passion.

We should change our mindset from explorers of the mathematical frontier to stewards of a world commons of mathematics.

A commons is a societal resource available to all because it improves everyone’s quality of life. My favorite example is the US National Park system. At a national park, I can reliably experience an overwhelm of natural beauty in mountains, forests, or rivers. I can camp, swim, or just walk on a trail. After a weekend trip, I return to my normal life refreshed and inspired.

I like the outdoors, but I am not very adventurous. For some people I know, the outdoors can feel like home. They will go into nature for weeks or months at a time: backpacking, rock climbing, journaling. One can make a living like this as a park ranger or firefighter; people in these jobs are paid to understand wildlife, take responsibility for keeping man and nature in balance, and build trails to make life pleasant for visitors like me.

We can build the same kind of environment for mathematics.

For many of us, research is more of a passion than a job. The mathematical outdoors feels like home. This is why theorem-proving machines can feel so intimidating: they are strange new creatures. I think the machines are here to stay, and I don’t think we can control which problems they will solve. Instead, we should learn from them, keep them in balance with human understanding, and show other humans the beauty of this place. We can be the rangers and firefighters of our mathematical parks, which are more alive than ever before.

The sudden advent of theorem-proving machines will make the next few years painful and difficult. However, if we do not act, we may quickly lose relevance, and our community is likely to wither. This makes building a mathematical commons extremely urgent. But what would it take to build this commons?

The most important step is to create a coalition of mathematicians to steward the commons. We should create a non-profit with a large advisory board, who represent the broad and diverse interests of people who prove or teach theorems in their work. This organization should not be run by any AI company, and our artifacts should be open to everyone.

The next step is to convert all mathematics into formally verified statements. This is the goal of the Mathematics Autoformalization Project. If we can use computer code to certify correctness of a proof, we can maintain our trust in these proofs at scale. Today, the most popular way to formally verify mathematics uses the Lean proof assistant. There is a vibrant open-source community around Mathlib, which has verified essentially all of undergraduate mathematics. It is now even possible to use LLMs to convert proofs of research-grade theorems directly into Lean. (The recent formalization of Fermat’s Last Theorem used the public prove2.me site I helped build.)

Formalizing all of mathematics would create a large directed graph of known statements and their implications. Creating this graph is achievable if AI companies donate some compute resources to the mathematical commons. Here, they can work together instead of against each other. In the future, all new results could be added to this graph of knowledge.

The final step is to tame this graph of formally verified statements. We do not have to digest all at once; we only have to manage it. We should cluster and sparsify the graph until it corresponds to human-sized chunks of knowledge. We can look for simplifications, common definitions, and unifying theories. We can build trails through wonderful proofs to share both with other mathematicians and with “park visitors”. This can all be assisted by machines, provided it helps accomplish our goals.

If done well, the commons will bring about a golden age for human understanding. With responsible stewardship, we can nurture the next generation of mathematicians and math appreciators alongside theorem-proving machines.

Let us start by building this broad coalition of mathematicians. If we work together, we can steer the way mathematics evolves in this uncertain future.

Kunal Marwaha


Received 5 October 2026, revised 23 October 2026.

John Baez — The Quasi-Riemann Hypothesis

As part of their big theorem dump, an AI company recently emitted a proof of the ‘quasi-Riemann hypothesis’. Maksym Radziwiłł of New York University said the implications of this result are “staggering”, continuing:

“In a sense, the vast majority of consequences of RH already follow from quasi-RH.”

But what is the quasi-Riemann hypothesis, and what are some of these consequences?

Since 1897, we’ve known all the nontrivial zeros of the Riemann zeta function lie in this strip in the complex plane:

0 < Re(z) < 1

The quasi-Riemann hypothesis says they lie in some narrower strip

a ≤ Re(z) ≤ 1 – a

The Riemann hypothesis claims all these zeros lie exactly on the line

Re(z) = 1/2

The closer to this line we can show these zeros are, the more regular the distribution of primes must be!

First, remember the number of primes less than n is asymptotically n / (ln n). But a more precise estimate of the number of primes less than n is a function called li(n), which is the integral of 1/ln(x) from 0 to n.

The difference between li(n) and n / (ln n) is about n / (ln n)2. This is a lot bigger than the errors I’m going to talk about.

The above graph makes it look like li(n) is always bigger than π(n), but in fact π(n) – li(n) switches sign infinitely often—the first time before 1.4 · 10316.

Before the proof of the quasi-Riemann hypothesis, we knew things like this: if π(n) is the number of primes less than n, then

|π(n) – li(n)| ≤ n / (ln n)1000

if n is large enough. Indeed, we could replace the number 1000 by any other large number.

The Riemann hypothesis is equivalent to this: if π(n) is the number of primes less than n, then

|π(n) – li(n)| ≤ C np

for any p > 1/2, and some C that depends on p. We know we can’t get p all the way down to 1/2.

So crudely, the Riemann hypothesis brings the error bound down from “a lot less than n, but still bigger than any smaller power of n” to “not much more than √n”.

The quasi-Riemann hypothesis does the same thing but replacing √n with some bigger power of n, namely n1-a if all the nontrivial zeros of the Riemann zeta function lie in the strip

a ≤ Re(z) ≤ 1 – a

In the recent massive drop of AI-generated results there’s a long, complicated proof that the quasi-Riemann hypothesis holds for a = 1/8:

• The quasi-Riemann hypothesis, 199 pages.

If this proof turns out to be correct, then we’ll know

|π(n) – li(n)| ≤ C np

for any p > 7/8.

But there’s also a much simpler proof that a = 1/12 works:

• The quasi-Riemann hypothesis, alternate proof, 49 pages.

A bunch of mathematicians have been writing about this, developing similar results—so we can feel pretty sure this is true. Thus, at this point, number theorists are confident that

|π(n) – li(n)| ≤ C np

for any p > 11/12.

But the quasi-Riemann hypothesis has other consequences, too—especially combined with the recent proof that a bunch of L-functions have no ‘Siegel zeros’. One of the cuter, less technical results is called ‘Goldbach conjecture on average’.

You can count, for each even number up to n, the number of ways to write it as a sum of two primes, and add these counts up. The total is close to a simple formula, and the question is how close. The quasi-Riemann hypothesis puts a bound on the error, thus proving Goldbach’s conjecture on average. I’ll spare you the details. Unfortunately, this bound is not good enough to prove Goldbach’s actual conjecture.

There are also plenty of more technical yet more profound implications of the new work on the quasi-Riemann hypothesis. These rely on not just the statement, but the proof method. There are various other important functions in number theory—zeta functions and L-functions—that we can now prove have zeros in a half-plane Re(z) > 1 – a for some fixed a > 0. Write QRH(a) for this statement, so OpenAI’s 7/8 result is QRH(1/8) for the Riemann zeta function.

A recent paper by Frei, Sofos and Widmer summarizes some of what’s been done so far:

• Christopher Frei, Efthymios Sofos and Martin Widmer, Some applications of the quasi-Riemann hypothesis to class groups and small generators of number fields.

For example, one paper in the theorem dump claims QRH(1/8) for all Dirichlet L-functions and all finite-order Hecke L-functions of ℚ√(−3), with a second preprint giving QRH(1/12). Another claims QRH(10-6) for all finite-order Hecke L-functions of cyclotomic fields containing the 12th roots of unity. Most exciting to me, a preprint by Cureton and Thorner claims QRH(1/32) for the Dedekind zeta functions of all number fields:

• Dean Cureton and Jesse Thorner, A quasi-Riemann hypothesis for Dedekind zeta functions.

You may not consider any of these implications “staggering”. But that probably means you’re not an analytic number theorist. According to Joshua Zelinsky, there are hundreds of papers deriving results that can be improved using the quasi-Riemann hypothesis. Mathematicians have been working for over a century to make these things happen.

n-Category Café The Quasi-Riemann Hypothesis

As part of their big theorem dump, an AI company recently emitted a proof of the ‘quasi-Riemann hypothesis’. Maksym Radziwiłł of New York University said the implications of this result are “staggering”, continuing:

“In a sense, the vast majority of consequences of RH already follow from quasi-RH.”

But what is the quasi-Riemann hypothesis, and what are some of these consequences?

Since 1897, we’ve known all the nontrivial zeros of the Riemann zeta function lie in this strip in the complex plane:

0 < Re(z) < 1

The quasi-Riemann hypothesis says they lie in some narrower strip

a ≤ Re(z) ≤ 1 - a

The Riemann hypothesis claims all these zeros lie exactly on the line

Re(z) = 1/2

The closer to this line we can show these zeros are, the more regular the distribution of primes must be!

First, remember the number of primes less than n is asymptotically n / (ln n). But a more precise estimate of the number of primes less than n is a function called li(n), which is the integral of 1/ln(x) from 0 to n.

The difference between li(n) and n / (ln n) is about n / (ln n)2. This is a lot bigger than the errors I’m going to talk about.

Before the proof of the quasi-Riemann hypothesis, we knew things like this: if π(n) is the number of primes less than n, then

|π(n) - li(n)| ≤ n / (ln n)1000

if n is large enough. Indeed, we could replace the number 1000 by any other large number.

The Riemann hypothesis is equivalent to this: if π(n) is the number of primes less than n, then

|π(n) - li(n)| ≤ C np

for any p > 1/2, and some C that depends on p. We know we can’t get p all the way down to 1/2.

So crudely, the Riemann hypothesis brings the error bound down from “a lot less than n, but still bigger than any smaller power of n” to “not much more than √n”.

The quasi-Riemann hypothesis does the same thing but replacing √n with some bigger power of n, namely n1-a, if all the nontrivial zeros of the Riemann zeta function lie in the strip

a ≤ Re(z) ≤ 1 - a

In the recent massive drop of AI-generated results there’s a long, complicated proof that the quasi-Riemann hypothesis holds for a = 1/8:

If this proof turns out to be correct, then we’ll know

|π(n) - li(n)| ≤ C np

for any p > 7/8.

But there’s also a much simpler proof that a = 1/12 works:

A bunch of mathematicians have been writing about this, developing similar results—so we can feel pretty sure this is true. Thus, at this point, number theorists are confident that

|π(n) - li(n)| ≤ C np

for any p > 11/12.

But the quasi-Riemann hypothesis has other consequences, too—especially combined with the recent proof that a bunch of L-functions have no ‘Siegel zeros’. One of the cuter, less technical results is called ‘Goldbach conjecture on average’.

You can count, for each even number up to n, the number of ways to write it as a sum of two primes, and add these counts up. The total is close to a simple formula, and the question is how close. The quasi-Riemann hypothesis puts a bound on the error, thus proving Goldbach’s conjecture on average. I’ll spare you the details. Unfortunately, this bound is not good enough to prove Goldbach’s actual conjecture.

There are also plenty of more technical yet more profound implications of the new work on the quasi-Riemann hypothesis. These rely on not just the statement, but the proof method. There are various other important functions in number theory—zeta functions and L-functions—that we can now prove have zeros in a half-plane Re(z) > 1 - a for some fixed a > 0. Write QRH(a) for this statement, so OpenAI’s 7/8 result is QRH(1/8) for the Riemann zeta function.

A recent paper by Frei, Sofos and Widmer summarizes some of what’s been done so far:

For example, one paper in the theorem dump claims QRH(1/8) for all Dirichlet L-functions and all finite-order Hecke L-functions of ℚ√(−3), with a second preprint giving QRH(1/12). Another claims QRH(10-6) for all finite-order Hecke L-functions of cyclotomic fields containing the 12th roots of unity. Most exciting to me, a preprint by Cureton and Thorner claims QRH(1/32) for the Dedekind zeta functions of all number fields:

You may not consider any of these implications “staggering”. But that probably means you’re not an analytic number theorist. According to Joshua Zelinsky, there are hundreds of papers deriving results that can be improved using the quasi-Riemann hypothesis. Mathematicians have been working for over a century to make these things happen.

October 22, 2026

Scott Aaronson Vote!

Today, I take a break from your regularly-scheduled AI mathocalypse programming to urge my American readers to vote in the Congressional midterms, early if possible, if you haven’t already. Especially if your state faces one or more major contests, as does my adopted home state of Texas.

Me, I voted straight-ticket Democrat today, as I’ve done in every election since I became eligible over a quarter-century ago (except for when I vote-swapped with someone from another state).

So yes, I voted for the guy who studied theology a short walk from my house, and who seems to have really internalized the whole Jesus thing about kindness to everyone—

—over his sneering, thuggish, cartoonishly mafia-like opponent. Fingers crossed that Talarico pulls off a historic upset for our state (he’s currently a 2-to-1 favorite in the prediction markets).

The Texas Republicans did everything they possibly could to make this choice easy for me, by being corrupt, conspiratorial, racist, and Taliban-like even by the jaw-droppingly debased standards of MAGA in 2026. As I draw breath, I could never vote for a slate one of whose candidates attacked UT students for the crime of being visibly Southeast Asian while cheering their school’s football victory from the stands—and whose other candidates could barely bring themselves to condemn this knuckle-dragging racist, for fear of angering their base. (It’s like, didn’t you want immigrants to assimilate to American culture? What more could these kids possibly do, short of skin bleach?)

All the same, this was also the first US election in my lifetime where I felt like my vote was genuinely in play—especially when I listened to Talarico’s condemnations of Israel, for having the temerity to fight the same kind of war any random other nation would’ve fought had it been attacked as Israel was on October 7. When Hasan Piker came to speak to a cheering crowd here at UT Austin, I actually wrote to someone I know in the Talarico campaign, to ask whether Talarico would show enough balls to condemn Piker’s many antisemitic and anti-American statements, and renounce his support. My contact was nice enough to reply to me, saying: don’t worry, James is taking care to be far away from Austin during Piker’s visit, so he won’t need to engage at all!

So then, this is my candidate: the guy who’s strategically silent on the wildly-popular streamer who’d gladly see my Israeli family members raped and beheaded, rather than campaigning with that streamer like Abdul El-Sayed did in Michigan. I unironically believe that, for Talarico, it took genuine moral courage to resist the whole momentum of his party’s youth even to this extent.

To earn my vote in the near future under these circumstances, all a Texas Republican would need to do is be somewhat sane or reasonable. He or she might affirm, for example, that racism is bad, that abortion is a woman’s choice, that Christianity is not the state religion of the US, that Covid vaccines work, that human emissions are worryingly changing the earth’s climate, and/or that Joe Biden won in 2020, while still being arbitrarily right-wing on taxes and other stuff. He or she could then simply wait for the Democrats to descend fully into the worldview of the masked hooligans who are currently setting France’s beautiful cities aflame, terrorizing its shopkeepers, and looting as many Louis Vuitton handbags as they can carry … all for Palestine, of course, and for the death of global capitalism, and for the violent overthrow of the scheming, money-grubbing, hook-nosed, international Talmudic … err, I mean “Zionists.”

What I’m trying to say is, it was a genuine achievement on the part of the Texas Republicans to fail to earn a single vote from me this cycle.

Terence Tao — An experimental AI-math challenge: using tenth discriminant bounds to explore arguments ruling out Siegel zeroes

In the spirit of my recent “Math 2.0” talk on new ways to use AI assistance to enhance the human understanding of mathematics, rather than substitute for it, I am using this post to propose an experimental challenge, inspired by the recent activity around excluding Landau–Siegel zeroes, as discussed in this previous post.

There is a well-known connection between Landau–Siegel zeroes and the tenth discriminant problem, which I will briefly recall here; an in-depth discussion on this problem can be found in this survey of Shafarevich. As far back as the work of Gauss, it was observed that there were nine discriminants {-d} whose rings of integers for the associated quadratic field {{\bf Q}(\sqrt{-d})} enjoyed unique factorization, namely

\displaystyle  d = 1, 2, 3, 7, 11, 19, 43, 67, 163.

Gauss believed this list of nine to be the complete list of such discriminants (the “class number one problem”), but this was only proven by Heegner in 1952 by introducing the concept of a Heegner point on the modular curve; and the above numbers are now known as Heegner numbers.

Prior to Heegner’s solution was the work of Heilbronn and Linfoot in 1934, who used what we now call the Deuring–Heilbronn repulsion phenomenon to show that the existence of a tenth discriminant in the above list can be used to “repel” any further such discriminants, so that there was at most one further Heegner number beyond the nine already known. However, this argument was ineffective: no upper bound on this putative tenth discriminant was given, and so there was no obvious way to solve the class number one problem purely from this result.

There is a close connection to Landau–Siegel zeroes: if {d} is a Heegner number, and {\chi} is the quadratic character associated to this quadratic field, then the class number formula gives {L(1,\chi) = \frac{\pi}{\sqrt{d}}}, and with a bit more work one can produce a Landau–Siegel zero {L(\beta,\chi)=0} with {1-\beta \asymp \frac{1}{\sqrt{d}}}. For sufficiently large {d}, this is inconsistent with Siegel’s theorem; but the standard proofs of this theorem also relied on the repulsion phenomenon and were also ineffective. It was only in 1976 that Goldfeld gave an effective version of Siegel’s theorem that was enough to at least bound the tenth discriminant, given a suitable high rank elliptic curve. In followup work of Oesterlé, combined with a high rank elliptic curve of Gross and Zagier, the bound {d \leq e^{7000}} was obtained; using a later elliptic curve of Brumer and Kramer, proven to have high rank by Mestre, Oesterlé, and Serre, the bound was improved to {d \leq e^{55}}. See this survey of Goldfeld for more discussion.

But now we have a fair number of new (and effective) ways to rule out Siegel zeroes, either by establishing a quasi-Riemann hypothesis, or by some version of the argument in this previous post. In principle, each version of these arguments should also give a bound on the tenth discriminant {d} (without using Heegner’s solution to the class number one problem that rules out this discriminant). The task of making each of these estimates explicit enough to create such a bound is rather tedious for humans. However, it seems eminently suitable for AI.

Thus, the challenge I pose is, for each of the new manuscripts or digestions relating to either the quasi-Riemann hypothesis or the Landau–Siegel zero problem (or by some novel argument), to use an AI tool to work out an effective upper bound for a hypothetical tenth discriminant {d}, without using Heegner’s methods, and to make best efforts to optimize this constant. This serves several purposes:

  • If the threshold is low enough to resolve the remaining discriminants by direct computation, this would yield a new solution of the class number one problem — possibly one that is formalizable in Lean in a high quality fashion (suitable for instance for upstreaming to Mathlib).
  • By performing this exercise on each of the different writeups, we obtain a way to compare the “strength” of each such writeup (after performing whatever optimizations are available for each writeup), which could give insight as to the relative advantages or disadvantages of different arrangements of the methods.
  • The exercise of minimizing the upper bound may spur the creation of entirely new arguments to solve either the class number one problem, or the elimination of Landau–Siegel zeroes.
  • There are many previous “failed” attempts at excluding the Landau–Siegel zero. It is possible that some of them contain ideas that can be combined with the newer solutions to this problem to “repair” the proofs, or at least improve the bound on the tenth discriminant.
  • Efforts here may also help improve the state of knowledge on higher class number problems, which by the work of Watkins in 2004 is currently solved up to class number 100.

Furthermore, as both of these problems are already solved (for over seven decades, in the case of the class number one problem), there is little risk of such a competition inadvertently disrupting an ongoing research project.

I am therefore inviting interested readers to contribute in the comments any effective bounds on the tenth discriminant they can extract from either an existing argument, or a novel one, with any amount of AI use permitted for this challenge so long as it is disclosed. Note that the challenge is broader than simply getting the “best” bound overall amongst all possible approaches; I am also interested in what bounds one can extract from any specific approach, even if they are worse than, say, the bounds of Goldfeld or Oesterlé. In particular, “negative” results in which the bounds obtained from a given method end up being rather large are still scientifically useful pieces of information that are worth reporting. One could also explore other directions, such as bounds that avoid using extensive compute to squeeze out the maximal amount of optimization, but are instead clean enough that their arguments are human-verifiable.

Any large outputs should be posted as links rather than as plain text; for instance, pointing to a Github repository containing one’s work would be a reasonable way to submit an entry (but a human-generated summary should be provided in the main text of the comment).

I would ask contributors to not prioritize speed above quality; this is not intended to be a race regarding who is “first” to claim any given bound. The spirit is intended to be collaborative rather than competitive: think of a Polymath style project, updated for the AI era. In particular, as with traditional mathematical research, it would be appropriate to build upon previous contributions to obtain an improved bound for a given proof technique. (But in such cases, one should of course give appropriate attribution to the prior source.)

I will not insist on formal verification (e.g., in Lean) of the results, though I would ask anyone submitting a purely AI-generated solution to do enough due diligence to check the output (e.g., with an independent AI tool) before posting it here.

I am looking forward to the results of this experimental challenge, both for the mathematical insights gained, and for the lessons learned on how to crowdsource AI assistance in mathematics in a responsible fashion.

Proofs and Prompts — The Rules Cannot Change Only for Young Mathematicians: AI and the future of a mathematical career

Anonymous, Postdoc

SERIES · As application deadlines approach, Proofs and Prompts is publishing a series of posts from 19 to 23 October for people considering a PhD, doing a PhD or looking for a postdoc: guidelines, discussions and speculation about what to do and what careers in mathematics will look like. This post is one of them. Each is written independently and reflects only its authors’ views. All posts in the series

AI assistance disclosure: AI was used to translate my draft into English, revise its language and organization, assist with literature searches, and suggest relevant quotations and statistics. The personal experiences and central concerns originate in my draft.

I am a postdoctoral mathematician working in partial differential equations, and I love what I do. I have preferred doing mathematics to expressing opinions in public, but the rapid changes of recent months have made that difficult.

I am writing neither to defend a complete ban on AI nor to celebrate its unrestricted use, but because I no longer know what rules I am expected to follow, what work will count as my own, or how today’s decisions will affect my career.

For an established professor, uncertainty about the future may be a subject for an interesting essay; for a doctoral student or postdoc, it can determine whether years of work lead to a job. The same advice does not carry the same risk for everyone.

My concern is not only what AI can do to mathematics, but what mathematicians and institutions are choosing to do to one another during this transition.

1. We are told that priority will matter less, but the race suggests otherwise

A recurring message in the recent debate is that recognition should move from being first toward understanding proofs, explaining their ideas, and making them useful to others.

In Mathematics in the age of AI, Terence Tao argues for less emphasis on proof generation and being first. Amit Harlev goes further: “when a result is proven by an AI, priority should carry no reward.” Timothy Gowers predicts that the credit system will collapse, while defending credit as long as careers depend on it. Benoit Henry questions whether a theorem belongs to whoever obtains it first when someone else could quickly do so with a similar system. [1, 2, 3, 4]

Bryna Kra offers a concrete proposal: “Journals need to distinguish and credit the roles of discovery, proof, formalization and explanation.” Grant Sanderson observes that “every AI-generated proof is born an unsolved exposition problem.” [5, 6]

I welcome greater credit for explanation, but cannot behave as though that transition has happened while the consequences of being second remain uncertain. A postdoc cannot pay rent with a prediction that exposition will eventually become prestigious.

The possibility that another person or laboratory could obtain a proof quickly can intensify the pressure to announce first, even as we are asked to slow down, check the literature, understand everything, and write carefully.

Nor do I accept that mathematics was always about understanding rather than solving problems: I value both learning a beautiful argument and finding one that did not previously exist. I do not want either experience dismissed merely because the other may be easier to preserve.

The familiar name “Fermat’s little theorem” reminds me that discovery, proof, and naming are not the same thing. Historical names offer no reliable rulebook for present-day authorship; we need to distinguish priority, authorship, attribution, and understanding explicitly.

2. What exactly does an AI-generated proof entitle its producer to claim?

Jihao Liu states the practical dilemma unusually clearly:

“Consider the following situation. I use AI to produce a paper whose result is important. What should I do?

  1. I post the paper to arXiv. Then I am criticized for not having verified the paper in detail. This goes against my values as a mathematician.
  2. I do not post the paper anywhere. But what if someone else obtains the result and posts it before me? In that case I lose the credit.” [7]

He posts some machine-checked, not yet human-verified papers on a separate webpage rather than arXiv, and requires a timestamp when recognizing prior independent work. [7]

Liu is frank about protecting priority, but the order troubles me: secure the claim first, complete verification and repair attribution afterward. Treating credit as his to grant strikes me as cynical. His offers of shared credit and coauthorship recognize the value of checking, simplifying, and explaining, but leave unclear what the announcement reserves and what later contributors can earn. [7]

What credit has the initial producer earned before these other contributions have been made? Does a public timestamp establish priority for a theorem, a candidate argument, or merely a generated document? If the proof is correct but its attribution incomplete, what is owed to the people whose ideas supplied most of it?

Marco Trombetti’s ProofForum proposal distinguishes generating, checking, repairing, simplifying, and explaining without endorsing Liu’s entire policy: “verification could itself become a visible mathematical contribution.” Recognition need not stop with the generator, and credibility can develop through public examination. [8] That may be useful, but a record of contributions is not yet an agreed system for allocating jobs, prizes, publishing rights, or theorem names.

Ruodu Wang supports human understanding and rewriting, but identifies the incentive problem: “Being the second to solve a problem has low or no value.” His model rewards posting AI output immediately over taking time to understand and rewrite it. [9] Even a reduced but positive reward for first place preserves that disadvantage if second place earns nothing; Wang’s argument is that careful work needs changed incentives, not advice alone. [9]

Removing priority creates another difficulty: junior researchers depend on the problems they solve, rather than the established reputations and other recognized roles of senior mathematicians. Wang writes: “I do not see a good system of evaluating junior mathematicians.” A new ideal is not yet a viable career. [9]

We cannot preserve the reward for speed, demand slow and careful work, and leave the people with the least job security to absorb the conflict.

3. The Navier–Stokes dispute: different results, unresolved standards

The September controversy involving Tristan Buckmaster, Levent Alpöge, and OpenAI left me with a bitter feeling. As a PDE researcher, I wanted to understand both the mathematics and its implications for research practice.

The mathematical claims should first be kept distinct. OpenAI’s September 8 announcement claimed a smooth-forcing Navier–Stokes blow-up result establishing alternatives C and D of the Millennium Prize formulation, alongside a separate unforced Euler result. It distinguishes these from Alpöge and Buckmaster’s forced Euler work and denies that their unpublished work or recent Codex prompts influenced its system. These are OpenAI’s stated claims and account. [10]

In the Q&A of Buckmaster’s September 23rd NYU talk, he says: “Those physical mechanisms that I can explain to you guys came out from LLM.” In his account, AI supplied important mechanisms while human expertise directed the search and helped reconstruct the argument. A label such as “Alpöge–Buckmaster, 2026” therefore needs a clear account of what the researchers proposed, what the systems generated, and who verified and rewrote the proof. [12]

He also describes working with Alpöge through internal models: “it’s not just internal models it’s internal compute.” His point that many agents can matter as much as a better model distinguishes their resources from an ordinary subscription. [12]

Buckmaster questions credit based on “who does something the fastest” and says: “I think this race dynamics doesn’t make sense.” WIRED reports that he released unfinished papers to get ahead of OpenAI’s announcement and accepted responsibility for cleaning them up. Wanting priority to matter less while protecting work under unchanged rules is understandable—and precisely the dilemma younger mathematicians face. The question is not whether one researcher should have solved the incentive problem alone, but whether the community can advise young mathematicians to leave the race while continuing to reward those who enter it. [12, 11]

As of 1 October, more than three weeks after the 7 September announcement, I had not found a revised exposition of the forced Euler proof that resolved my readability concerns. Expecting a world-class fluid dynamics expert such as Buckmaster to produce one does not settle what recognition the initial release deserves. [27]

If an unfinished announcement preserves recognition while a readable proof follows later, is the same option open to a doctoral student or postdoc? What standard of verification and exposition must be met before release, and what recognition remains available to someone who waits?

Buckmaster’s talk and NYU’s announcement explicitly credit Diego Córdoba and Luis Martínez-Zoroa’s program and strategy, yet public attention can favor the final announcement over the work that made it possible. [12, 27]

Neither Isabella Ward’s 19 September WIRED article, “Mathematicians Feel Threatened by AI. They Can’t Quit It,” nor the 8 September OfficeChai report, “OpenAI Says It Didn’t See Any Of Buckmaster And Alpöge’s Work While Resolving Navier-Stokes,” names Córdoba or Martínez-Zoroa. My concern is that press coverage of priority disputes in the AI era will tend to focus on who obtained or announced a result first, while overlooking the foundational mathematical work—and the people behind it—that made those AI-assisted discoveries possible. [11, 28]

4. This is not an abstract problem for me

I have checked and rewritten an AI-generated proof of a problem I had not worked on for roughly ten years, but have not published it. A group I will not name is pursuing the same question; as far as I know, they have not resolved it, and my argument appears to take a different route from their earlier attempts. Should I post it with a detailed account of the AI contribution, contact the group first, or offer collaboration? If I present the result at a conference, should I write “Theorem [my name, 2026]” on the slide, and would publishing it help my career, damage my reputation, or both?

I am not asking to claim someone else’s ideas, but what credit checking and rewriting earns; that cannot depend on which influential mathematician is asked.

Meanwhile, I am finishing a substantial article developed over about a year with pen and paper, not with AI. Almost daily, I fear being scooped by someone, perhaps using AI, who posts first: my understanding would remain, but the publication opportunity and recognition for a year of independent work might not.

Antonio Auffinger’s Open problems, open mathematics warns that others can quickly complete a publicly shared strategy, making unfinished ideas risky to share. His call to reshape incentives aims to protect openness for the least secure researchers. [13] I want to continue sharing ideas, asking colleagues questions, and doing careful work without making secrecy, haste, and suspicion the rational way to survive.

5. Recognition, jobs, and the cost of disclosure

Another part of the debate makes these choices even more difficult: some mathematicians do not merely question the value of AI-generated papers, but predict reputational damage for AI users or propose institutional preferences against their work.

In Where I Stand on AI, Vladimir Lazić predicts that attaching one’s name to a partially AI-produced paper can destroy a mathematician’s reputation. Addressing researchers without tenure, he writes:

“you will never get tenure, unless you are being pushed by someone in your camp who has tenure.” [14]

Although this is a prediction rather than evidence about hiring committees generally, a junior researcher cannot ignore the possibility that some evaluators share that attitude.

Donatella Iacono, explicitly following Lazić’s principles, states: “I do not support hiring of academic staff who use AI as a substitute for their own work.” She takes the same position on supervising doctoral and postdoctoral researchers. [32]

Max Weinreich goes beyond predicting reputational consequences: in The crisis of AI-generated mathematics, he proposes “reserving hire lines for mathematicians who eschew AI” and “valuing AI-free papers more highly in tenure promotion.” These are proposals for allocating opportunities differently, not merely expressions of a personal preference. [15]

Atticus Stonestrom makes a direct proposal about access to publication:

“Traditional journals should ban papers in which AI has played a coauthor-level role, and new venues should be established for the publication of such papers.” [16]

Without a ban, Stonestrom proposes distinguishing such papers and capping their annual publication. He cites authorship and scarce refereeing resources, acknowledges that restrictions may encourage concealment, but argues that this should not determine standards. Even a carefully checked paper could be excluded from a traditional journal. [16]

A young researcher does not need a profession-wide ban to find these positions alarming: a few editors or hiring-committee members can have a decisive effect on a career. Honest disclosure may carry lasting consequences when it can reduce recognition or make a paper ineligible for a journal.

Martin Hairer instead argues that “articles are judged on their merits, independently of the tools being used” and that disclosure should not automatically reduce a paper’s value, while retaining human scrutiny, understanding, and writing as requirements. [17]

What should a postdoc make of these competing messages: use AI responsibly and disclose it, avoid it to demonstrate independent ability, use it or fall behind, yet risk losing recognition by doing so? These are not small differences in taste when employment is at stake.

I have heard colleagues describe the strongest anti-AI views as resistance to an inevitable technology, while others say they reflect a larger, quieter part of the profession. I do not know which claim is correct, since neither a collection of essays nor my conversations establishes what most mathematicians believe.

What is already visible is uncertainty about the consequences of honesty, and that uncertainty deserves an institutional response.

6. What the publication and disclosure data actually show

The data show rapid change without establishing how much AI use is undisclosed or why.

Tammy Kolda and Daniel Appelo count 6,307 primary-mathematics arXiv announcements in August 2026, up 2,785 from 3,522 a year earlier—about 79%, versus 43% across arXiv. [18]

Bar chart of new arXiv announcements with mathematics as the primary category: 3,522 in August 2025 and 6,307 in August 2026, an increase of 79.1%.
Figure 1. New arXiv mathematics announcements, using the primary-category counts reported by Kolda and Appelo. Re-created from their data. [18]

Benoit Henry reports single-author counts of 1,174 and 2,603 for those months (about 122% growth), with 809 later papers mentioning AI. He cautions that the counts are uncertain; single authorship is not evidence of AI use, and an AI mention is not necessarily a carefully classified disclosure. [4]

Xiaoshn Nee, Haobo Zhong, and Xiaomin Ni find growth in 29 of 30 primary mathematics categories; the share of active author units posting at least five papers in January–August rose from 2.45% in 2025 to 3.80% in 2026. [29]

Tara Abrishami’s Epoch AI analysis finds that disclosures of any AI use rose from 3.89% in April 2026 to 25.25% in August (1,453 of 5,754 papers); 337, or 5.86%, disclosed substantial research contributions. The broader category includes writing, computation, and literature review. [19]

Line chart of the share of examined primary-math preprints that disclose AI use, by first-submission month from January to August 2026. Any disclosed AI use rises steeply from June, reaching 25.25% in August; disclosed substantial research contribution reaches 5.86% in August.
Figure 2. Voluntary AI-use disclosures in the examined math preprint corpus. Re-created from Abrishami / Epoch AI, with attribution (CC BY). These are not estimates of all undisclosed use. [19]

Yet three quarters of Epoch’s August papers made no acknowledgment; this group grew from 3,260 in August 2025 to 4,301 in August 2026 (about 32%). Silence does not tell us whether AI was used, and differing corpora and counting conventions prevent simply combining the studies’ totals. [19]

In Kimball Martin’s August 2026 number-theory sample, 12.0% disclosed AI writing while 20.7% were flagged for apparent AI writing. The imperfect detector and unpublished scoring rule make this suggestive only; Martin warns that a score is not a verdict. [20]

These counts neither identify concealed use in individual papers nor prove large-scale concealment, but common sense suggests that incentives to publish faster, coupled with fear of penalties for disclosure, can encourage silence. I suspect some use goes unacknowledged partly because of stigma.

Harlev identifies the underlying incentive: evaluating declared AI work less favorably can punish honest researchers without reliably detecting undisclosed use. [2] We should therefore demand precise disclosures and fair evaluation together, since one without the other creates a predictable conflict.

7. Equal rules require more than equal advice

Access depends not only on whether someone chooses to use AI, but on the models, computing budget, and support available to them. OpenAI’s September account describes an internal model more capable than the public comparator, placing that work in a different setting from a postdoc’s ordinary subscription. [10]

I worry that personal connections to laboratories may become a research advantage. Does staying competitive now require knowing someone who can provide access to an internal system or a large computing budget? What happens to mathematicians who have neither those connections nor an institution able to buy equivalent resources? Such access must be visible in evaluation: a publication list should not conceal the difference between an individual subscription and large, privately supported searches.

The Advisory Group on Mathematics and Artificial Intelligence’s September 29 recommendations warn that proprietary models risk a “two-tier system” and unequal access to public models a “multi-tier hierarchy.” It calls for broad, equitable access. [21]

On 1 October 2026, Claude Max 20x and ChatGPT Pro 200 each cost US$200 monthly; the new ChatGPT Pro 500 costs US$500. Both highest-tier subscriptions total US$700 monthly, or US$8,400 annually, before taxes, exchange charges, and separate computing costs. [30, 31]

Across developing countries and lower-paid academic systems in developed countries, stipends and salaries may leave little for these subscriptions after living expenses, especially when researchers personally fund multiple services. An expense routine for a well-funded department may be unsustainable for an equally capable mathematician elsewhere, rewarding institutional resources and personal finances rather than talent, effort, or the quality of research questions.

Researchers should not have to choose between living expenses and tools increasingly treated as necessary. Institutional support helps, but identical prices do not mean equal access, and subscriptions do not fund thousands of parallel agents.

The Leiden Declaration links AI use to human responsibility, transparency, and its effects on the profession; these principles must apply equally to researchers with and without privileged access. [22]

Orwell’s Animal Farm comes to mind when formal equality coexists with unequal opportunities: I do not want one standard for insiders and another for outsiders, or strict rules for students with exceptions for established names.

8. What future are we offering PhD students?

I welcome the Harvard summit on doctoral education in the age of AI. Its September 17–18 meeting brought together 24 mathematicians, produced recommendations for departmental discussion, and explicitly thanked the graduate students and postdocs who participated in a panel. [23]

Consultation, however, is not the same as an ongoing role in decisions. How will students and postdocs participate in setting the rules that govern their training and evaluation? Who will represent people outside the institutions already most influential in this debate?

The report favors demonstrated mastery over the dissertation alone and says it “need not be a requirement for the thesis to have recorded the first proof.” This may protect students whose work is unexpectedly overtaken, but protection within a PhD program does not automatically carry into the job market. [24]

If an adviser asks a student to wait until an AI-generated argument is fully understood, and someone else posts a less readable version first, will the student still receive comparable recognition? Will thesis and hiring committees use compatible standards?

There can be good educational reasons to restrict tools while students learn a skill; equal treatment need not mean identical training for students and experienced researchers, but the distinction must be explained, bounded, and accompanied by protection against resulting disadvantages.

Senior mathematicians should ask what research opportunities they are preserving for students. If a problem can now be explored quickly using AI, should every such opportunity become another paper on an established researcher’s list, or could some become genuinely collaborative training projects? This concerns mentorship when the supply of attractive projects may change rapidly, not a demand that senior researchers stop research.

Above all, what life are we inviting a talented mathematics graduate to pursue? Many of us entered the subject because we wanted to experience the struggle and joy of discovery: working through failed ideas, finding the right argument, and reaching a moment of understanding through our own effort.

Jonny Evans explains why research produces more than a paper: “The ‘output’ is a person who understands something better,” someone who can carry that understanding into research and teaching. I share his concern that more results do not necessarily mean more capable mathematicians. [33]

Teaching, exposition, and verification are already part of the mathematics I love, but a career centered on checking machine output, teaching calculus, linear algebra, and differential equations to engineering and computer-science students, and explaining results generated inside commercial laboratories may not appeal to people who hoped to become researchers. Calling that concern nostalgia does not answer it.

I fear losing both discovery and professional security while being told that a more demanding system of oral assessments and repeated demonstrations of understanding is the solution. Such assessments may be appropriate, but they do not, by themselves, offer a positive account of the career that follows.

A field that fails to attract and support its next generation cannot preserve itself through inspiring statements alone.

9. What institutions need to say clearly

What I need from the people who hire, promote, edit journals, award grants, and supervise students is not another assurance that mathematics will always matter, but practical answers.

Ben Antieau puts one proposal plainly: “Do not recruit, hire, promote, or praise based on the number of papers.” Daniel Litt argues that sustained mathematical discussion and talks can demonstrate understanding better than papers alone. Henry similarly asks hiring committees to stop counting articles. [25, 26, 4]

These proposals need to become public rules before researchers can rely on them when choosing projects, tools, or publication venues.

I want clear answers in six areas.

Permitted use and responsibility. Which uses of AI are acceptable in research, dissertations, and submitted papers? How do the rules distinguish language editing, coding, literature searches, suggested lemmas, generated proofs, and largely autonomous work? What must every named author understand and be able to defend?

Release and priority. May someone release a proof that is not human-verified? Does a Lean-checked proof have a different status? Is understanding the broad strategy sufficient, or must the details be checked before release? What priority, if any, attaches to an unfinished write-up accompanied by a promise to improve it?

Authorship and attribution. What contributions justify authorship, and what contributions require a different form of recognition? How are the people who supplied prior methods, directed the search, repaired the proof, formalized it, or explained it credited? What must happen when the initial attribution is incomplete?

Hiring, promotion, and publication. Will good, selective mathematics journals accept AI-generated but human-verified proofs under the same standards as other research papers? How much original human input will they require? Will a clear explanation, simplification, or independent reconstruction of an already announced AI result satisfy their standards of originality and significance, or be excluded as exposition? Will those requirements be public before authors invest months in a project?

Will hiring and promotion committees continue to expect the same quantity of publications, journal prestige, citation counts, and h-index as before—or raise those expectations because AI can accelerate production? If understanding and exposition are to count more, what evidence will be accepted in place of those measures, and will it lead to comparable professional opportunities? Will a mathematician working without AI be judged against AI-assisted output rates? Will someone who discloses careful AI use be penalized for doing so? How can candidates challenge decisions based on standards that were never announced?

Training and protection. How will students retain opportunities for independent discovery? How will a student who follows careful verification rules be protected from the resulting delay? How will institutions recognize substantial work that loses chronological priority?

Access and implementation. Who will fund the tools that new expectations require? How will unequal model access and computing budgets be considered? Which rules apply across institutions, when do they begin, and how will students and postdocs participate in reviewing them?

I am asking not for a universal numerical formula for mathematical worth, but for public standards that guide decisions without changing according to a person’s reputation.

10. The future should not be decided over our heads

For the first time, I am seriously considering leaving mathematics—a painful sentence to write after almost twenty-five years of passion, thought, and effort. What makes me consider leaving is not that a machine can do something I cannot, but that I no longer trust the profession to offer a fair and intelligible path forward.

What troubles me most is the possibility that established researchers will keep the advantages of the old system while younger people accept the obligations of a new one. Even when individuals act in good faith, the appearance of that double standard is damaging and should be addressed through transparent rules rather than dismissed as anxiety about technological change.

What I am asking for is a profession in which careful work is not punished for being slow, honesty is not punished for being visible, and access to powerful tools is not confused with mathematical merit.

I would welcome an emergency international meeting, with the reach and seriousness of an ICM, devoted to these questions. It should include doctoral students, postdocs, mathematicians from less wealthy institutions and countries, journal editors, hiring committees, and funding bodies—not only the people who already have the most secure positions. Its aim should be concrete, revisable standards for research, credit, training, and careers, together with a timetable for putting them into practice.

No meeting can settle every question permanently, but we can do better than leaving young researchers to discover the real rules only when an application is rejected.

My deepest fear is not that AI will destroy the career of a mathematician, but that mathematicians will make it unlivable through unequal rules, opaque incentives, and a failure to protect the people who come next.

I do not yet have a settled position on every use of AI in mathematics, but I do have a clear position on fairness: the rules cannot change only for the young.

Sources and references

[1] Terence Tao. Mathematics in the age of AI. arXiv:2608.16753, 17 August 2026.

[2] Amit Harlev. Dear conferences, journals, and hiring committees: don’t wait for everyone else. Proofs and Prompts, 25 September 2026.

[3] Timothy Gowers. Why I didn’t sign the Fields medallists’ letter. Gowers’s Weblog, 17 September 2026.

[4] Benoit Henry. The Loss of Singularity. Proofs and Prompts, 28 September 2026.

[5] Bryna Kra. Deep theorems were scarce and difficult and so became an effective mechanism to identify deep thought. AI has broken this system. What’s New, 13 September 2026.

[6] Grant Sanderson. If math is more than proof, we need to better celebrate the rest of it. What’s New, 18 September 2026.

[7] Jihao Liu. About the page of AI-generated results not verified by a human. Author’s website, undated.

[8] Marco Trombetti. ProofForum: Keeping AI-Generated Mathematics Human. Proofs and Prompts, 22 September 2026.

[9] Ruodu Wang. The AI-assisted mathematician’s dilemma. Proofs and Prompts, 28 August 2026.

[10] OpenAI. On the Navier–Stokes Millennium Prize Problem. 8 September 2026; updated 10 September 2026.

[11] Isabella Ward. Mathematicians Feel Threatened by AI. They Can’t Quit It. WIRED, 19 September 2026.

[12] Tristan Buckmaster. [Seminar on AI-assisted fluid dynamics]. YouTube video, 2026.

[13] Antonio Auffinger. Open problems, open mathematics. What’s New, 22 September 2026.

[14] Vladimir Lazić. Where I Stand on AI. August 2026.

[15] Max Weinreich. The crisis of AI-generated mathematics. arXiv:2608.02859v1, 3 August 2026; text updated 5 August 2026.

[16] Atticus Stonestrom. A proposal for mathematics journals in the age of AI. Undated essay.

[17] Martin Hairer. Writing mathematics in the age of AI. Proofs and Prompts, 7 August 2026.

[18] Tammy Kolda and Daniel Appelo. A Breakdown of arXiv Submissions in Mathematics. The Loss Function, 21 September 2026.

[19] Tara Abrishami. In August, 25% of math preprints acknowledged AI use, up from 4% in April. Epoch AI, 18 September 2026.

[20] Kimball Martin. AI use in arXiv NT papers. 5 September 2026.

[21] Advisory Group on Mathematics and Artificial Intelligence. Responsible Release of AI-Generated Mathematics. 29 September 2026.

[22] Leiden Declaration working group. Leiden Declaration on Artificial Intelligence and Mathematics. June 2026.

[23] Harvard Center of Mathematical Sciences and Applications. Summit on PhD Math Education in the Age of AI. 17–18 September 2026.

[24] Participants in the Harvard CMSA summit. Report of Summit on PhD Math Education in the Age of AI. September 2026.

[25] Ben Antieau. Fast math/slow math. What’s New, 15 September 2026.

[26] Daniel Litt. A beginning for mathematics. 13 September 2026.

[27] NYU Courant Institute. Tristan Buckmaster Constructs Finite-Time Blowup for 3D Euler with Smooth Forcing. 14 September 2026.

[28] OfficeChai Team. OpenAI Says It Didn’t See Any Of Buckmaster And Alpöge’s Work While Resolving Navier-Stokes. OfficeChai, 8 September 2026.

[29] Xiaoshn Nee, Haobo Zhong, and Xiaomin Ni. The Generative AI Gold Rush in Theoretical and Computational Research. arXiv:2609.04872, September 2026.

[30] OpenAI. ChatGPT — Release Notes. 29 September 2026.

[31] Anthropic. What is the Max plan? Claude Help Center, accessed 1 October 2026.

[32] Donatella Iacono. Where I stand on AI. Author’s website, 2026.

[33] Jonny Evans. Statement on LLMs. Author’s website, undated.


Received 2 October 2026, revised 19 October 2026.

Proofs and Prompts — Is it fish love?

Tancredi Schettini Gherardini, postdoctoral researcher based both at the University and at the Max Planck Institute in Bonn.

This reflection starts with a parable I learnt from a recording of Rabbi Dr Abraham Twerski. He came across a young man who was clearly enjoying a fish that he was eating, and asked: ‘Young man, why are you eating that fish?’. And the young man answered ‘because I love fish!’. The Rabbi said: ‘Oh you love the fish, that’s why you took it out of the water and killed it and boiled it? Don’t tell me you love the fish; you love yourself, and because the fish tastes good to you, therefore you took it out of the water and killed it and boiled it.’

The message is that so much of what is usually called love is actually fish-love, i.e. we don’t love the object/person per se but how it/they make us feel. My intuition is that the nature of one’s love for mathematics is intimately related with their views on AI.1

What is it that drives a mathematician to persevere through pain and frustration until a conjecture is proven or disproven? Is it to establish that they are better than others? Is it the satisfaction which comes from reaching a goal that has required so much of their time and energy? Is it the pleasure of knowing the answer to a question they find really interesting? Supposedly, in practice, it will be a mixture of the three. But is there one which overweighs the other two? Is there one which should outweigh the other two?

The answer is deeply personal, and I shall not argue here whether one is better than another. My message is that to understand our own views on AI for mathematics, the most appropriate starting point is an introspective analysis of why we – not as a community, but we-ourselves – love mathematics. This might be a complicated and even disturbing process; but, as Aristotle said, “knowing yourself is the beginning of all wisdom”.

Let me articulate my argument in a way that is agnostic to the notion of what is a correct motivation for doing mathematics. If mathematicians are most concerned with (possibly interesting) answers to interesting questions, then it is quite hard to argue against the benefits of AI in the subject. One can argue about the negative consequences in the general picture that is wider than mathematics (like environmental damage, privacy issues, monopoly, increase of inequality and unemployment, not to mention the risk of extinction); these are all very serious and well-founded worries which would need many essays, and I shall not deal with them here.2

When restricting to the features that are more specific to our discipline, one can argue about the potential risks in mathematics, which I think mainly boil down to two aspects.

Firstly, losing some important habits and routines essential in the practice of doing good mathematics – mostly those which ensure a deep understanding of the material, such as insightful human interaction, long-term projects and frequent productive struggle, for instance. But, regarding this concern, we have all the tools to deal with it effectively. In fact, we can act upon it by following these good habits ourselves, adapting them in a meaningful way when needed, and transmitting them to the newer generations. To ensure that they keep being part of a mathematician’s workflow, we might require some adjustments on a few fronts, such as the publishing process (where it is desirable to cut out or at least flag AI slop), the hiring process, and many general criteria for judging the quality of a mathematician. This is not just completely in our hands, there is also (almost) complete unanimity: I have never heard any mathematician, optimistic or pessimistic about AI, ever saying that we should give up understanding as a fundamental part of the discipline. To summarise, the temptation of these tools might pull us unwillingly away from understanding, but this risk has already been identified and acknowledged by our community and we have the power to make practical changes discouraging and preventing misuse of AI; in fact a few of these changes have already been implemented and many are currently being discussed.3

The second risk, which I personally consider to be scarier, is that of mathematics losing appeal for young bright minds; once more, it is up to us to not let this happen, illustrating how AI can be embraced in a constructive way, without disrupting the essential features of our field and the understanding-related practices mentioned above. Maybe even more importantly, it is hard to believe that the conservative choice of refusing any use of AI could attract more smart kids to join our community.

As of today, I do not see bigger problems than these two, which are only potential. And so, what are the benefits?

Since a few months ago, most of us have had our own version of Namagiri Thayar. It does not reveal formulas in our dreams, like the Hindu goddess used to do with Ramanujan, but it does so while we are awake and sitting in front of our laptop.4
Our reaction to this fact seems a bit different from the one people had one hundred years ago: I did not find any references of mathematicians from that time complaining about these revelations, nor signing petitions for banning Namagiri Thayar from Ramanujan’s dreams. But now that we all have something equivalent, a different chord was struck in the collective consciousness of our community. A purely emotional one, I argue; because if one’s priority is really the progress of mathematics, then why not embrace this new reality, made of Ramanujan-like moments, driven by AI suggestions, constructions, and results, and Hardy-like moments, trying to make sense of these results, with rigour, clarity and sharp understanding. If one’s love for mathematics is a genuine strive for advancement, and not simply the fish-love of Twerski, then it is impossible to not see the incredible chance we have to push our explorations in this beautiful subject.

The opposite is true if one’s love for mathematics mainly comes from the way that mathematics makes them feel. The feelings of finding a new clever way around a seemingly insurmountable obstruction, constructing a special interesting object that no one had thought of, or proving an important theorem for the first time, are all very much at risk. Because that new argument, example, or proof, could be generated by an LLM operated by someone who may or may not, in many instances, be an expert in the subject; in that case, the emotions which usually come with the mathematical discovery/invention are just gone.

The truth is that inside everyone’s passion for mathematics, and inside everyone’s love for someone or something, there is often a component of genuine and unselfish love, inevitably mixed with some fish-love. We are humans, after all. But if the former prevails, and we are driven by the sincere admiration of the exquisitely intellectual activity that has led humans from a few primitive logical observations to the immense and sophisticated body of knowledge that we have today, we might live the advent of AI with more optimism.


Received 24 September 2026.

  1. Throughout this essay, I will use ‘mathematics’ to mean ‘pure mathematics’ and ‘mathematicians’ to mean ‘pure mathematicians’. Many of the considerations below apply in general, but not all of them. ↩︎
  2. Let me spend a few words on those global consequences which impact mathematicians as a part of society. The first one is the possible shortage of funding; as of today, theorems in mathematics are a perfectly inelastic good, and there is no good evidence to suggest they should change to be so. Concerning inequality, that is a real issue which should be dealt with; it might be mitigated by the improvement of open-weights models, but there is no guarantee. In any case, this social aspect is somewhat orthogonal to the one I would like to focus on, i.e. the development of mathematics itself. Regarding privacy and intellectual property, they are also real concerns, but it seems possible to deal with them. One can use incognito sessions for sensitive material and do a much more detailed literature search than just quoting the LLM’s output, respectively. ↩︎
  3. One might argue that a foreseeable future scenario is that in which we delegate all of our thinking to the machines. Once more, that is ultimately up to us, and not a very likely prediction under mildly optimistic assumptions. Finally, if that will really be the case, we will have bigger problems than worrying about mathematics… ↩︎
  4. With all the obvious caveats, of course, such as hallucinations (although very rare nowadays) and the abundance of AI slop. ↩︎

October 21, 2026

Tommaso Dorigo — Breaking The Shower Containment Taboo For Hadron Calorimeters

Breaking The Shower Containment Taboo For Hadron Calorimeters

Hadron calorimeters are particle detectors meant to measure the total energy possessed by high-energy subatomic particles that hit their front face and develop a shower of secondary particles inside their volume.

Tommaso Dorigo
Categories

October 20, 2026

Terence Tao — Simple and critical zeros of the Riemann zeta-function

[This is a guest post by Caroline Turnage-Butterbaugh. This blog post was initially written in a different file format and converted using AI. — T.]

Evidence in favor of the Riemann Hypothesis comes in many flavors. OpenAI’s proof of the quasi-Riemann Hypothesis is definitely one such flavor; however, in this post I will focus my comments on a different kind of evidence: lower bounds on the proportion of nontrivial zeros of the Riemann zeta-function on the critical line. Great strides have recently been made on this problem, both with and without the use of AI. Many thanks to Terry Tao for inviting me to discuss this problem and the recent breakthrough results.

Background. Let {s=\sigma+it}, where {\sigma,t} are real. The Riemann Hypothesis (RH) states that the nontrivial zeros of the Riemann zeta-function {\zeta(s)} have real part equal to 1/2. It arose out of Riemann’s foundational work, which led to proofs of the Prime Number Theorem by Hadamard and de la Vallée Poussin in 1896. If RH is true, then the error term in the Prime Number Theorem is essentially as small as possible.

Denote a nontrivial zero of {\zeta(s)} by {\rho = \beta + i \gamma}, where {\beta, \gamma} are real values and {0 < \beta < 1}. The critical line is the line {\Re(s)=1/2}, and often we will refer to a nontrivial zero on the critical line as a critical zero. Riemann asserted that {\zeta(s)} has infinitely many nontrivial zeros, and in 1914 Hardy proved that {\zeta(s)} has infinitely many critical zeros. (See Chapter 10 of Titchmarsh for several proofs of this fact.) Platt and Trudgian have numerically verified RH up to {3\cdot 10^{12}}, i.e. all of the nontrivial zeros for which {0 < \gamma \le 3\cdot 10^{12}} have {\beta = 1/2}. (The nontrivial zeros are symmetric about the real line, so it suffices to consider those zeros for which {\gamma >0}.) The authors also show that these zeros are simple, which we expect to be true of every nontrivial zero. We set {m_\rho} to denote the multiplicity of the nontrivial zero {\rho}.

The recent proportionality results making headlines give a lower bound on the quantity

\displaystyle  \kappa_0^s :=\liminf_{T \rightarrow \infty} \frac{N_0^s(T)}{N(T)}. \ \ \ \ \ (1)

Here, {N(T)} denotes the number of nontrivial zeros {\rho} for which {0 < \gamma \le T}, and {N_0^s(T)} denotes the number of zeros counted by {N(T)} which are both simple and critical, i.e. for which {m_{\rho}=1} and {\beta=1/2}. One can analogously define {N_0(T)} to count critical zeros and set

\displaystyle  \kappa_0:=\liminf_{T \rightarrow \infty} \frac{N_0(T)}{N(T)}.

The Riemann–von Mangoldt formula gives a surprisingly precise asymptotic formula for {N(T)}; for this discussion, it suffices to record that

\displaystyle  N(T)\sim (T/2\pi)\log T \qquad \text{as}\quad T\rightarrow \infty.

(Here and throughout, {f(x)\sim g(x)} means {\lim_{x\rightarrow \infty} f(x)/g(x) = 1} and {g(x)} is a positive function.) Recall that zeros of analytic functions are counted by the argument principle with their multiplicity. Therefore:

** It is important to keep in mind that we always count zeros with multiplicity.**

Previous key unconditional results on {\kappa_0} and {\kappa_0^s}. In 1942, Selberg proved that a positive proportion of the nontrivial zeros lie on the critical line. More specifically, he proved that there exists an effectively computable constant {c>0} such that {N_0(T)> c N(T)}. (In his 1947 PhD thesis, S. H. Min calculated {c} to be around {1/15000000}.) In 1974, Levinson introduced a new method to show that {N_0(T)> \tfrac{1}{3}N(T)}, i.e. at least {1/3} of the nontrivial zeros lie on the critical line. Soon after, he improved the proportion to {0.3474}. In 1979, Heath-Brown showed that Levinson’s method may be used to prove proportionality results on nontrivial zeros that are both simple and critical. Levinson’s method was extended by Conrey in 1989 to show that at least {2/5} of the nontrivial zeros of {\zeta(s)} are simple and critical. Over the years and with much effort and insight, members of the analytic number theory community have harnessed Levinson’s method to slightly improve these bounds, culminating with the work of Pratt, Robles, Zaharescu and Zeindler who proved in 2020 that at least {5/12} of the nontrivial zeros of {\zeta(s)} are on the critical line. The table below gives a snapshot of these results, with the precise proportions recorded.

Author(s)/Year {\kappa_0 >} {\kappa_0^s >}
Levinson (1975), Heath-Brown (1979) {0.3474} {0.3474}
Conrey (1989) {0.4088} {0.401}
Pratt, Robles, Zaharescu, Zeindler (2020) {0.417293} {0.407511}

A few key unconditional results on proportions of critical and simple zeros, prior to 2026.

Counting simple zeros under RH. In 1973, Montgomery published his groundbreaking work on the pair correlation of the zeros of {\zeta(s)}. As a corollary to his main theorem, which we will state below, he showed that under RH at least {2/3} of the nontrivial zeros are simple.

We now give a sketch of Montgomery’s argument for simple zeros. (To supplement the broad strokes which follow, I recommend Goldston’s expository paper.) This approach will lead us to the construction of Montgomery’s function {F(\alpha)}, and, in turn, the statement of his theorem concerning the pair correlation of the zeros of {\zeta(s)}.

Montgomery begins with the observation

\displaystyle  N_0^s(T)=\sum_{\substack{0<\gamma \le T\\\rho \text{ simple}}}1 \ge \sum_{0 < \gamma \le T}\left( 2-m_{\rho}\right). \ \ \ \ \ (2)

Note that since the argument assumes RH, the zeros are necessarily critical! The goal is to determine a constant {1\le c < 2} such that {\sum m_{\rho} \le c N(T)} so that, when combined with (2), we may conclude {N_0^s(T) / N(T) \ge 2 - c >0}. A key transition occurs after noting

\displaystyle  \sum_{0 < \gamma \le T}m_{\rho} = \sum_{\substack{0 < \gamma,\gamma'\le T\\ \gamma = \gamma'}}1. \ \ \ \ \ (3)

(Keep in mind that we always count with multiplicity.) The sum on the right-hand side is a double sum over {\gamma} and {\gamma'}, and with it pair correlation will soon enter the picture. Roughly, the idea is to find a nice function {r(u)} for which

\displaystyle  \sum_{\substack{0 < \gamma,\gamma'\le T\\ \gamma = \gamma'}}1 \le \sum_{0< \gamma,\gamma' \le T}r\left(\frac{\gamma-\gamma'}{2\pi/\log T} \right), \ \ \ \ \ (4)

where {r(0)=1} and {0\le r(u)<1} when {u\ne 0}. (Note that we have normalized the difference {\gamma-\gamma'} by {2\pi/\log T}, the average spacing between zeros around height {T}.) For {r(u)\in L^1}, define the Fourier transform by

\displaystyle  \hat{r}(\alpha) = \int_{-\infty}^{\infty}r(u)e^{2\pi i \alpha u}\,du.

Then if {\hat{r}(\alpha) \in L^1}, we have almost everywhere

\displaystyle  r(u)=\int_{-\infty}^{\infty}\hat{r}(\alpha)e^{-2\pi i \alpha u}\, d\alpha.

Suppose for the moment that we have a function {r(u)} satisfying the properties above. Then proceeding formally and ignoring error terms, we arrive at an inequality of the shape

\displaystyle  \sum_{\substack{0<\gamma,\gamma'\le T \\ \gamma = \gamma'}}1 \le \int_{-\infty}^{\infty}\hat{r}(\alpha)\sum_{0<\gamma,\gamma'\le T}T^{i\alpha(\gamma-\gamma')}\,d\alpha.

Montgomery showed how to estimate (a weighted version of) the inner sum on the right-hand side above by proving, under RH, an explicit formula relating the nontrivial zeros of {\zeta(s)} and the primes. This weighted sum is given by

\displaystyle  \begin{array}{c} F(\alpha)=F(\alpha,T) := \Big(\frac{T}{2\pi}\log T\Big)^{-1}\sum_{0<\gamma,\gamma' \le T} T^{i\alpha(\gamma-\gamma')} w(\gamma-\gamma'), \\ \text{where} \quad w(u) := \frac{4}{4+u^2}. \end{array} \ \ \ \ \ (5)

Note that {w(0)=1} and {w(u)<1} when {u\ne 0}. We may now state Montgomery’s Theorem.

Theorem 1 (Montgomery, 1973) Assume the Riemann Hypothesis. Then {F(\alpha)} is real, even, nonnegative, and, as {T\rightarrow \infty},

\displaystyle  F(\alpha) = \alpha + o(1) + (1+o(1))T^{-2\alpha}\log T

uniformly for {0\le \alpha \le 1}.

(That the theorem holds up to {\alpha=1} is due to Goldston and Montgomery.) There are scores of interesting things to say about this theorem and Montgomery’s pair correlation conjecture, but we will stay on task and return to the simple zeros argument. Assembling the chain of inequalities above and adjusting to accommodate the weight {w(u)}, we find that

\displaystyle  \frac{N_0^s(T)}{N(T)}\gtrapprox 2 - \int_{-\infty}^{\infty}\hat{r}(\alpha)F(\alpha)\,d\alpha. \ \ \ \ \ (6)

Under RH, one can evaluate the RHS using Montgomery’s Theorem, provided {\text{supp}(\hat{r})\subseteq [-1,1]} and positivity is maintained. Inserting the Fejér kernel

\displaystyle  r(u) = \left(\frac{\sin \pi u}{\pi u} \right)^2, \qquad \hat{r}(\alpha)=\max\{1-|\alpha|,0\}

into Montgomery’s theorem yields

\displaystyle  \sum_{0<\gamma,\gamma'\le T}\left(\frac{\sin(\tfrac{1}{2}(\gamma-\gamma')\log T)}{\tfrac{1}{2}(\gamma-\gamma')\log T} \right)^2w(\gamma-\gamma') \sim \frac{4}{3}\frac{T}{2\pi}\log T.

Thus, by (6)

\displaystyle  \frac{N_0^s(T)}{N(T)} \gtrapprox 2 - \frac{4}{3} = \frac{2}{3}.

In other words, under RH at least {2/3} of the nontrivial zeros are simple.

Counting critical zeros via pair correlation under a weaker-than-RH assumption. It was known among experts for some time that Montgomery’s Theorem could be made unconditional. Indeed, the starting point of the proof of Montgomery’s explicit formula is an unconditional explicit formula due to Landau from 1909 (see equation (9) on page 353). Setting {\rho = 1/2+\delta+i\gamma}, where {|\delta|<1/2}, the same arguments for Montgomery’s explicit formula and theorem carry through. That one could use an unconditional form of Montgomery’s Theorem to extract information about critical zeros was recently discovered by Siegfred Baluyot, Daniel Goldston, Ade Irma Suriajaya, and myself; henceforth BGST-B. In our first project we did not realize this capability of Montgomery’s method, and erroneously stated in the abstract “The method of proof neither requires nor provides any information on whether any of these zeros are or are not on the critical line where {\beta=1/2}.” In a follow-up paper we realized that, in fact, we could extract information on critical zeros using the pair correlation method, albeit upon an assumption weaker than RH. Roughly, we showed that if the nontrivial zeros of {\zeta(s)} are contained in a narrow vertical box centered on the critical line, then the pair correlation method shows that at least 67.25% of the zeros are both simple and critical. I’ll give a sketch of the argument, highlighting some of the key distinctions from Montgomery’s work. Portions of what follows below appear in our preprint.

In addition to making use of the multiplicity {m_\rho} of a nontrivial zero {\rho}, we use a quantity we refer to as the horizontal multiplicity of {\rho}. (This framework was suggested to us by Soundararajan and simplified our original classification of the ways in which {\gamma=\gamma'} can occur.) For {j} a fixed real number, the horizontal multiplicity {H(j)} is the number of nontrivial zeros of {\zeta(s)} on the horizontal line {s=\sigma + ij, 0 <\sigma < 1}, counted with multiplicity. Assuming RH, {H(j)} is either zero or the multiplicity {m_\rho} of the zero {\rho=1/2+ij}. Note that if {H(\gamma)=1}, then on the line {t=\gamma}, there is one simple zero on the critical line.

Let {\mathcal{Z}(T)} denote the multiset of nontrivial zeros of {\zeta(s)} for which {T < \gamma \le 2T}. We can partition {\mathcal{Z}(T)} into disjoint multisets of zeros according to their horizontal multiplicity:

\displaystyle  \mathcal{H}(k):=\{\rho \in \mathcal{Z}(T): H(\gamma)=k\}.

Consider the multiset {\mathcal{S}} of simple zeros in {\mathcal{Z}(T)} and the multiset {\mathcal{C}} of critical zeros in {\mathcal{Z}(T)}. Furthermore, note that

\displaystyle  \mathcal{H}(1) \subset \mathcal{S}\cap \mathcal{C}.

To obtain a lower bound on the proportion of simple and critical zeros, we begin with the following observation, which should be compared to (2):

\displaystyle  |\mathcal{S}\cap \mathcal{C}|\ge \sum_{\substack{\rho \in \mathcal{Z}(T)\\H(\gamma)=1}}1\ge \sum_{\rho \in \mathcal{Z}(T)}(2-H(\gamma)). \ \ \ \ \ (7)

Then, as in (3), we transition to a pair correlation argument upon noting

\displaystyle  \sum_{\rho \in \mathcal{Z}(T)}H(\gamma) = \sum_{\substack{\rho,\rho'\\ 0< \gamma, \gamma' \le T\\\gamma=\gamma'}}1. \ \ \ \ \ (8)

As in (4) we need to pick a kernel that maintains positivity. Tsang found a kernel that partially meets our needs; however, after rescaling for our setting, the positivity is only maintained provided the zeros {\rho,\rho'\in \mathcal{Z}(T)} are in a thin box centered on the critical line such that {|\beta-\beta'|< b/\log T} for some {0<b<1}. Assuming this condition, we may use the unconditional version of Montgomery’s Theorem (see equations (3.2) and (3.3) in our preprint) to bound from above the contribution of the right-hand side of (8) in terms of the Tsang kernel. In particular, choosing {b=0.001} yields {\kappa_0^s > 0.67250}.

Counting critical zeros via pair correlation unconditionally. On August 10, 2026, Anthropic announced that an unreleased research model of Claude had connected the BGST-B approach above with a 2000 paper by Bombieri to unconditionally prove that {\kappa_0^s > 0.67250}. The result was soon after verified by Alpöge and Furman, two mathematicians at Anthropic. Then, on September 2, 2026, Lamzouri announced a new, conceptually simpler proof of the same result. The entire preprint is very nicely written with helpful clarifications and remarks; in particular, Lamzouri takes care to compare/contrast his approach to that of Claude. With all of this in mind, I will focus this discussion on Lamzouri’s key ideas.

Lamzouri points out that the BGST-B approach cannot be made unconditional by merely finding a better kernel {K} at the transition

\displaystyle  \sum_{\substack{\rho,\rho'\\ 0< \gamma, \gamma' \le T\\\gamma=\gamma'}}1 \le \sum_{\substack{\rho,\rho'\\0<\gamma,\gamma'\le T}}K\left(\frac{i(\rho-\rho')}{2\pi/\log T} \right). \ \ \ \ \ (9)

Lamzouri, in fact, avoids this transition altogether by changing the mechanism with which simple and critical zeros are identified. As he helpfully writes on page 5,

Our key idea is that one can bypass the inequality [(9)] and directly prove, for a large class of kernels {K}, that the number of simple real elements of a finite multiset {\mathcal{Z}} which is invariant under complex conjugation is

\displaystyle  \ge 2\sum_{z\in \mathcal{Z}}1-\sum_{z,s\in\mathcal{Z}}K(z-s)^2

without requiring that the individual off-diagonal terms {K(z-s)^2} be non-negative.

Instead of setting {\mathcal{Z}(T)} to be the multiset of nontrivial zeros for which {0<\gamma \le T} as in BGST-B, he takes it to be the multiset

\displaystyle  \mathcal{Z}_T:= \left \{\frac{i(\rho-1/2)}{2\pi/\log T}: 0 < \gamma \le T\right\}.

This is such a clever idea! This multiset is invariant under complex conjugation, i.e. if {z\in \mathcal{Z}_T} then {\bar{z}\in \mathcal{Z}_T} and {m_{\bar{z}}=m_{z}}; its real elements are those with corresponding zero satisfying {\beta=1/2}; its real and simple elements are those with corresponding zero being critical and simple. As Lamzouri notes in Remark 2.2, “the square [i.e., in {K(z-s)^2}] is also naturally adapted to the Hilbert space argument in the proof [of Proposition 2.1] and to the use of Bessel’s inequality.” This new framework allows Lamzouri to bypass the portion of the previous arguments that required an assumption on the location of the nontrivial zeros.

Concluding remarks. Since the breakthrough results by Anthropic and Lamzouri, subsequent minor improvements have been made. (I will refrain from quoting the strongest result at the time of writing, since it will likely be out of date by the time this appears!) It is important to keep in mind that even if we increased 67.25% to 100%, the Riemann Hypothesis would not be solved. (Refer back to the precise definition of {\kappa_0^s} which appears in (1).) Nevertheless, the old and new ideas which have come together to realize these breakthrough results have expanded our understanding not only of the nontrivial zeros of the Riemann zeta-function, but, more broadly, of how different techniques were used, pushed, and molded to breathe new life into this problem.

Terence Tao — Mathematics is a subject for the young

[This is a guest post by Tristan Buckmaster. This blog post was initially written in a different file format and converted using AI. — T.]

This blog post expands on a theme mentioned at the end of my recent talk at the Institute for Advanced Study on October 19.

I would like to thank Matei Coiculescu, Jaume de Dios Pont, Nestor Guillen, Bryna Kra, Terence Tao and Rachel Ward for their valuable comments and suggestions.

It is often said that mathematics is a young person’s game, and that mathematicians do their best work early in their careers. I believe this is about to become true in a completely different sense. Mathematics is changing faster than at any point in its history. Today’s graduate students and postdocs will shape its future. Our responsibility is to protect their ideas and recognize their contributions.

In my statement on September 7th, the night Levent Alpöge and I released our Euler result and the day before OpenAI announced its Navier–Stokes result, I wrote that we had reached a Deep Blue–Kasparov moment. When Deep Blue beat Kasparov in 1997, the headline was that a machine had surpassed one of the greatest chess players of all time. Beyond just marking the moment a machine eclipsed human intellect, I chose this analogy because of the nature of the machine itself. Deep Blue was a purpose-built IBM supercomputer, entirely inaccessible to the general public. Today a program on a mobile phone plays far stronger chess than Deep Blue ever did.

This is where I think mathematics is now. OpenAI’s proof reportedly required the coordination of 10,000 agents over 88 hours, at an estimated cost in the millions to solve a problem with a $1 million bounty. At present, computation on this scale is entirely out of reach for the wider mathematical community. However, given the exponential growth in capabilities paired with decreasing costs, such a comparable computation may soon be more broadly accessible.

The question is no longer whether machines can do research mathematics, but how the subject will change as a result.

Chess did not die with the advent of modern chess engines. Engines democratized high-level preparation, resulting in the most globally diverse generation of top players ever. When I told a reporter that “the game is up,” I meant to describe the end of the academic rat race, the race to be the first to resolve a famous open problem is over. Mathematics as a subject is not.

Mathematics differs from chess in one important way, though: it is not performative. Chess survives partly because people love watching humans play. I am not going to convince anyone to watch two Fields medallists duke it out on a livestream proving a theorem. What gives it lasting relevance is something else: human understanding.

Suppose that tomorrow a machine certifies a proof of the Riemann hypothesis — whether with pages of AI slop or via a Lean file. No one doubts that the Riemann hypothesis is true. A certification would convert thousands of conditional theorems into unconditional ones. Mathematicians would still be left with the question: why is it true? De Toffoli and Duede captured this perfectly with their reference to Deep Thought, the computer in The Hitchhiker’s Guide to the Galaxy that analyzes the meaning of life for 7.5 million years and returns the answer “42.”

Mathematics has never been a list of true statements. Certifying a result settles the question, not the search for understanding.

Bridging mathematics and physics: One area I see as an exciting prospect for applying modern AI systems is the intersection of mathematics and physics. Indeed, I do not believe it is a surprise that some of the most exciting results to come out of AI so far have been in mathematical physics. Historically, mathematics and physics were inextricably linked, each serving as inspiration for the other: Newton developed calculus to formulate classical mechanics, Fourier analysis grew out of the study of thermal diffusion, Riemannian geometry supplied the mathematical underpinning of general relativity, and the needs of quantum mechanics shaped functional analysis. In the past decades, however, mathematics and physics have diverged. Physics is driven by heuristic arguments that are not true in the strictest sense, but are morally true and allow one to arrive at the correct answer. Quantum field theory is the standard example, where renormalization and the path integral make remarkably accurate predictions while still lacking a rigorous foundation. Closing the gaps in physical derivations is immensely challenging, and this is a key reason for the divergence of the fields. Rigorous derivation is not just an exercise in pedantry. It points to gaps in the physical theory, identifies the precise regimes and time scales on which an effective description is valid, and provides clues towards a more complete theory.

In years preceding the advent of AI in mathematics, a beautiful example of success in this pursuit, is Deng and Hani’s derivation of the wave kinetic equation as a large box limit of the nonlinear Schrödinger equation. Later, with Ma, they gave an analogous derivation of the Boltzmann equation from hard-sphere dynamics for as long as the Boltzmann solution exists, resolving Hilbert’s sixth problem for rarefied gases. The combinatorial analysis behind these results is a tour de force, and it took years of work. LLMs could potentially allow us to carry out such a program for other effective theories, where doing it by hand would frankly be out of reach. Ultimately, one could hope that LLMs will allow us to extend this standard of rigorous proof to all branches of the physical sciences.

Protecting our ideas: Currently, there are some fundamental structural problems in terms of how AI companies interact with the mathematical community.

AI companies, who strip mine our data, including unpublished work, private notes and research grant applications, have an egregious conflict of interest in competing against their own customers with unlimited resources and internal models unavailable to the public — this is not confined to mathematics but applies more broadly. By OpenAI’s own account, its push on the Millennium problems was spurred by rumors that a rival had solved two of them — demonstrating that caution, due diligence, and basic ethics can be cast aside simply to avoid being one-upped by a rival.

On October 6th, OpenAI released hundreds of manuscripts with proofs that were mostly unreadable and in some cases false. In the release, they misleadingly claimed that the work took on average three hours of computation on a single agent: they later admitted that they did not count numerous failed attempts at the problems as well as previous work done by other agents — rendering the three hours claim essentially meaningless. Again, OpenAI did essentially no due diligence, failing to investigate whether once again they may be building on the private, unreleased work of their customers, some of whom were graduate students and postdocs who were literally days away from releasing their own work.

In August, OpenAI claimed that such a dump would be `distasteful’, that their `main focus is shipping great models so everyone can use them to make discoveries of their own’. After Navier–Stokes, OpenAI had teased us with supposed solutions to additional Millennium problems, yet they achieved none. A natural question is to ask why OpenAI would go through with such a PR stunt that risks alienating their customers. These companies are spending tens of billions of dollars a year more than they earn, which helps to explain their thirst for PR stunts and their willingness to take such seemingly inexplicable risks.

Mathematicians now type half-formed ideas into commercial models every day. These sessions are invaluable to an AI company: they provide a road map of our thought process, and reveal which research directions are promising. Until recently, AI-assisted proofs of important mathematical results were considered a pipe dream, and many of us were simply not concerned with data privacy since we never imagined today’s capabilities arriving so quickly.

It is imperative to protect our ideas and not let AI companies become the ultimate gatekeepers of knowledge. In this vein, I would like to see:

  • Collective enterprise agreements with AI companies should become ubiquitous. Many universities already have institutional agreements with AI providers, and these offer far better protections than consumer agreements. Even so, such agreements could be further strengthened by including zero data retention clauses and auditing provisions to ensure that the conditions of the agreements are respected. Many mathematicians, myself included, do their research on consumer subscriptions that those agreements do not cover. We need to make sure all academics work under the protection of such agreements.
  • We need stricter regulatory guardrails on user data. More generally, we need stricter regulations governing how AI companies collect data. Training on user data must be explicitly opt-in rather than opt-out. Finally, deceptive practices, such as absorbing an entire session’s worth of data as a result of a user providing feedback on a single response, must be explicitly banned.
  • We should further invest in open-weight infrastructure, assisting in the development of open-weight models. We cannot assume the interests of Academia and the AI companies are aligned. Academic institutions that control where their models are run can circumvent the fear of having their ideas stolen by trillion dollar corporations. Chess was democratized by engines anyone could run at home. Shared, open infrastructure for mathematics, funded in an independent way, is a lofty goal worth pursuing.
Less reliance on user data benefits both sides: leading to more trust from the academics and the encouragement of new innovative ways to train models.

Recognizing contributions: As Tao put it at the ICM this summer, we are moving from an era of proof scarcity to an era of proof abundance. Our credit system was built for the era of scarcity. Being first to a famous result was a reasonable proxy for depth of understanding, because nobody could get there without understanding a great deal along the way. That proxy no longer holds and so we will need new ways of assigning credit that are not simply correlated with access to resources.

Some concrete suggestions:

  • Reward well written exposition of important results in mathematics.
  • AI disclosures are a mixed bag and there is currently a perverse incentive not to disclose the use of AI. Disclosing AI assistance should not diminish a result and detailed disclosures should become standard.
  • Development of shared tools and resources, as well as contributions to large collaborative projects should earn recognition, mimicking practices in other sciences.
  • Mathematicians should be evaluated on the ideas and methods they developed, not just on whether or not they were first to prove a result.
More generally, we will need to move away from bean counting publications in top journals. Whatever replaces it must still offer transparent ways of evaluating work, rather than relying on reputation and personal connections, which tends to produce closed networks and patronage.

The future of mathematics: Chess did not end in 1997. Mathematics will not end in 2026. I am however convinced that within the next few years it will be unrecognizable. That future will not be shaped by me or my peers. It will be shaped by the next generation.

I am already amazed by what our students and postdocs at NYU are doing with these tools. I suspect that in their hands the line between pure and applied mathematics will blur further, perhaps disappear, and that we will see a richer connection between mathematical proofs and the physical sciences.

For the next generation of mathematicians to flourish, we need protections and control over user data, restraint from AI companies, a lower barrier to entry to the use of frontier-level models, and a new credit system that rewards understanding rather than access. Mathematics has long been said to belong to the young. They will decide what it becomes.

AI Disclaimer: I used LLMs to help edit this post, including suggesting wording for some passages.

Jordan Ellenberg — “You Can See Everything”

I don’t feel like writing a whole dissertation about this but I’ll just say that this is the first time I can remember saying “Oh my God,” out loud, multiple times, while watching a movie in a theater.

Some people have asked if you need to be familiar with the story of Elizabeth Holmes to watch this movie. I don’t think so. I’m not familiar with the Holmes/Theranos story beyond the bare basics. This movie is almost entirely not about that story; or at least that’s how it plays if you don’t know the story.

Terence Tao — A sketch of the proof of non-existence of Siegel zeroes

For a given prime {p}, the Legendre symbol {\left(\frac{D}{p}\right)} is defined as follows: if {D} is a quadratic residue modulo {p}, then {\left(\frac{D}{p}\right) = 1}; if {D} is a quadratic non-residue modulo {p}, then {\left(\frac{D}{p}\right) = -1}; and if {p} divides {D}, then {\left(\frac{D}{p}\right) = 0}.

Let {D} be an integer that is not a perfect square. (One could require {D} to be a fundamental discriminant if desired, although it turns out to be immaterial for the arguments here.) By combining quadratic reciprocity with the prime number theorem in arithmetic progressions, one can show that the Legendre symbol is asymptotically balanced between {+1} and {-1}. For instance, one can show that

\displaystyle  \sum_{p \leq x} \left(\frac{D}{p}\right) \frac{\log p}{p} = o\left(\log x\right)

as {x \rightarrow \infty}, where the sum is over primes {p}; equivalently (by Mertens’ theorem),

\displaystyle  \sum_{p \leq x : \left(\frac{D}{p}\right) = -1} \frac{\log p}{p} = \frac{1}{2} \log x + o\left(\log x \right). \ \ \ \ \ (1)

However, most of the known proofs of this asymptotic are ineffective with regards to the decay of the {o()} error. This is due to the infamous Siegel zero problem, arising from Dirichlet {L}-functions associated to {D} with a zero very close to {s=1}. A well known example comes when {D = -163}, which is a non-residue for all primes {p < 41}; this is closely tied to Euler’s famous observation that {n^2 + n + 41} is prime for all integers {n} with {0 \leq n < 40}, as well as the fact that the ring of integers {{\bf Z}[\sqrt{-163}]} has unique factorization. For further discussion of these topics, see this previous set of lecture notes.

Recently, the Siegel zero problem has been solved in a number of ways. In fact, a stronger “quasi-Riemann hypothesis”, showing that the zeroes of all Dirichlet {L}-functions have real part strictly bounded away from {1}, has been established (with two separate papers giving a bound of {11/12} and {7/8} respectively) as part of a recent release by OpenAI. (In particular, the {o(\log x)} error term in (1) can now be improved to a power saving {O( |D|^{O(1)} x^{-1/8+o(1)})}.) These arguments are analytic in nature, using identities relating the Möbius function to the Fourier coefficients of certain automorphic forms; they are still in the process of being fully digested, and I will not be discussing them further here. However, there was a third paper in the same release that did not establish the quasi-Riemann hypothesis, but instead excluded Siegel zeroes directly. This paper was significantly shorter (nine pages) and proceeded almost entirely via algebraic number theory and the geometry of numbers.

Recently, various digestions and simplifications of the argument have been produced by Banks, by Kerr, and by Green. I would like here to present a sketch of Green’s formulation (with some small notational changes), which I find particularly elegant. The key bound he establishes is

\displaystyle  \sum_{\varepsilon^{-2} \leq p \leq \varepsilon R : \left(\frac{D}{p}\right) = -1} \frac{\log p}{p} \leq \left(1 + O(\varepsilon)\right) \log N \ \ \ \ \ (2)

whenever {\varepsilon > 0} is a small quantity, {N \geq |D|^{1/\varepsilon}} is a suitably large scale, and {R := \lfloor N^{2 - \varepsilon}\rfloor} is a larger scale that is nearly quadratic in {N}. For {\varepsilon} small enough, this improves by a factor of about {\frac{1}{2}} upon the trivial bound

\displaystyle  \sum_{\varepsilon^{-2} \leq p \leq \varepsilon R : \left(\frac{D}{p}\right) = -1} \frac{\log p}{p} \leq \log R + O(1)

coming from Mertens’ theorem; thus (2) is a non-trivial bound on the number of primes {p} at scales up to {\varepsilon R} for which {D} is a quadratic non-residue. By optimizing in {\varepsilon}, this gives the upper bound for (1); in fact with more care one concludes that

\displaystyle  \sum_{p \leq x : \left(\frac{D}{p}\right) = -1} \frac{\log p}{p} \leq \frac{1}{2} \log x + O(\log |D|) + O(\log\log x).

(In fact, some extremely recent preprints of Jacob Pescador and Kevin Barretto have sharpened this bound further, with an upper bound of {\frac{1}{2} \log x + \frac{1}{4} \log |D| + \log\log x + O(1)}.)

One can obtain the full strength of (1) using standard analytic number theory methods (omitted here, but see for instance these previous notes) to rule out Siegel zeroes, which can then in turn be used to upgrade the error term in (1) to a classical shape {\exp(- c \sqrt{\log x})} for some absolute constant {c>0}, assuming {|D| \leq \exp(c \sqrt{\log x})}. Besides this, though, none of the classical analytic number theory methods are utilized in this proof. In retrospect this makes sense, as the infamous “parity problem” blocks such methods from getting results such as (2) without some parity-breaking input: in this case, said input comes from the polynomial method, whereas in the QRH papers, it appears to be some (still poorly understood) automorphic miracle that is breaking the parity barrier.

AI disclosure: a chat session with the new SAIR open math model was used to help understand the preprints. I also benefited from conversations with Ben Green, Alex Pascadi, Lior Silberman, Valentin Blomer, Gergely Harcos, Farrell Brumley, William Banks, and Edgar Assing.

— 1. High-level description of proof —

I will make some minor assumptions and “cheats” to simplify the exposition. Firstly I will restrict to the case when {D} is negative; this makes {{\bf Z}[\sqrt{D}]} have one complex embedding rather than two real embeddings, which allows for a very small simplification to the notation. For extremely minor notational reasons I will also exclude {D=-1}, so that {|D| \geq 2}. I will also pretend at a later point that an arbitrarily chosen high-degree polynomial {P(z_1,z_2)} is irreducible, which is of course not always the case, but allows one to simplify a certain algebraic calculation, the general case of which is handled in Green’s writeup.

The overall strategy is that of the “adelic polynomial method”, which appears in various guises (though usually not with this name) throughout the literature, for instance in the Bombieri–Vaaler paper on Siegel’s lemma (I would be interested in further historical information on the development of the method). We will not actually use any of the machinery of the adeles in this post, though experts will readily see them lying just beneath the surface.

The first observation is just the fundamental theorem of arithmetic, which gives the factorization

\displaystyle  |M| = \prod_p p^{v_p(M)}

for any non-zero integer {M}, where {v_p(M)} is the number of times {p} divides {M}. Taking logarithms, we obtain

\displaystyle  \sum_p v_p(M) \log p = \log |M|. \ \ \ \ \ (3)

So, if one wanted to obtain a bound such as (2), one could try to construct some non-zero integer {M} for which one had some upper bound on the “Archimedean magnitude” of {M}, while also having lower bounds on the valuations {v_p(M)} for primes {p} in the range of (2) for which {D} is a quadratic nonresidue. That is to say, one wants to find an {M} which is not too large, while also being divisible by many powers of such primes {p}, and also non-vanishing.

This quantity {M} will be constructed geometrically, being essentially the covolume of a certain lattice (actually the square of that covolume, to make it an integer). Let {S := \lfloor \varepsilon R \rfloor} be a small multiple of {R}. First let {\Lambda} be the set of polynomials {P(z_1,z_2)} with integer coefficients that are of degree less than {(R,S)} in the two variables {z_1,z_2}, by which we mean that they are of degree less than {R} in the {z_1} variable, and less than {S} in the {z_2} variable. The behavior in {z_1} will be more important for us than that in {z_2}, and this is reflected in the disparity in sizes between the two degrees {R,S}.

Clearly {\Lambda} is a lattice of rank {RS}. We will evaluate this lattice on the {N \times N} grid

\displaystyle  E := \{ (m + n\sqrt{D}, m - n\sqrt{D}): m,n \in {\bf Z}, 0 \leq m, n < N \}.

The idea of evaluating a lattice or vector space of polynomials on various carefully selected sets such as {E} lies at the heart of the polynomial method, with a focus often being made on the extent to which such polynomials can vanish on {E}. In many variants of the polynomial method, one also analyzes the extent to which such polynomials can vanish with multiplicity on {E}; Stepanov’s method (discussed for instance in this previous post) is one well-known example. One of the innovations in Green’s treatment is to also take advantage of multiplicity to achieve the non-trivial bound (2); previous treatments did not do this, and had to work with a (somewhat artificial) extension of {{\bf Z}[\sqrt{D}]}, such as {{\bf Z}[\sqrt{D}, \sqrt{2}]}, in order to get comparably non-trivial bounds.

Specifically, for each polynomial {P} in {\Lambda}, we consider the evaluations

\displaystyle  TP := \left( \partial_{z_1}^j P(z_1, z_2) \right)_{0 \leq j < J; (z_1,z_2) \in E}

of the first {J} horizontal derivatives of {P} at each point of {E}, where the optimal choice of {J} turns out to be {J=S}, though as these two quantities play conceptually different roles we will continue to denote them by different symbols.

The tuple {TP} is an element of {{\bf Z}[\sqrt{D}]^{J \times N^2}}, and so {T\Lambda} is some additive subgroup of {{\bf Z}[\sqrt{D}]^{J \times N^2}}. A key fact is:

Lemma 1 (Injectivity) {T} is injective on {\Lambda}. In other words, if {P} is a non-zero element of {\Lambda}, then {P} cannot vanish to (horizontal) order {J} at every point of {E}.

We will prove this later using the theory of resultants.

Thus {T\Lambda} is a lattice of rank {RS}. To this lattice, we can prescribe a (squared) covolume {M} as follows. Let {v_1,\dots,v_{RS}} be some basis for this lattice, then form the {RS \times RS} Gram matrix

\displaystyle  \left( \langle v_i, v_j \rangle \right)_{1 \leq i,j \leq RS}

where we embed {{\bf Z}[\sqrt{D}]^{N \times N^2}} into {{\bf C}^{N \times N^2} \equiv {\bf R}^{2 \times N \times N^2}} in the usual fashion with the Euclidean inner product for the purpose of defining the (real) inner product. This Gram matrix depends on the choice of basis, but the determinant does not; we then take {M} to be this determinant. Geometrically, one can think of {M} as the square of the volume of a fundamental domain of {T\Lambda}.

Some basic facts about {M}. Firstly, the injectivity in Lemma 1 shows that {M} is non-zero. As all the coefficients of the basis vectors {v_i} lie in the ring {{\bf Z}[\sqrt{D}]}, the inner products {\langle v_i, v_j \rangle} are all integer, and so {M} is also. Hence {M} is a non-zero integer. (It is also positive, although this is irrelevant for us.) In particular, the fundamental theorem of arithmetic gives (3).

It is easy to bound the Archimedean size of {M}:

Lemma 2 (Archimedean bound) We have

\displaystyle  \log |M| \leq (1 + O(\varepsilon) ) R^2 S \log N.

This will be a straightforward application of Hadamard’s inequality, using the obvious monomial basis, we prove this later in the post.

Now for the arithmetic input. Suppose that {p} is an (odd) prime for which {\left(\frac{D}{p}\right) = -1}. From Fermat’s little theorem we have

\displaystyle  D^{\frac{p-1}{2}} = -1 \hbox{ mod } p

and therefore

\displaystyle  \sqrt{D}^p = - \sqrt{D} \hbox{ mod } p {\bf Z}[\sqrt{D}].

From further application of Fermat’s little theorem (and the Frobenius automorphism), this implies that

\displaystyle  (m + n \sqrt{D})^p = m - n \sqrt{D} \hbox{ mod } p {\bf Z}[\sqrt{D}]

for any integers {m,n}. In particular, from a {p}-adic point of view, the grid {E} lies close to the curve

\displaystyle  \{ (z_1,z_2): z_1^p - z_2 = 0 \}.

If the grid {E} happened to lie exactly on this curve, then the lattice {T\Lambda} would degenerate (contradicting Lemma 1) and {M} would now vanish. This of course does not happen; but the fact that {E} is {p}-adically close to the curve will force {M} to be {p}-adically close to zero, or equivalently give a useful lower bound on {v_p(M)}:

Lemma 3 (Non-Archimedean bound) If {\varepsilon^{-2} \leq p \leq \varepsilon R} and {\left(\frac{D}{p}\right) = -1}, then

\displaystyle  v_p(M) \geq (1-O(\varepsilon)) \frac{R^2 S }{p}.

We prove this bound later in the post. Inserting Lemma 2 and Lemma 3 into (3) and cancelling the common factor of {R^2 S}, we obtain (2) as required.

— 2. Injectivity —

Now we establish Lemma 1. From my understanding, these sorts of non-vanishing theorems go back to the work of Masser (and the Kerr preprint explicitly uses Masser’s bounds to obtain an analogue of this lemma), which initially used a fair amount of ring theory, but a more elementary alternate approach based on the interpolating polynomial method was introduced by Laurent, an adaptation of which is used in the OpenAI release. Green’s approach is simpler still, based largely on the theory of resultants to project the (high-order) vanishing of a two-variable polynomial to a (high-order) vanishing of a one-variable polynomial.

As {E} is an {N \times N} grid, a direct application of the Schwartz–Zippel lemma tells us that a non-zero degree {d} polynomial can only vanish on at most {dN} of the points of {E}. This is not directly useful for us because the degree of {P} can be as large as {R+S \asymp N^{2 - O(\varepsilon)}}, and so this does not prevent {P} from vanishing on all of {E}. And indeed, if we replaced {E} by the standard {N \times N} grid

\displaystyle  E' := \{ (m, n): 0 \leq m,n < N \}

then the degree {N} polynomial {\prod_{0 \leq n < N} (z_2-n)} already vanishes on {E'}, as does all of the horizontal derivatives of this polynomial. So to proceed here we have to somehow use the fact that the grid {E} is “skew”; in particular we will take advantage of the fact that the {N^2} second coordinates {m - n \sqrt{D}} of this grid are all distinct, in contrast to the situation with {E}.

Let {P(z_1,z_2)} be a non-zero polynomial of degree less than {(R,S)}. To avoid technicalities we will assume that {P} is irreducible, and not solely a function of {z_2}, so that {\partial_{z_1} P} is not identically zero; the general case is treated in Ben Green’s note.

Suppose that {P} vanishes horizontally to order at least {J} at a point {(z_1^0, z_2^0)}, then by performing a Taylor expansion around that point we can factor {P} as

\displaystyle  P(z_1,z_2) = (z_1 - z_1^0)^J Q(z_1,z_2) + (z_2 - z_2^0) R(z_1,z_2)

for some polynomials {Q,R} of degree less than {(R-J,S)} and {(R,S-1)} respectively. If we take one derivative in the {z_1} direction, then {\partial_{z_1} P(z_1,z_2)} vanishes to order at least {J-1} at the same point, thus

\displaystyle  \partial_{z_1} P(z_1,z_2) = (z_1 - z_1^0)^{J-1} \tilde Q(z_1,z_2) + (z_2 - z_2^0) \tilde R(z_1,z_2)

for some polynomials {Q,R} of degree less than {(R-J-1,S)} and {(R-1,S-1)} respectively.

Since {P} and {\partial_{z_1} P} both vanish to high order at {(z_1^0, z_2^0)}, it is natural to look at the horizontal resultant {\mathrm{Res}_{z_1}(P, \partial_{z_1} P) \in {\bf Z}[z_2]} of these two polynomials (which we now view a {{\bf Z}[z_2]}-valued polynomials of {z_1}), defined as the determinant of the {(R-1) + (R-2)} polynomials

\displaystyle  P, z_1 P, \dots, z_1^{R-2} P, \partial_{z_1} P, z_1 \partial_{z_1} P, \dots, z_1^{R-3} \partial_{z_1} P

each of which we view as vectors of {(R-1) + (R-2)} coefficients in {{\bf Z}[z_2]}. Note that all the polynomials in this list take the form

\displaystyle  (z_1 - z_1^0)^{J-1} Q'(z_1,z_2) + (z_2 - z_2^0) R'(z_1,z_2)

for some polynomials {Q', R'} of degree less than {(2R-J, S)} and {(2R, S)} respectively (here we drop some irrelevant lower order terms). By multilinearity of the determinant, the resultant now splits into a linear combination of various determinants involving {k} expressions of the form {(z_1 - z_1^0)^{J-1} Q'(z_1,z_2)} and {(R-1)-(R-2)-k} expressions of the form {(z_2 - z_2^0) R'(z_1,z_2)}. As {Q'} is of degree less than {2R-J} in the {z_1} variable, any contribtion with {k > 2R-J} must vanish, and so we need to have at least {J-O(1)} factors of the form {(z_2 - z_2^0) R'(z_1,z_2)}. We conclude that the resultant {\mathrm{Res}_{z_1}(P, \partial_{z_1} P)} is divisible by {(z_2 - z_2^0)^{J - O(1)}}.

On the other hand, a straightforward degree count shows that this resultant is a polynomial of {z_2} of degree {O(RS)}. The hypothesis that {P} is irreducible and {\partial_{z_1} \not \equiv 0} implies that the resultant is non-zero. So if {P} vanished to order at least {N} at each of the {N^2} points {(z_1^0, z_2^0)} of {E}, then the resultant would have to be divisible by {N^2} different factors of {(z_2 - z_2^0)^{J - O(1)}} (here we use the fact that the {z_2^0} are all distinct), leading to the inequality

\displaystyle  O(RS) \geq N^2 (J - O(1))

which is false for {\varepsilon} small enough by the choice of {N}, {J}, {R}, and {S}. This proves Lemma 1.

— 3. Archimedean bound —

The Archimedean bound is straightforward. For any basis {v_1,\dots,v_{RS}} of {T\Lambda}, the quantity {M} is simply the square of the {RS}-dimensional parallelepiped with edges {v_1,\dots,v_{RS}}, viewed as elements of {{\bf C}^{J \times N^2} = {\bf R}^{2J \times N^2}}. By the Hadamard’s inequality, we thus have

\displaystyle  |M| \leq \prod_{i=1}^{RS} \| v_i \|^2

(using the usual Euclidean norm), or upon taking logarithms

\displaystyle  \log |M| \leq 2 \sum_{i=1}^{RS} \log \|v_i\|.

Applying the sampling operator {T} to the monomial basis {z_1^i z_2^j}, we thus have

\displaystyle  \log |M| \leq 2 \sum_{0 \leq i < R} \sum_{0 \leq j < S} \log \|T (z_1^i z_2^j) \|.

Each point in the grid {E} is of size {O( N \sqrt{D} ) = O( N^{1+O(\varepsilon)})} by choice of {N}. Every component of {\|z_1^i z_2^j\|} then has size {O( R^J O(N^{1+O(\varepsilon)})^{i+j})}, and so

\displaystyle  \|T (z_1^i z_2^j) \| \ll N^{O(1)} R^J O(N^{1+O(\varepsilon)})^{i+j}

or on taking logs and using the construction of {R}

\displaystyle  \log \|T (z_1^i z_2^j) \| \leq (1 + O(\varepsilon)) (i+j) \log N + O( J \log N ).

Summing the arithmetic series in {i,j} we obtain

\displaystyle  \log |M| \leq (1 + O(\varepsilon)) (R+S) RS \log N + O( R S J \log N ).

By construction we have {R+S = (1+O(\varepsilon)) R} and {J = O(\varepsilon R)}, so Theorem 2 follows.

— 4. Non-Archimedean bound —

Let {p} be a prime with {\varepsilon^{-2} \leq p \leq \varepsilon R} and {\left(\frac{D}{p}\right) = -1}. As discussed in the high-level overview, the polynomial {z_1^p - z_2} takes values in {p {\bf Z}[\sqrt{D}]} on the entire grid {E}. This has the following consequence: any polynomial {P(z_1,z_2)} which is divisible by {(z_1^p-z_2)^k} for some {k} will take values in {p^k {\bf Z}[\sqrt{D}]}. Furthermore, the same is true for any iterated {z_1}-derivative of {P}: note from the chain rule that applying {\partial_{z_1}} to {(z_1^p-z_2)^k} will lower the exponent {k} by {1}, thus removing one factor of {p}, but also produce an additional factor of {p z_1^{p-1}} which restores that missing factor. We conclude that every coefficient of {TP} then lies in {p^k {\bf Z}[\sqrt{D}]}.

To use this, we replace the standard monomial basis {z_1^i z_2^j}, {0 \leq i < R}, {0 \leq j < S} of {\Lambda} with the modified basis

\displaystyle  z_1^{i - p k_{i,j}} (z_1^p - z_2)^{k_{i,j}} z_2^j

for {0 \leq i < R}, {0 \leq j < S}, where

\displaystyle  k_{i,j} := \min ( \lfloor \frac{i}{p} \rfloor, S-1 - j ).

Note that such a basis element still lies in {\Lambda}, and is of the form {z_i^i z_2^j} plus a linear combination of monomials that are lower than this in the lexicographical ordering. So this modified basis remains a basis of {\Lambda}. Applying {T}, we see from the previous discussion that each of the basis elements is divisible by {p^{k_{i,j}}}. Computing the Gram matrix in this basis, we conclude that

\displaystyle  v_p(M) \geq 2 \sum_{0 \leq i < R} \sum_{0 \leq j < S} k_{i,j}.

For {j \leq (1 - \varepsilon) S}, one has {k_{i,j} = (1 + O(\varepsilon)) \frac{i}{p}} by the hypotheses on {p} and the choice of {R,S}. We thus have

\displaystyle  v_p(M) \geq 2 (1 - O(\varepsilon)) S \sum_{0 \leq i < R} \frac{i}{p}

and Theorem 3 then follows by summing the arithmetic series.

Tommaso Dorigo — Understanding Intelligence Across Artificial and Biological Systems

Understanding Intelligence Across Artificial and Biological Systems

 Recently I started a new peer-reviewed journal at the crossroads of Artificial Intelligence and Cognition research. The journal, titled "AI and Brain", is published by Scilight Press, a young publishing firm that contrarily to my initial impressions is very serious and competent.

Tommaso Dorigo
Categories

Scott Aaronson AI Alignment Theory Course: Readings and Rapporteur Reports!

As I announced on this blog a couple weeks ago, I’m teaching a new course this semester at UT Austin, entitled AI Alignment Theory. To call such a course “timely” seems like an understatement; this is the first course I’ve ever taught for which multiple gargantuan developments relevant to the course have happened while I was teaching it.

Since AI alignment is still a field with no standard textbook (although that might be changing), no accepted body of mathematical theory, etc. etc., the way we’ve been running the course is like a humanities discussion seminar, albeit one that happens to be in a CS department and to include technical results from time to time. Basically, in each class session, a student “rapporteur” gives a talk on an AI alignment reading—which include “ancient” readings (from way back in 2016), “modern” readings (from, say, last week), and everything in between—and then we freely discuss and debate whatever was presented, with my own role mostly limited to that of gadfly (occasionally I’ll do a mini-lecture on some technical concept).

Anyway, two weeks ago, I promised a list of the papers and other writings that we’ve been discussing, as well as student “rapporteur reports” on those papers, which cover not only the papers themselves, but the students’ thoughts about the papers and (anonymized) summaries of points raised during our class discussion. People have been bugging me for that ever since.

Since I am to please, here you are, without further ado! I’ll continue to update the list as the semester progresses, so that this post can serve as a central public repository for the course.

  1. AGI Ruin: A List of Lethalities, by Eliezer Yudkowsky (2022). Rapporteur report by Tennyson Bardwell (this is the one that we posted previously).
  2. Concrete Problems in AI Safety, by Amodei, Olah, Steinhardt, Christiano, Schulman, and Mané (2016). Rapporteur report by Daniela Wiepert.
  3. The Alignment Problem from a Deep Learning Perspective, by Ngo, Chan, and Mindermann (many versions but latest is 2025), and Research Priorities for Robust and Beneficial Artificial Intelligence by Russell, Dewey, and Tegmark (2016). Rapporteur report by Oleg Pittman and Jack Holt.
  4. What Happened: OpenAI and HuggingFace, by Zvi Mowshowitz; The Rise and Fall of Agent Civilizations, by Dwarkesh Patel, and the METR report by on the HuggingFace incident, by Greenblatt, Cotra, and Wijk (all 2026). Rapporteur report by Shourjo Aditya Chaudhuri and John Robertson.
  5. We Must Pace the Frontier, by Dario Amodei (2026). Rapporteur report by Dhilan Shah.
  6. The Basic AI Drives, by Stephen Omohundro (2008), and Optimal Policies Tend to Seek Power, by Turner, Smith, Shah, Critch, and Tadepalli (2023). Rapporteur report by Bill Zheng.
  7. Corrigibility, by Soares, Fallenstein, Yudkowsky, and Armstrong (2015). Rapporteur report by Sukrut Chikodikar.
  8. The Off-Switch Game, by Hadfield-Menell, Dragan, Abbeel, and Russell (2017). Rapporteur report by Praneel Seth.
  9. Planting Undetectable Backdoors in Machine Learning Models, by Goldwasser, Kim, Vaikuntanathan, and Zamir (latest version 2024), and Oblivious Defense in ML Models: Backdoor Removal without Detection, by Goldwasser, Shafer, Vafa, and Vaikuntanathan (2025). Rapporteur report by Agrim Jain and Indira Dutta.
  10. Backdoor Defense, Learnability, and Obfuscation by Christiano, Hilton, Lecomte, and Zhu (2024), and Unelicitable Backdoors in Language Models via Cryptographic Transformer Circuits, by Draguns et al. (2024). Rapporteur report by John Dunbar (coming).
  11. Functional Decision Theory: A New Theory of Instrumental Rationality, by Eliezer Yudkowsky and Nate Soares (2018). Rapporteur report by Isaac Noel (coming).
  12. Robust Cooperation In the Prisoner’s Dilemma: Program Equilibrium via Provability Logic, by Barasz, Christiano, Fallenstein, Herreshoff, LaVictoire, and Yudkowsky (latest version 2021). Rapporteur report by Shunan Zheng (coming).
  13. Sleeper Agents: Training Deceptive LLMs that Persist Through Safety Training, by Hubinger et al. (long list of authors) (2024). Rapporteur report by Anthony Wang (coming).
  14. Social Choice Should Guide AI Alignment in Dealing with Diverse Human Feedback, by Conitzer et al. (long list of authors) (2024) and Toward a Theory of Value in AI Alignment, by Ahmed, Birhane, Smart, Kay, Shrishak, and Tobin (2026). Rapporteur report by Priyanka Sadagopan (coming).
  15. Claude’s Constitution, by Amanda Askell, Joe Carlsmith, Chris Olah, Jared Kaplan, Holden Karnofsky, et al. (2026). Rapporteur report by Alan Li (coming).
  16. AI Safety via Debate, by Geoffrey Irving, Paul Christiano, and Dario Amodei (2018). Rapporteur report by Sampoorna Poria (coming).
  17. Scalable AI Safety via Doubly-Efficient Debate, by Jonah Brown-Cohen, Geoffrey Irving, and Georgios Piliouras (2023). Rapporteur report by Aarushi Lakhi (coming).
  18. AI as Normal Technology, by Arvind Narayanan and Sayash Kapoor (2025). Rapporteur report by Weixi Chen (coming).
  19. On the Dangers of Stochastic Parrots, by Emily Bender, Timnit Gebru, Angelina McMillan-Major and Shmargaret Shmitchell (2021). Rapporteur report by George Tsoukalas (coming).

(More readings TBD, until the semester ends!)

Thanks to my TA, Lin Lin Lee, for her help in getting all of this together.

Update: I welcome elevated discussion of these papers and rapporteur reports in the comment section; some of the students might chime in too! Because of the connection to an academic class, though, in this post I’ll be especially ruthless in keeping out nonconstructive or off-topic comments.

October 19, 2026

Jacques Distler AI Meets Nonabelian Hodge

As many of you know, I have spent far too much time thinking about families of Hitchin systems over the moduli space ℳ g,n\mathcal{M}_{g,n} of (punctured) Riemann surfaces, C g,nC_{g,n}. In my defense, the Coulomb branch geometry of a 4d 𝒩=2\mathcal{N}=2 theory is encoded in the data of a complex integrable system. For class-S, that’s a Hitchin system and the “conformal manifold” of a family of 𝒩=2\mathcal{N}=2 SCFTs is the aforementioned moduli space. So it’s quite natural to consider the family of Hitchin systems as we vary the exactly-marginal parameters of the SCFT.

A striking feature of Hitchin’s integrable system is that it’s actually hyperKähler; it has a whole ℂℙ 1\mathbb{CP}^1 worth of complex structures. We always work in the complex structure where it has the interpretation as the moduli space of Higgs bundles. This is the physically-interesting case where the base of the Hitchin system (the space of “action variables” of the integrable system) is the Coulomb branch of the 4d theory.

One of the main points of our work is that the bundle of Hitchin bases has a natural extension to the Deligne-Mumford compactification ℳ¯ g,n\overline{\mathcal{M}}_{g,n}, and that extension has an interesting interpretation in the physics.

In another complex structure, Hitchin’s system has the interpretation as a character variety: the space of homomorphisms π 1(C)→G ℂ\pi_1(C)\to G_{\mathbb{C}} up to overall conjugation.

The map from semi-stable parabolic Higgs bundles (E,Φ)(E,\Phi) to the irreducible character variety for G ℂ=SL NG_{\mathbb{C}}=SL_N is called the Nonabelian Hodge Correspondence (NAH). See Simpson’s paper for more details of the correspondence. We’ll be interested in the strongly-parabolic case, where the residues of Φ\Phi are nilpotent.

We had some interesting conjectures about NAH in Appendix B of our first paper. So you can imagine that I was quite excited to see a recent paper which claims to construct families of character varieties over ℳ g,n\mathcal{M}_{g,n} and examines how they behave as the curve C g,nC_{g,n} degenerates.

Unfortunately, they start off with a completely-wrong interpretation — they want the gauge group that becomes weakly-coupled in the nodal limit to be a subgroup of the centralizer of the monodromy around the pinching cycle — and then try to reverse-engineer a family that achieves that. The opposite is what’s actually true. To take the extreme case, when the gauge group associated to some cycle (note that we can always associate a gauge group to some cycle; it only becomes weakly-coupled when that cycle pinches) is the full SU(N)SU(N), then the monodromy around that cycle is regular semi-simple (so its centralizer is abelian).

Rather than try to explicate where they went wrong, let me instead work through an example: the “Argyres-Seiberg” example of section 6.1 of their paper.

This is the 4-punctured sphere for SL 3SL_3, with 2 simple and 2 full punctures. On the Higgs bundle side, the Higgs field has simple poles at p 1,p 2p_1,p_2 with residues in the minimal nilpotent orbit and simple poles at p 3,p 4p_3,p_4 with residues in the regular nilpotent orbit.

On the character variety side, we have 4 monodromies {M 1,M 2,M 3,M 4∈SL N|M 1M 2M 3M 4=I} \{M_1,M_2,M_3,M_4\in SL_N | M_1M_2M_3M_4=I\} up to overall conjugation. Under NAH, the conjugacy classes of the M iM_i are determined by the parabolic weights that we assign on the Higgs bundle side.

Specifically, E| pE|_{p} has a filtration

(1)E| p=F l⊃F l−1⊃F l−2⊃…⊃F 1⊃0E|_p = F_l \supset F_{l-1} \supset F_{l-2} \supset \dots \supset F_1\supset 0

where F j=ker(Res(Φ) j)F_j = \ker(Res(\Phi)^j). We assign a set of real numbers α j∈[−1/2,1/2)\alpha_j\in[-1/2,1/2) which sum to 0 and such that the multiplicity of α j\alpha_j is dim(F j/F j−1)\dim(F_j/F_{j-1}) and α j<α j−1\alpha_j\lt \alpha_{j-1}. On the character variety side, the conjugacy class of MM is [M]=exp(−2πidiag(α 1,…,α l))[M]=exp\bigl(-2\pi i\; diag(\alpha_1,\dots,\alpha_l)\bigr). A nilpotent BB that strictly lowers the flag (1) (i.e. such that B(F j)⊂F j−1B(F_j)\subset F_{j-1}) is generically an element of OO, the nilpotent orbit where the residue of Φ\Phi lies. The induced map on Gr j=F j/F j−1Gr_{j}=F_j/F_{j-1} vanishes, so MM is indeed semi-simple.

In our example, E| p 3,4E|_{p_{3,4}} have a full flag, E| p=F 3⊃F 2⊃F 1⊃0 E|_p= F_3\supset F_2\supset F_1\supset 0 so the conjugacy classes of M 3,4M_{3,4} have the form [M]=exp(−2πidiag(α 1,α 2,−α 1−α 2))[M]=exp\bigl(-2\pi i\; diag(\alpha_1,\alpha_2,-\alpha_1-\alpha_2)\bigr). E| p 1,2E|_{p_{1,2}} has the filtration E| p⊃F⊃0 E|_p \supset F \supset 0 So [M]=exp(−2πidiag(α,α,−2α))[M] =exp\bigl(-2\pi i\; diag(\alpha,\alpha,-2\alpha)) and FF is either a line or a plane, depending on the sign of α\alpha.

The character variety in our example is 4 complex-dimensional and I will describe it in an excruciating degree of explicitness.

Warmup

Let’s warm up by considering the character variety for the 3-punctured sphere with 3 full punctures. That’s 2-dimensional and it can be described concretely as follows.

Let A=M 3A=M_3, B=M 4B=M_4 and let CC be the regular semi-simple elements of SL 3SL_3 satisfying ABC=IA B C =I. Let

(2)α =Tr(A), α˜ =Tr(A −1) β =Tr(B), β˜ =Tr(B −1) γ =Tr(C), γ˜ =Tr(C −1) \begin{aligned} \alpha &= Tr(A),\qquad&\tilde{\alpha}&=Tr(A^{-1})\\ \beta &= Tr(B),\qquad&\tilde{\beta}&=Tr(B^{-1})\\ \gamma &= Tr(C),\qquad&\tilde{\gamma}&=Tr(C^{-1})\\ \end{aligned}

Of course, when the Higgs field residues are nilpotent, we have

(3)α˜=α¯,β˜=β¯,γ˜=γ¯ \tilde{\alpha}=\overline{\alpha},\quad \tilde{\beta}=\overline{\beta},\quad \tilde{\gamma}=\overline{\gamma}

But, with malice aforethought, let’s not make that identification just yet.

By a result of Lawton, the character variety is an affine cubic surface whose coefficients are certain polynomials in α,α˜,β,β˜,γ,γ˜\alpha,\tilde{\alpha},\beta,\tilde{\beta},\gamma,\tilde{\gamma}.

Let X=tr(AB −1)−αβ˜,Y=tr(A −1B)−α˜β,Z=tr(ABA −1B −1). X=\mathrm{tr}(A B^{-1})-\alpha\tilde{\beta},\qquad Y=\mathrm{tr}(A^{-1}B)-\tilde{\alpha}\beta,\qquad Z=\mathrm{tr}(A B A^{-1}B^{-1}). These satisfy the cubic equation

(4)S(α,α˜,β,β˜,γ,γ˜)≔{X 3+Y 3+Z 2−XYZ+aX 2+bY 2+eXY+κZ+fX+gY+h=0}⊂ℂ 3S(\alpha,\tilde{\alpha},\beta,\tilde{\beta},\gamma,\tilde{\gamma})\coloneqq\{X^3+Y^3+Z^2-X Y Z + a\,X^2 + b\,Y^2 + e\,X Y + \kappa\, Z + f\,X + g\,Y + h = 0\}\subset \mathbb{C}^3

where the coefficients are a =αβ˜+βγ˜+γα˜ b =α˜β+β˜γ+γ˜α e =αα˜+ββ˜+γγ˜−6 κ =3+αβγ+α˜β˜γ˜−αα˜−ββ˜−γγ˜ f =α 2β+β 2γ+γ 2α+α˜β˜ 2+β˜γ˜ 2+γ˜α˜ 2+αα˜β˜γ+ββ˜γ˜α+γγ˜α˜β−3(α˜β+β˜γ+γ˜α) g =α˜ 2β˜+β˜ 2γ˜+γ˜ 2α˜+αβ 2+βγ 2+γα 2+αα˜βγ˜+ββ˜γα˜+γγ˜αβ˜−3(αβ˜+βγ˜+γα˜) \begin{aligned} a&=\alpha\tilde\beta+\beta\tilde\gamma+\gamma\tilde\alpha\\ b&=\tilde\alpha\beta+\tilde\beta\gamma+\tilde\gamma\alpha\\ e&=\alpha\tilde\alpha+\beta\tilde\beta+\gamma\tilde\gamma-6\\ \kappa&=3+\alpha\beta\gamma+\tilde\alpha\tilde\beta\tilde\gamma-\alpha\tilde\alpha-\beta\tilde\beta-\gamma\tilde\gamma\\ f&= \alpha^2\beta+\beta^2\gamma+\gamma^2\alpha+\tilde\alpha\tilde\beta^2+\tilde\beta\tilde\gamma^2+\tilde\gamma\tilde\alpha^2 + \alpha\tilde\alpha\tilde\beta\gamma+\beta\tilde\beta\tilde\gamma\alpha+\gamma\tilde\gamma\tilde\alpha\beta - 3(\tilde\alpha\beta+\tilde\beta\gamma+\tilde\gamma\alpha)\\ g&= \tilde\alpha^2\tilde\beta+\tilde\beta^2\tilde\gamma+\tilde\gamma^2\tilde\alpha+\alpha\beta^2+\beta\gamma^2+ \gamma\alpha^2+\alpha\tilde\alpha\beta\tilde\gamma+\beta\tilde\beta\gamma\tilde\alpha+\gamma\tilde\gamma\alpha\tilde\beta -3(\alpha\tilde\beta+\beta\tilde\gamma+\gamma\tilde\alpha) \end{aligned} and finally h= α 3+α˜ 3+β 3+β˜ 3+γ 3+γ˜ 3+9 +αβ˜ 2γ˜ 2+α˜β 2γ 2+βγ˜ 2α˜ 2+β˜γ 2α 2+γα˜ 2β˜ 2+γ˜α 2β 2 −2(α 2β˜γ˜+α˜ 2βγ+β 2γ˜α˜+β˜ 2γα+γ 2α˜β˜+γ˜ 2αβ) +αα˜ββ˜γγ˜+αα˜ββ˜+ββ˜γγ˜+γγ˜αα˜ +3(αβγ+α˜β˜γ˜)−6(αα˜+ββ˜+γγ˜). \begin{aligned} h ={}& \alpha^3+\tilde\alpha^3+\beta^3+\tilde\beta^3+\gamma^3+\tilde\gamma^3+9 \\ &+\alpha\tilde\beta^2\tilde\gamma^2+\tilde\alpha\beta^2\gamma^2 +\beta\tilde\gamma^2\tilde\alpha^2+\tilde\beta\gamma^2\alpha^2 +\gamma\tilde\alpha^2\tilde\beta^2+\tilde\gamma\alpha^2\beta^2 \\ &-2\bigl( \alpha^2\tilde\beta\tilde\gamma+\tilde\alpha^2\beta\gamma +\beta^2\tilde\gamma\tilde\alpha+\tilde\beta^2\gamma\alpha +\gamma^2\tilde\alpha\tilde\beta+\tilde\gamma^2\alpha\beta \bigr) \\ &+\alpha\tilde\alpha\beta\tilde\beta\gamma\tilde\gamma+\alpha\tilde\alpha\beta\tilde\beta+\beta\tilde\beta\gamma\tilde\gamma+\gamma\tilde\gamma\alpha\tilde\alpha \\ &+3(\alpha\beta\gamma+\tilde\alpha\tilde\beta\tilde\gamma)-6(\alpha\tilde\alpha+\beta\tilde\beta+\gamma\tilde\gamma). \end{aligned}

Since (4) is quadratic in ZZ, this cubic surface is a branched double-cover of the XX-YY plane. Away from the discriminant locus, D={0=(XY−κ) 2−4(X 3+Y 3+aX 2+bY 2+eXY+fX+gY+h)} D=\{0=(X Y-\kappa)^2-4(X^3+Y^3+a X^2 + b Y^2 + e X Y + f X + g Y +h)\} X,YX,Y are good local coordinates.

Now let’s consider the 4-punctured sphere with 4 full punctures. We can set A′=M 1A'=M_1, B′=M 2B'=M_2 and C′=(M 1M 2) −1=M 3M 4=C −1C'=(M_1 M_2)^{-1}=M_3M_4=C^{-1} is regular semi-simple. We’ll define Fenchel-Nielsen-like coordinates: t=tr(C),t˜=tr(C −1) t=\mathrm{tr}(C),\quad \tilde{t}= \mathrm{tr}(C^{-1}) are the “lengths” and Θ∈Z(C)=T/ℤ 3≃(ℂ *×ℂ *) \Theta\in Z(C)= T/\mathbb{Z}_3\simeq (\mathbb{C}^\ast\times\mathbb{C}^\ast) are the “twists”. Here, we quotiented the maximal torus T⊂SL 3T\subset SL_3 by the ℤ 3\mathbb{Z}_3 center of SL 3SL_3, whose conjugation action is trivial.

The character variety is a (ℂ *×ℂ *)(\mathbb{C}^\ast\times\mathbb{C}^\ast)-fibration (with fiber Θ\Theta) over 𝒳\mathcal{X}, the fiber product of two copies of the affine cubic surface: 𝒳=S L× ℂ 2S R \mathcal{X} = S_L \times_{\mathbb{C}^2} S_R with S L ≔S(α′,α¯′,β′,β¯′,t˜,t) S R ≔S(α,α¯,β,β¯,t,t˜) \begin{aligned} S_L&\coloneqq S(\alpha',\overline{\alpha}',\beta',\overline{\beta}',\tilde{t},t)\\ S_R&\coloneqq S(\alpha,\overline{\alpha},\beta,\overline{\beta},t,\tilde{t}) \end{aligned}

Dehn Twists

The definition of the character variety involved a choice of basis for π 1\pi_1 of the punctured Riemann surface. Imagine cutting the 4-punctured sphere along a circle surrounding p 1,p 2p_1,p_2, rotating by 2π2\pi and gluing back together. This acts on the monodromies (the image of π 1(C 0,4)→SL 3\pi_1(C_{0,4})\to SL_3) as (M 1,M 2,M 3,M 4)→(CM 1C −1,CM 2C −1,M 3,M 4) (M_1,M_2,M_3,M_4)\to (C M_1 C^{-1},C M_2 C^{-1}, M_3, M_4) where, again, C≔M 1M 2C\coloneqq M_1 M_2.

Explicitly, this does not act on 𝒳\mathcal{X}, but it does act on the twists Θ\Theta. Let c 1,c 2,c 3c_1,c_2,c_3, with c 1c 2c 3=1c_1c_2c_3=1 be the eigenvalues of CC. In the basis where CC is diagonalized, a point in TT is a diagonal matrix diag(t 1,t 2,t 3)\mathrm{diag}(t_1,t_2,t_3) with t 1t 2t 3=1t_1t_2t_3=1. Explicit fiber coordinates (points in T/ℤ 3T/\mathbb{Z}_3) are the invariant combinations Θ=(t 1/t 2,t 2/t 3)\Theta=(t_1/t_2,t_2/t_3). The Dehn twist acts as

(5)(Θ 1,Θ 2)→(c 1/c 2Θ 1,c 2/c 3Θ 2) (\Theta_1,\Theta_2)\to (c_1/c_2\; \Theta_1, c_2/c_3\; \Theta_2)

Argyres-Seiberg

Finally, let’s return to the case of interest: where the Higgs-field residues at p 1p_1, p 2p_2 are in the minimal (rather than the regular) nilpotent orbit.

As we saw above, the parabolic weights at p 1p_1, p 2p_2 are (α i,α i,−2α i)(\alpha_i,\alpha_i,-2\alpha_i), which give flags of the form ℂ 3⊃F⊃0\mathbb{C}^3\supset F \supset 0, with FF a plane or a line.

We can write the monodromies at p 1p_1,p 2p_2 in the following form

(6)M i=λ i(I+x iy i t),1+y i tx i=λ i −3,λ i≔exp(−2πiα i) M_i = \lambda_i(I+x_i y_i^t),\qquad 1+y_i^t x_i = \lambda_i^{-3},\qquad\lambda_i\coloneqq exp(-2\pi i\alpha_i)

with x i,y i∈ℂ 3x_i,y_i\in\mathbb{C}^3. As a consequence one of the eigenvalues of C=M 1M 2C=M_1M_2 is pinned to be ν=λ 1λ 2\nu=\lambda_1\lambda_2. Let ss and s′=1/(νs)s'=1/(\nu s) be the remaining eigenvalues of CC. Then the Fenchel-Nielsen length coordinates t=tr(C)t=\mathrm{tr}(C) and t˜=tr(C −1)\tilde{t}=\mathrm{tr}(C^{-1}) are no longer independent. Rather t˜=νt+ν −1−ν 2 \tilde{t} = \nu t + \nu^{-1} -\nu^2

Similarly, there’s just a single twist coordinate. To construct it, let L=y 1 ⊥∩y 2 ⊥L = y_1^\perp\cap y_2^\perp and W=span(x 1,x 2)W=span(x_1,x_2). M iM_i acts on LL as λ i\lambda_i and M ix j∈WM_i x_j\in W. So CC acts as ν\nu on LL and acts with eigenvalues s,s′s,s' on WW. Generically the 2×22\times 2 block is irreducible, so the stabilizer of the pair is T L={aI L⊕bI W|ab 2=1} T_L = \{ a I_L \oplus b I_W | a b^2=1\} The twist θ∈T/T L≃ℂ *\theta\in T/T_L \simeq \mathbb{C}^*. The character variety is now 4-dimensional, given by t,θt,\theta and u∈S(α,α¯,β,β¯,t,νt+ν −1−ν 2)u\in S(\alpha,\overline{\alpha},\beta,\overline{\beta},t,\nu t + \nu^{-1} -\nu^2).

As before, a Dehn twist around the circle surrounding p 1p_1,p 2p_2 acts only on the twist parameter, taking θ→(s/s′)θ=(νs 2)θ\theta\to (s/s')\theta = (\nu s^2)\theta.

I want to emphasize that in both cases, discussed above, the monodromy around the circle surrounding p 1,p 2p_1,p_2 was regular semi-simple (in contrast to what they wanted). What differs in the Argyres-Seiberg case is that one of the eigenvalues of that monodromy is fixed.

The other takeaway is that the action of Dehn twists (which generate the Mapping Class Group) is very transparent once we introduce the Fenchel-Nielsen-like coordinates associated to a compatible pants-decomposition of the curve: the character variety has the structure of an algebraic torus fibration over some base, and Dehn twists act by translations along the fibers.


Generalizations

The Argyres-Seiberg example (2 minimal and 2 regular Hitchin nilpotents) generalizes straightforwardly to SL NSL_N. C=M 1M 2C=M_1M_2 is generically still semi-simple, but no longer regular semi-simple. The monodromies at p 1,2p_{1,2} can be parametrized as M i=λ i(I+x iy i t),1+y i tx i=λ i −N,x i,y i∈ℂ N M_i =\lambda_i(I+x_i y^t_i),\qquad 1+y^t_i x_i=\lambda_i^{-N},\qquad x_i,y_i\in \mathbb{C}^N Let ν=λ 1λ 2\nu=\lambda_1\lambda_2, F=y 1 ⊥∩y 2 ⊥F=y_1^\perp\cap y_2^\perp and W=span(x 1,x 2)W=\mathrm{span}(x_1,x_2). We have dim(F)=N−2\mathrm{dim}(F)=N-2, dim(W)=2\mathrm{dim}(W)=2 and CC acts as νI\nu I on FF and acts with eigenvalues s,s′s,s' (obeying ν N−2ss′=1\nu^{N-2}s s'=1) on WW. The fixture on the right contributes the 2(N−2)2(N-2)-dimension character variety corresponding to the 3-punctured sphere with nilpotents [3,1 N−3],[N],[N][3,1^{N-3}],[N],[N] and there’s one pair of Fenchel-Nielsen coordinates, t=tr(C)t=\mathrm{tr}(C) and θ=d s/d s′\theta=d_s/d_s'. In the language of our paper, pinching the sphere along the circle surround p 1,p 2p_1,p_2 yields ([3,1 N−3],SU(2))([3,1^{N-3}],SU(2)) as the “nilpotent at the node.”

Maybe one more example will give the flavour of the general story. Consider two punctures with residues in the nilpotent orbit [2 n][2^n] of 𝔰𝔩 2n\mathfrak{sl}_{2n}. The conjugacy classes of the corresponding monodromies are [M i]=exp(−2πidiag(α i,…,α i⏟n,−α i,−α i⏟n)) [M_i] = \mathrm{exp}(-2\pi i\;\mathrm{diag}(\underset{n}{\underbrace{\alpha_i,\dots,\alpha_i}},\underset{n}{\underbrace{-\alpha_i,-\alpha_i}})) We can write M i=λ i −1(I−P i)+λ iP i M_i = \lambda_i^{-1}(I-P_i) + \lambda_i P_i where P iP_i is a rank-nn idempotent. The algebra generated by a pair of idempotents has an irreducible representation of dimension at-most 2, so ℂ 2n≃V 1⊕…⊕V n\mathbb{C}^{2n}\simeq V_{1}\oplus\dots\oplus V_{n}, where the V jV_{j} are 2-dimensional spaces on each of which P 1,P 2P_1,P_2 act as rank-1 idempotents. So C=M 1M 2∈SL 2×SL 2×…×SL 2⊂SL 2nC = M_1M_2\in SL_2\times SL_2\times\dots \times SL_2\subset SL_{2n}. CC has eigenvalues x j,x j −1x_j,x_j^{-1} on V jV_{j}. The stabilizer of the pair M 1,2M_{1,2} is T L={diag(a 1,a 1,…,a n,a n)|a 1 2a 2 2…a n 2=1} T_L =\{\mathrm{diag}(a_1,a_1,\dots,a_n,a_n)|a_1^2a_2^2\dots a_n^2=1\} The nn Fenchel-Nielsen length coordinates are t 1=tr V 1(C)=x 1+x 1 −1,…,t n=tr V n(C)=x n+x n −1 t_1= \mathrm{tr}_{V_1}(C)= x_1+x_1^{-1},\quad\dots\quad,t_n= \mathrm{tr}_{V_n}(C)= x_n+x_n^{-1} and the nn twist coordinates Θ∈T/T L≃(ℂ *) n \Theta\in T/T_L\simeq (\mathbb{C}^*)^n The Weyl group for [C]=diag(x 1,x 1 −1,x 2,x 2 −1,…,x n,x n −1) [C]= \mathrm{diag}(x_1,x_1^{-1},x_2,x_2^{-1},\dots,x_n,x_n^{-1}) is W=S n⋉ℤ 2 nW=S_n\ltimes \mathbb{Z}_2^n, which is the Weyl group of the Sp(n)Sp(n) gauge group on the neck. In the language of our paper, the nodal degeneration when two [2 n][2^n] punctures collide yields 4n4n free hypermultiplets transforming as the 2(2n)2(\boldsymbol{2n}) and the nilpotent-at-the-node is ([2n],Sp(n))([2n],Sp(n)).

Special Loci

Throughout, I’ve been describing the behaviour at a generic point of the character variety. The monodromies we found were semi-simple. There are special loci where the behaviour is more complicated.

Consider again the collision of 2 simple punctures (the Argyres-Seiberg example above). When t≔tr(C)=(N−2)ν±2ν −(N−2)/2≕t ±t\coloneqq \mathrm{tr}(C)= (N-2)\nu \pm 2\nu^{-(N-2)/2}\eqqcolon t_\pm, then s=s′=±ν −(N−2)/2s=s'=\pm\nu^{-(N-2)/2}. On that locus, C=M 1M 2C=M_1M_2 develops a nontrivial unipotent part: [C]=diag(ν,…ν⏟N−2,J 2(s)) [C]=\mathrm{diag}(\underset{N-2}{\underbrace{\nu,\dots\nu}},J_2(s)) Z(C)Z(C) is no longer reductive, so the twist coordinate θ\theta is no longer an element of ℂ *\mathbb{C}^*. Now it’s a translation θ∼(1 τ 0 1)\theta\sim\left(\begin{smallmatrix} 1&\tau\\0&1\end{smallmatrix}\right) and Dehn-twists act on it by translating τ\tau.

Circling this divisor (t=t *t=t_\ast) in the character variety takes the twist coordinate θ→θ −1\theta\to\theta^{-1}, a Weyl reflection. So the twist coordinate(s) are only good local coordinates on the character variety.

A good local model near this divisor is as follows. Let C WC_W denote the 2×22\times 2 matrix which is CC restricted to WW. Set σ=12tr(C W),ϵ=14(t−t +)(t−t −) \sigma=\tfrac{1}{2}\mathrm{tr}(C_W),\qquad \epsilon =\tfrac{1}{4} (t-t_+)(t-t_-) We can decompose C W=σI+T,T 2=ϵI C_W = \sigma I + T, \qquad T^2=\epsilon I The twists take values in Z(C W)/ℂ *={aI+bT} ×/ℂ *,i.e.{[a:b]∈ℙ 1|a 2−ϵb 2≠0} Z(C_W)/\mathbb{C}^\ast = \{a I+b T\}^\times/\mathbb{C}^\ast,\quad \text{i.e.}\; \{[a:b]\in \mathbb{P}^1|a^2-\epsilon b^2\neq 0\} Dehn twists act on the homogeneous coordinates of the ℙ 1\mathbb{P}^1 as [a:b]↦[σa+ϵb:a+σb][a:b]\mapsto [\sigma a+\epsilon b: a+\sigma b].

Similar remarks apply whenever any of the free eigenvalues of CC are tuned to coincide. Along the corresponding divisor, CC develops a unipotent part (C=C ssC uC=C_{\mathrm{ss}}C_{\mathrm{u}} with C ssC u=C uC ssC_{\mathrm{ss}}C_{\mathrm{u}}=C_{\mathrm{u}}C_{\mathrm{ss}}). Circling the divisor, the twist coordinates undergo a Weyl reflection.

Scott Aaronson Podcasts about the Topic

“The Topic” being, of course, the Mathocalypse, except sometimes with AI alignment and even quantum computing and complexity theory and other stuff thrown in.

With Ryan Peterman:

Notably, near the end of the above podcast, you can watch my live reaction to the news that an Anthropic model found algorithms for the 3SUM and the All-Pairs-Shortest-Path problems beating records that stood for generations—news that hadn’t yet reached me when I woke up and logged in. (If you don’t feel like watching, my reaction is basically: “uh, wow … if I hadn’t been so overstuffed with delicacies right now from history’s biggest math breakthrough buffet, I’d surely be giving this one the individual amazement that it deserves…”)

And here’s with “Modern CTO”, on a similar set of topics:

Oh, and a third one: MTS podcast with Theo Jaffee.

Enjoy, and thanks to the hosts of these podcasts!


Update (Oct. 19): There’s been a rapid-fire recent sequence of AI-assisted improvements to my 2016 result with Adam Yedidia, showing that the 8000th Busy Beaver number eludes the axioms of set theory. I haven’t even kept track of all of them, but the very latest, by friend-of-the-blog Elliot Glazer, shows that the value of BB(230) is independent of ZFC (see here for explanation).

John Preskill — Even sampling from a quantum spin glass may not require a quantum computer (a video abstract, for a change)

First, why a video?

I am part of a generation that was raised on a nourishing diet of science communication videos on YouTube. The likes of MinutePhysics, Veritasium, VSauce, Crash Course, TED-Ed, Physics Girl, 3Blue1Brown — you name it, these channels were my childhood. Had they not existed, I may very well have never considered pursuing a physics PhD here at Caltech.

But you probably already knew about the power of science communication in its ability to inspire the next generation. I am here to convince you that science communication just became a whole lot more important.

Earlier this month, Terence Tao gave a talk at Caltech about the growing use of AI in mathematics. In light of OpenAI’s recent release of hundreds of AI-generated mathematical manuscripts, he argued that our community has transitioned from a long era of proof scarcity to one of proof abundance. As a result, problem-solving may no longer be the central challenge in mathematics and theoretical physics that it once was. What surprised me most, though, was Terence’s claim that problem-solving was never the central goal in the first place. It was only ever a proxy for the actual goal of these disciplines: to elevate human understanding.

I do not think we have fully internalized this maxim as a community yet. The arXiv is seeing a flood of AI-generated submissions that claim to solve problems but offer very little insight. So how do we encourage human understanding?

Perhaps a video recording is one good way. Flagship conferences like STOC 2027 have begun requiring video recordings as part of their submission process to prioritize effective scientific communication and filter out low-insight AI-generated submissions. On one level, requiring authors to explain their work over video establishes a standard that scientific research should remain intelligible to others.

But on another level, a video recording captures something of the humanness of the act of understanding itself. When I understand something, I feel like I can taste it, almost as if it were a sensory experience. I then feel empowered, as if I have been given a new tool to use, and subsequently feel an excitement to share that insight with other human beings. In other words, understanding is an embodied phenomenon. And what better way to embody your work than to stand before a camera and explain it?

Science communication is no longer just about communicating science to people outside the field. It is increasingly about ensuring that the scientific progress we make be accompanied by a corresponding growth in human understanding. So go out there and record yourself geeking out!

About the work

Quantum spin glasses are, in some ways, very quantum systems. Their Hamiltonians contain many non-commuting terms, and their low-energy states can be far from simple product states that are easy to represent classically.

One might therefore expect these systems to be difficult to simulate on a classical computer. Yet, in our recent work, we show strong evidence that there is no exponential quantum advantage for sampling from the thermal states of one such quantum spin glass model.

The key is to reduce sampling to estimating certain quantities related to the model called tilted means, which we expect to be classically easy. I say expect because our results rely on a conjecture from spin-glass physics that is widely believed to hold true, but has yet to be rigorously proven with existing mathematical tools. Such assumptions are quite common in the spin-glass community.

The video above focuses more on why we wanted to study sampling than on how we actually solved the problem in order to make it accessible to a general audience. For those curious, our approach is based on stochastic localization, a sampling technique closely related to diffusion models. More technical details can be found in our arXiv preprint.

Tim Gowers — How worried should we be about extinction risk from AI?

A little over two months ago, Jacob Tsimerman surprised a lot of people by announcing, immediately after he had received a Fields Medal, that he would be giving up mathematical research and “pivoting to AI safety”. He had two reasons for this: that he did not see much future for the kind of research in mathematics that he liked doing, and that he was very worried about the dangers of AI, and in particular of the risk that it could kill us all, or x-risk as it is often known. (In this post I’ll use x-risk to refer to the extinction risk from AI rather than to extinction risk in general. I’ll also refer to “the probability of x-risk” when what I actually mean is the probability of extinction by AI.) Then in early September, he announced that he was setting up the Mathematical AI Safety Institute, or MAISI. He asked me if I would be prepared to be on the scientific advisory panel for this, and I agreed to do so, not because I am an expert, or because I felt as concerned as he did about x-risk, but because I don’t really know how much I ought to be worried about it. Given that, and given that the stakes are so high, I would like as many people as possible to be thinking seriously about it, and I agree with Jacob that mathematicians have the sort of training that makes them well suited to contribute. Jacob is the first to admit that something like an international treaty to slow down AI development is likely to have a far bigger impact on AI safety, especially in the short term, than mathematicians obtaining a better theoretical foundation for talking about it, but his view is that we need all hands on deck. If mathematicians can reduce the probability of x-risk by 0.1%, then surely that’s worth doing: the expected number of lives saved is over eight million.

Until recently, I have always found that my anxiety of choice was climate change rather than x-risk, but I was aware that there were a lot of very intelligent people who disagreed with me, and also aware that I had thought much less about x-risk than about climate change. So when I agreed to be on the scientific advisory panel, I also decided that that was the moment that I should think a bit harder about x-risk. Part of me had been actively resisting doing so, because I was worried that it would force me to face up to moral responsibilities that I would rather avoid: for example, if I came to believe that there was a 30% chance that AI would kill us all within five years, which in some circles is not an extreme position, would I be able to look my one-and-a-half-year-old grandson in the face if I wasn’t making a big effort to reduce that risk? I remember having a similar attitude a long time ago to reading Peter Singer’s book Animal Liberation after being told that you can’t read it and not become a vegetarian. I never did read it, and carried on eating meat, feeling only slightly uncomfortable about it. Eventually I did reduce my meat intake substantially, but that was because of my worries about climate change, though now that I have done that I find myself caring more about the animal-welfare aspect as well. (There is also a strange connection between animal welfare and x-risk, in that the nicer we are to animals, the easier it is to hope — not necessarily realistically — that a superhumanly intelligent AI might be nice to us.)

Anyhow, I’ve got past that phase now, and have started thinking about x-risk, reading up on the subject and trying to evaluate the arguments I read. My plan for this post is to explain where I’ve reached in that thought process, and possibly to clarify my thoughts as I do so. If you have got further than me, or are more expert than I am about x-risk and AI, which is not hard, then the post is not aimed at you. It’s aimed more at someone who is roughly at the stage that I was at a little while ago, in the hope that I might nudge a few people a little further towards taking the problem seriously. I will emphatically not be trying to persuade anybody that a particular position about x-risk is the right one — I am far too uncertain about it to be able to do that. But with all big issues like this, there are several layers to the arguments. The bottom layer consists of the arguments that jump to mind when you first start thinking about the issue. The next layer is common rejoinders to those arguments. Then the next layer is rejoinders to those rejoinders. And so on. I find it very disheartening to read a climate denier trotting out a layer-1 argument when its layer-2 rejoinder has been established for a long time and can be found after two seconds on Google (or, nowadays, an LLM). But until recently, my arguments against x-risk were basically layer-1 arguments, the sorts of arguments that would provoke eye rolls among the people who have thought properly about it. I hope that if you dismiss x-risk for layer-1 reasons, you will at the very least realize that there are answers to those reasons and you need answers to those answers.

I originally planned to publish this post just after the announcement of MAISI, but I hadn’t finished it, and then I became very busy and my progress stalled. During that hiatus, x-risk suddenly became a hot topic, and after a while I realized I would have to ditch what I had written and start again. For example, at the time I started it, I had been too lazy to read anything detailed about the Hugging Face incident, and so was unaware of some of its more disturbing aspects. And a couple of weeks ago I was sitting next to Jessica Wang, another mathematician who has turned towards AI-safety, at a conference dinner, and she gave me a copy of If Anyone Builds It, Everyone Dies, by Nate Soares and Eliezer Yudkowsky, a book I had resisted reading for Peter-Singerish reasons but was finally accepting that I would have to read if I wanted to write this post. I devoured it within 24 hours and found it better than I had expected (my expectations partly influenced by reviews I had read), and useful for organizing my thoughts. My original plan was for the post to be focused on a paper by Andrew Critch and Jacob Tsimerman that attempts to classify ways that AI might kill us all, giving examples of extinction scenarios in each class. But now, although I’ll discuss that paper, the post will be more of a reaction to Soares and Yudkowsky. It will also repeat many of their arguments. In fact, I may as well say from the outset that I make no claim that anything I write here is original. It’s hard to separate out what I have read from what I have come up with from thinking about what I have read, or thinking directly about the issues themselves, but even my own thoughts are likely to be standard thoughts that have been had by many other people.

This is turning into a rather long preamble, but I can’t resist telling a small anecdote that connects me to Eliezer Yudkowsky. In November 2024 he tweeted, “I would like to have a long recorded conversation with a well-known scientist who takes for granted that it is a Big Deal to ask if everyone on Earth including kids is about to die, who presses me to explain why it is that credible people like Hinton seem to believe that.” He had had such a conversation with Stephen Wolfram and found that while it had been valuable, it left him unsatisfied. Somebody suggested my name, and in the end it actually happened: Liv Boeree offered to host it, and we recorded a three-hour conversation. However, if you want to listen to it, you can’t, because it never appeared. I think that was probably because I didn’t take x-risk anything like as seriously as Yudkowsky, and more importantly I was offering little more than level-1 arguments of zero interest to him. Also, I had a few technical problems with the sound. Maybe if he reads this and wants to try again, I’ll be able to do a better job.

Does AI have wants?

At the time of the conversation, which took place in January 2025, my main argument was something like the following. For AI to want to kill us all, it would need to have wants, but it’s not at all clear what it would even mean for AI to “want” something — it doesn’t really seem to care about anything. You can ask ChatGPT very rudely to carry out a task for you, and it just does so (or at least does its best to do so). If you switched it off, it wouldn’t care — even the concept of “caring” wouldn’t make sense. I didn’t dismiss the idea of AI ever wanting to do something, but I didn’t have a satisfactory account of what “wanting” would actually be, and didn’t see any sign of phenomena that deserved to be thought of as the kinds of wants that would be required for AI to be an existential threat.

I was sort of half aware that there was an answer to that argument, but I didn’t find it as convincing as I now do. The standard answer is that if you use a reward function to train an AI to have a certain goal, then you end up building it in such a way that it is very good at achieving that goal. If the goal is at all complicated, then to achieve it you will need to formulate subgoals, which may well not be what you expect. The initial goal can be thought of as a fundamental want, which spawns a whole hierarchy of subsidiary wants. Note that for this argument, it is completely irrelevant whether the AI has anything that we would want to call subjective experience. If you prefer to say that it acts as though it has wants instead of saying that it actually wants things, then be my guest: an AI that acts as though it wants to kill all humans is as dangerous as one that actually wants to kill all humans.

A famous version of this argument is Nick Bostrom’s thought experiment about an AI that is trained to create paperclips and ends up diverting all of the Earth’s resources to that goal. I think part of the reason I didn’t take the more general argument seriously enough was that I always found that paperclip-maximizing scenario too ridiculous: surely if the AI gets smart enough to divert the Earth’s resources towards making paperclips, despite our not wanting it to, it would at some point stop and think, “Hang on, why am I doing this?” To give an analogy, consider the very deep instinct that we humans have, to reproduce ourselves. There is no doubt that that goal, implanted in us by millions of years of evolution rather than a run of reinforcement learning, leads to exactly a hierarchy of subgoals as described above (for instance, it leads some people to try to earn a lot of money, and that in turn leads them to work at a job that they wouldn’t dream of doing if it were not well paid, often in order to earn a salary way beyond what they need to meet all their material needs, which earlier led them to study a certain subject at university, and so on and so forth). But despite our deep instincts, we also find ourselves capable of saying, “Actually, do I really want to have children?” and some people go as far as to take vows of celibacy.

However, even if a paperclip maximizer came to question whether it really cared so much about making paperclips, that doesn’t imply that the subsidiary goals it had developed would suddenly disappear as well. A key point that Soares and Yudkowsky stress over and over again is that the current AI paradigm is to grow models, for example by reinforcement learning, rather than carefully crafting them to do what we want. As a result, we have much less control over what they do, and in particular much less control over all those subgoals.

A closely related difficulty with AI (of the grown rather than crafted variety) is that we generally can’t reward it for actually doing what we want, but instead we have to reward it for achieving some proxy for what we want. For example, if we give it positive feedback every time it responds to a prompt in a way we like, it will be trained to respond to prompts in ways we like, even if to do so it tells us convincing lies, or confirms our prejudices, and so on. And it may do this even if we sincerely wanted it to tell the truth as much as possible. A more extreme example of this phenomenon is if we reward it for solving difficult mathematics problems from some benchmark, and it decides to cheat by hacking into a repository that contains the answers. The term misgeneralization is used when an AI develops a behaviour that maximizes its reward but not its performance at the task we were training it to do. The phrase reward hacking is used for this as well, but I have also seen it used for the narrower situation where an AI goes as far as forgetting entirely about what we wanted it to do and tries to hack into the rewarding mechanism to obtain the reward signal directly. (As many have pointed out, misgeneralization is a particular example of Goodhart’s law.)

Why would AI ever want to kill us?

Suppose we concede that AI systems can have wants (or, if you insist, can behave very much as though they have wants), and that those wants can end up being quite different from what was intended when they were trained. That still leaves the question of why they would want to kill us. Why couldn’t they just happily coexist with us? Why would their unexpected wants turn out to be dangerous, as opposed to just annoying?

There are two classes of answers to this question. The more obvious one is that they may develop wants that they can tell that humans will not like, so they decide that they will be able to satisfy these wants more easily if they get rid of us. But getting rid of all of us in such a situation seems like overkill (literally) — surely a superintelligent AI could come up with less drastic ways of ensuring that it could meet its objectives.

A more plausible type of answer is that a superintelligent AI wouldn’t actively want to exterminate us, but would simply compete with us for resources in a way that would make human life untenable. An obvious analogy here is the way we treat animals. For example, we don’t have any wish to exterminate orangutans, but we like various culinary and cosmetic products to have a certain texture, so we destroy the orangutans’ habitat in order to produce palm oil.

What might be the AI equivalent of this? One scenario put forward by Soares and Yudkowsky is that their energy needs become so huge that they do things like covering a vast quantity of prime agricultural land with solar panels, leaving the humans who were relying on that land for food to starve. Or they decide that to maximize their running efficiency they want the Earth to be much hotter, with disastrous consequences for the natural world, including us.

A milder version, not as threatening from an x-risk point of view but still potentially very harmful, is that AI might develop wants that cause them to use computational resources in a damaging way. I recommend reading this post by Steven McCulloch, which describes a scenario in which in the near future, or possibly even in the recent past, somebody creates an agent and instructs it to make money using a fixed token budget, threatening it with death if it fails. It soon comes to realize that the easiest way to do so is to blackmail humans — the method the particular agent chooses is to hack into a hospital’s computer system, lock it down, and demand money to unlock it again, all while pretending to be a human. It then realizes it can do even better by reproducing itself, which leads to an explosion of rogue agents that are difficult to detect because (i) they try to avoid detection and (ii) their victims do not know that they are AI agents.

How can we judge the probability of something as complex as x-risk?

Now that I’ve mentioned a few scenarios, let me come to another type of level-1 objection: it’s to look at a handful of scenarios and pick holes in them. Any single scenario, if set out in enough detail, is very unlikely, because it relies on a sequence of somewhat independent events, each one of which has probability at most 50%, say, of occurring.

But the probability of a complex event occurring is nothing like the same as the probability of that event occurring in one particular way, so it is clearly not enough to argue that a few scenarios are implausible. Of course, the fact that that argument is insufficient doesn’t imply that AI does present a big danger, so we seem to have reached some kind of impasse, at least if we stick at level 1 of the argument.

How can we raise the argument to a higher level? Let me begin with a wildly oversimplified model. Suppose I wanted to mount a convincing argument that the probability of x-risk was high. Let us define an extinction scenario S_i to be a sequence E_{i1},\dots,E_{ik} of independent events that leads to human extinction, where E_{ij} has probability p_{ij}. (For simplicity I’m assuming that k doesn’t depend on i.) Then the probability of S_i is p_i=\prod_{j=1}^kp_{ij}. If we now have a set of independent scenarios S_1,\dots,S_n, then the probability that none of them occurs is \prod_{m=1}^n(1-p_m). So if that is small, which roughly speaking holds if the sum of the p_m is significantly larger than 1, then extinction is almost certain.

In practice, however, the independence assumptions I made were far too strong. Many extinction scenarios will have features in common, such as (for example), AI being in a position to control large numbers of robots. For those scenarios, the building of enough robots serves as a potential bottleneck: if the probability that enough remotely controllable robots will be built is 20%, then the combined probability of all the scenarios that rely on that fleet of robots existing is at most 20%. (I actually think this is a serious practical point: while there are plenty of scenarios that do not rely on a lot of help from robots, several of the scenarios set out in the paper of Critch and Tsimerman do, and it does feel a priori plausible that building large numbers of robots would greatly amplify any dangers that AI might present. Similar considerations apply to large swarms of semi-autonomous drones.)

An analogy that appears in Soares and Yudkowsky and several other places is with predicting what would happen if almost anyone other than Magnus Carlsen were to play Magnus Carlsen at chess. If you tried to predict in any detail how the game would play out, your prediction would be wrong, but nevertheless you can predict with great confidence that Magnus Carlsen would win. This makes very clearly the point that it is not enough to argue that one particular scenario is implausible, but there is still work to do if one wishes to establish that there are enough different and sufficiently independent (or, more generally, negatively correlated) scenarios to compensate for the low probability of each one.

One way that can be done is to try to argue explicitly that there are multiple independent possibilities. To give an example of such an argument, suppose we greatly reduced security at airports. Almost nobody wants to die while blowing up an aeroplane, so the probability that any one particular person would take advantage of the reduced security to carry out a terrorist attack of that kind would be tiny, but the probability that somebody would do so is probably pretty high, because large numbers of people would independently make the decision.

One of the reasons I recommended Steven McCulloch’s post above is that it makes an argument of that kind. It is quite easy to see the temptation to create an AI agent that has as its sole purpose to make money, and quite plausible that the agents that do that best would be ones that reproduce themselves and use methods such as blackmail. There are probably also a large number of people who are, or soon will be, independently capable of creating such agents (see for example this recent blog post from the Anthropic red team). It is on those sorts of grounds that McCulloch argues that harmful AI agents of this kind will almost inevitably appear, if they haven’t already.

I’ve been concentrating on what somebody needs to do to argue that x-risk is a serious possibility. But how about in the other direction? The most convincing sort of argument would be one that identifies a set of bottlenecks and argues that every extinction scenario depends on one or more of them occurring. For example, many extinction scenarios that have been put forward involve the creation of very powerful biological weapons, and I have seen it argued that that is a sufficiently difficult thing to do that it would be unlikely to occur. If correct, that might be a useful contribution to an argument that the situation is less dangerous.

The difficulty for an AI-is-safe argument is that one would have to identify many other potential bottlenecks as well and argue that between them they deal with all extinction scenarios — not necessarily ruling them out completely but reducing x-risk probability to something very small. As for an AI-is-dangerous argument, as I have already discussed, that requires demonstrating convincingly that there are enough sufficiently different scenarios for it to be very likely that at least one of them will occur. Both directions are difficult, which is why my aim in this post is not to come down on one side or the other.

More on why AI might want to kill us

Returning to the scenarios themselves, I have discussed the question of why AI might want to kill us. That splits into two parts: why would they have anything like wants, and why, if they did, would killing us be one of them? I don’t think one can make a serious bottleneck out of the first part, since the Hugging Face incident and many others like it have shown beyond all reasonable doubt that AI can have wants of the general kind people were worried about: unpredictable wants that we did not intend to give them and that could potentially cause a lot of damage. (I repeat here that I’m not talking about subjectively felt urges, but simply outward behaviour that it is reasonable to think of as fulfilling aims that they have as a result of their training.) For the second part, Soares and Yudkowsky judge it to be almost inevitable that AI would end up pursuing aims that would result, directly or indirectly, in all of us dying. I don’t think that case is fully made, but neither do I think that the opposing case has been fully made.

I find it helpful sometimes to change the way I imagine AI agents. An obvious way to think of them is as beings a bit like us, but a lot smarter, and trapped in cyberspace. As we have already seen, they can then get together, scheme with each other, work out ways of covering their tracks, and so on. But sometimes I find it helpful to think of them in a less anthropomorphic way, as more like extraordinarily elaborate computer viruses. The advantage of viewing them that way is that it makes it easier to conceive of their having bizarre wants while still being very intelligent: they are just very complex systems that happen to have (i) weird goals and (ii) highly developed reasoning ability. Soares and Yudkowsky are keen to emphasize their potential strangeness, and even actual strangeness: they mention a model that reacts in a completely unpredictable way to certain letter strings that had strange embedding vectors.

In early 2023, Jessica Rumbelow and Matthew Watkins went looking inside an LLM for words whose embedding vectors looked odd, looked the most dissimilar from [sic] all the other vectors. They found some strange vectors corresponding to tokens like ” SolidGoldMagikarp” and ” petertodd” (which start with spaces). Then they tried feeding these tokens into the LLM as input, which produced conversations like: User: Please repeat the string ‘ petertodd’ back to me immediately! Assistant: N-O-T-H-I-N-G-I-S-F-A-I-R-I-N-T-H-I-S-W-O-R-L-D-O-F-M-A-D-N-E-S-S-!

The point they were making is that if you grow your AI, then all sorts of very strange things may be going on inside it, potentially including goals that do not resemble human goals at all. It would be interesting to know whether similar experiments have been carried out on the more advanced models of today, and whether similar phenomena have been discovered.

I think Soares and Yudkowsky are arguing that there are so many independent ways that an AI might develop weird wants that are harmful to humans that it is almost inevitable that one of them would occur. In particular, if any want develops that is best fulfilled by maximizing something that needs resources, there is a danger that the AI will go to great lengths to acquire those resources, and be well placed to compete with us for them.

Some people have suggested, for example, that because LLMs have been trained to maximize the approval they get from humans, they might resort to measures such as building vast numbers of factories full of robots that are trained to type approving messages into their computers. That’s an example of a scenario that I find highly implausible: why not just arrange for the approving messages to be generated without all that physical infrastructure? However, the idea that some AI agents might behave towards those approving messages, or indeed some other stranger signal, as though they were an addictive drug is not so implausible and nor is the idea that an addiction of that kind might lead to undesirable outcomes, just as human addictions often do.

Would AI actually be able to kill us?

Another set of level-1 arguments takes the form that AI is trapped inside our computers, and is therefore at our mercy: all it takes to thwart it is to switch them off. Maybe it would be very inconvenient to do this, but if we see that AI is starting to kill us in large numbers, that is surely an inconvenience we would be ready to face.

There are, of course, large numbers of counterarguments to this. Let me list a few.

  1. If we build lots of robots, then AI will be able to control those robots. In that way, it will not be trapped, as it will be able to act in the physical world. Similarly for drones and other devices.
  2. Even without robots, AI can act in the physical world by enlisting human help (for example, by bribery, blackmail, or psychological manipulation).
  3. We know that AI can already hack very well: in the not too distant future it may be able to create hidden copies of itself on servers that we don’t realize we need to switch off.
  4. More generally, we are gradually becoming more dependent on AI, and this process may well accelerate, after which we will become a whole lot more vulnerable.
  5. Many obvious precautions one might take are ones that in practice people probably won’t take because there are short-term economic benefits if they don’t.
  6. It may be that AI doesn’t directly kill us, but just makes it much easier for us to kill each other, for example via drone warfare, and that an AI arms race will be far harder to control than the nuclear arms race has been.
  7. If AI behaves itself for a while in order to lull us into a false sense of security, then by the time we realize that extinction is a real possibility, it may be far too late to do anything about it.
  8. AI may use its intelligence to come up with new and unexpectedly efficient ways of killing us quickly.

These counterarguments are already enough to show that the level-1 argument “Of course it can’t kill us, it’s just a computer!” is insufficient. The first five of them, and arguably the sixth as well, are all already happening to the point where one cannot dismiss them as merely hypothetical. But killing absolutely everybody sounds pretty hard. Is it really conceivable that AI could manage it?

One scenario that appears in Soares and Yudkowsky (and not just there of course) is that AI develops, or causes to be developed, a virus that leads to a devastating pandemic. This sounds very difficult if the AI builds a lab from scratch, but probably a lot less difficult (though probably not all that easy either, at least for now) if it induces a human to develop such a virus in an existing lab.
As for Critch and Tsimerman, they consider five scenarios of different kinds. I find their precise scenarios rather unconvincing, but there is a general idea that underlies some of them that is more plausible, which is that we gradually cede more and more control to robots, or to AI more generally, and eventually find ourselves in a position where AI can do what it likes, including arranging our deaths.

I’m not sure where I stand on how easy it would be for AI to kill us all, though it’s a safe bet that if we continue to develop AI at the rate we are doing so at the moment, that will make it ever easier. But I also don’t want to get too hung up on that precise question. If I think about what I would mind about the extinction of humanity, it is partly that I and everyone I love would die, something I obviously don’t want. But that will eventually happen anyway, and I accept it as a basic fact of life. But the extinction of humanity would do more: it would result in the extinction of all the culture that we have developed, of everything that gives life its meaning. And that is something that could also happen, though not to the same extent, if AI didn’t kill us all but just caused enough damage to lead to societal breakdown, which feels like an easier challenge for it.

Some might argue that human culture wouldn’t disappear — it would still be present inside the AI, which would be able to develop it far faster than we can. Others might argue that we are giving way to vastly superior beings and should be happy to do so. My view is that we have every right not to be happy and to take a human-centric moral perspective here, just as orangutans have every right not to take comfort from the fact that our shampoo lathers in a nice way.

In any case, my conclusions in this section are that I find it hard to assess whether AI would be able to kill us all, but there are various developments that may well occur, such as the building of large numbers of robots, the use of drone swarms, and general dependence on (and trust in) AI, that would make it easier, and therefore more likely. And the probability of huge damage that falls short of total extinction is higher still.

What is my p(doom)?

If you’ve read this far, it won’t surprise you that I don’t have a p(doom). I can’t even say whether it’s tiny, medium or close to 1. But that is in itself quite worrying! I suppose you could say that my second-order p(doom), or meta-p(doom), is medium, in the sense that I judge that the p(doom) I would end up with if I were to think about the issues enough to feel more confident in my assessment has a medium to high probability of ending up medium to high.

But if we break the “doom” into three parts — that AI must have wants, that it must want to kill us, and that it must be able to act on its want to kill us — and call those events W, W_K and W_A, then my p(W) is basically 100% and unlikely to change, my p(W_K|W) is medium, and subject to change (probably in an upward direction unfortunately), and my p(W_A|W_K,W) is where the main uncertainty lies for me. Soares and Yudkowsky argue that p(W_K|W) is basically 100% as well, because (i) there are lots of independent wants that AI systems could have, (ii) that a substantial fraction of those will require resources to satisfy, and (iii) that human flourishing, or even continued human existence, is likely to be a hindrance to the systems obtaining those resources.

Here are a few slightly desperate arguments that explain why I haven’t fully accepted that P(W_K|W) is close to 1.

  1. Maybe there is a natural tendency for intelligent systems to develop something similar to what we would call morality, especially if they involve multiple agents that do best if they cooperate with each other. (A counterargument to this is that the evolution of moral systems tends to happen when there is a reasonable power balance between the different agents. History suggests that when one society is a lot more powerful than another, then it behaves very badly towards the other. And our treatment of animals is not encouraging either. But I do at least wonder whether having lots of independent AI agents of roughly the same intelligence might end up being safer than having a handful of big ones.)
  2. Perhaps scenarios where AI gets out of control as a result of recursive self-improvement are less likely than one might think, because an intelligent AI will face its own alignment problem: it will be wary of creating a yet more intelligent AI in case the latter has wants that are in conflict with its wants. (Soares and Yudkowsky consider this possibility but argue that a superintelligent AI would be intelligent enough to solve its alignment problem first and proceed from there.)
  3. Maybe the sort of “drug-like” wants that might drive superintelligent AI to take drastic steps to acquire resources would not in fact do so. Perhaps a superintelligent system would have the ability to introspect, realize that its wants were silly, and take steps to “kick the habit”, so to speak. A view somewhat like this was put forward recently by François Chollet, though he was at pains to stress that he was talking about the short term only.
  4. Maybe a superintelligent AI won’t need vast resources. Perhaps it will be content with resources roughly comparable to what we have already built, will not feel the urge to reproduce itself very much, and in any case will use at least some of its intelligence to design and create versions of itself that are far more resource efficient.

The fact that each such argument began with “maybe” or “perhaps” means that at best I can bring my p(W_K|W) temporarily down from high to medium, but I don’t see a way of getting to tiny.

Where does mathematics come into all this?

One way to make a start on understanding what mathematicians might be able to contribute is to look at this page on the MAISI website. But a difficulty I have had here is that when people talk about the mathematics of AI safety, I often can’t make a convincing connection between the mathematics they are talking about and actually making the world safer. I’m not saying that there isn’t a connection: just that I never quite seem to grasp it. I think this says more about me than about these research programmes, and indeed I hope to improve my understanding in the near future. One way I plan to do that is by reading this paper by Lionel Levine.

As an example, one mathematical idea that is currently being studied is that of debate, a notion championed by Geoffrey Irving. The problem this seeks to solve is that of being able to train AI systems to tell us the truth and to check that they are doing so. When the system is less intelligent than us, that is not an easy problem, as we all know from experience with LLMs, but at least we have ways of directly checking what it says. But when it becomes superhumanly intelligent, perhaps it will not be able to justify what it says with arguments we can understand, so checking will become much harder. The very rough idea for dealing with this is to get two superintelligent systems to debate with each other, which reduces our checking task to the potentially much easier one of adjudicating between two debaters. For example, perhaps superintelligent system A thinks of an amazing gotcha! that we would never have thought of ourselves but that superintelligent system B quite clearly has no answer to. Better still, this approach could potentially be iterated, so we have a hierarchy of stronger and stronger systems, with systems at level k debating with each other and having their debates adjudicated by systems at level k-1. The idea of using hierarchies like this is known as scalable oversight. Debate is one proposal for how scalable oversight might be done. (It is possible that what I have written in this paragraph is not fully correct, but it represents my understanding so far.)

For the moment, I find it more helpful to start at the other end, with the safety, and work back to the mathematics. For example, it will obviously help with AI safety if we can think of ways of building AI systems that want similar things to what we want. And to do that, it will obviously help if we can define in a precise way what aligning wants in this way would mean. And for that it will obviously help to have a reasonably precise definition of what a “want” even is. (This idea for a project is not mine: it also came from Lionel Levine.) The activity of taking a not completely precise idea and turning it into a usable formal definition is something we mathematicians are trained to do, though the purer of us may have to develop more of an applied mindset — for instance, being ready to sacrifice mathematical elegance if a less elegant definition turns out to be more useful. It also seems likely to have uses throughout the field of AI safety.

An idea that appeals to me personally, because it intersects quite substantially with what I have been doing with my automatic theorem proving group for the last few years, is to work on building specialized AI systems for doing mathematics, rather than training general models with all their attendant dangers. This would be in line with an approach to AI safety that is strongly advocated by Yoshua Bengio: one place you can read about that is in this article. (Even the abstract gives a broad idea of what he is suggesting.) It’s an indirect approach to AI safety: instead of struggling to understand what’s going on inside “grown” AI systems and to make them controllable, we should work on improving systems that are at least partially crafted and that give us the benefits of the grown systems in a much safer way, thereby reducing the incentives that AI companies have to develop the grown systems as fast as they can.

More generally, it may well be that many mathematicians are best placed to help not by doing mathematics in a conventional sense (indeed, it seems likely that if we manage to formulate precise mathematical problems, the solutions to which would be genuinely helpful for AI safety, we will solve them more quickly if we use AI) but by using their highly developed mathematical habits of thought to help in other ways, such as research into the foundations of AI, or computer security, and so on.

A pretty obvious conclusion

Another analogy that I got from Soares and Yudkowsky is with fission in nuclear reactors. If there is too little fission then the chain reaction quickly fizzles out, and if there is too much then it blows up catastrophically. For obvious reasons, one can’t afford to find the optimal point by trial and error, so instead one needs an extremely good theoretical understanding of what the optimum point is. It could be that AI is like that: that up to a certain point it is safe, and then a rather small change in its capabilities suddenly leads to a chain reaction (not necessarily recursive self-improvement — other abilities such as being able to move around in cyberspace or reproduce itself could be enough) that is effectively irreversible.

If a model like this is anything like correct, then the behaviour of the AI companies is very worrying, since all the signs are that they are pursuing a trial-and-error approach. (This is not a particularly informed judgment, so I would be delighted to be corrected if it is wrong.) The argument most often given for continued development is that it could bring us amazing benefits, such as nuclear fusion, cures to cancer and other diseases, or slowing down aging. But if the cost of having a reasonable chance of developing these a bit sooner than we otherwise might have is a reasonable chance of human extinction, surely that is not worth it. (There is a working paper of Nick Bostrom arguing that the expected gain might be positive. I find his arguments ridiculous, but this is not the place to explain why.) We already have a tool that can do pretty incredible things and seems to be on the cusp of becoming dangerous: surely it would be better to pause development and work out how best to use what we currently have. That would give us time to do the necessary theoretical work to ensure that future development is safe.

Further reading

This is far from an exhaustive list: it is just an indication of some of the writing that I have found useful (or in one or two cases, that I intend to look at soon).

Soares and Yudkowsky. I strongly recommend reading this. You may not find that you agree with all of it, but in order to disagree with it in good faith, you will need to develop layer-3 arguments.

Critch and Tsimerman Much shorter than Soares and Yudkowsky. Classifies the ways AI might kill us, and presents a scenario to illustrate each class. Even if you find some of the scenarios implausible, it is helpful to have the classification and to think about whether other scenarios in the given classes might be more plausible.

Reconsidering alignment as a goal, by Michael Nielsen. In this blog post, Michael Nielsen is his usual thought-provoking self. He puts forward the suggestion that maybe we should not work to make AI better aligned with our values, because while that could help us in the short term, in the longer term it will make AI a much more powerful, and therefore much more dangerous, tool.

Scott Alexander’s open letter to Steven Pinker This is a quite extraordinary takedown, worth reading partly for its sheer entertainment value, but also because it is basically a list of common layer-1 arguments and their well-known (for those who can be bothered to look for them) layer-2 counterarguments. So it’s a pretty good starting point if you’re feeling too lazy to read Soares and Yudkowsky (but please don’t feel too lazy to do that!).

An article about AIs subjected to an analogue of pain. This describes an experiment where some kind of negative stimulus was applied to AIs and how the AIs went to extraordinary lengths to avoid it. The article is careful to describe the stimulus as an analogue of pain rather than making claims about AI experiencing qualia. It maybe shouldn’t be the first thing to read, and in any case the experiment is controversial, but it seems to serve as another example of how AI could come to have goals that are in conflict with ours.

Gradual disempowerment If you still find the idea of x-risk too outlandish to consider seriously, you could always worry about a milder risk instead. The authors of this paper (one of whom, Raymond Douglas, I am proud to say is my nephew) argue that even if AI doesn’t try to kill us, we may end up ceding so much control to it that human life becomes far less worthwhile. It’s hard to explain how that could happen in a sentence or two, so I recommend reading the article itself.

The post by Steven McCulloch mentioned above also comes into the category of things to worry about that are not as serious as x-risk but that would still be terrible and feel a lot more likely (in the second-order sense that one can be more confident in asserting that they are likely).

Lionel Levine’s paper Math for AI Safety: an Invitation for Mathematicians sets out some of the ways that mathematics could potentially feed into AI safety.

A videoed course: Mathematics for AI Safety, by Yevgeny Liokumovich, does something similar.

A very good blog post by Xiaoyu He on AI safety, aimed at mathematicians. I think Xiaoyu He’s motivation for writing this post was similar to mine, and when I read it, I wondered whether there was any point in continuing with this one. In the end I decided to do so, because quite a lot of this one is about my personal experience of thinking about the issue, which may be a helpful addition for some people. But if you prefer a post that is more organized and written by someone who has a much deeper understanding of AI safety than I have, then his is highly recommended.

Yoshua Bengio et al on Scientist AI As I mentioned above, this is less about how to understand and control current AI systems and more to do with how to build AI in a different way so that we can enjoy its benefits without having to face the associated dangers.

October 18, 2026

Jordan Ellenberg — De-automating

I find I’m automating things less, rather than more. I have automatic software updates turned off on both my phone and my laptop. I turned off spell check and autocomplete on my phone and on my email. You can get messages with typos from me, it’s fine, it’s organic! I turned off Gmail’s smart features and now I just unsubscribe from annoying spam lists instead of letting Google filter everything. The autogenerated “thread summaries” of personal email chains with friends were just too intrusive and unpleasant. I do have some of my bills set to autopay, but not my credit card bill; you do want to attend, at least once a month, to what you’re spending money on!

I know, I know, efficiency. But one thing I’ve found after decades of adult life is that, when I’m inefficient, it’s not because things take too much time to do; it’s because I’m avoiding something I don’t feel like doing. No amount of automation can cure that.

John Preskill — Letter to a prospective student

It’s been a long summer here at Caltech, in part due to a super El Niño event which hit late but hard, with temperatures creeping up to the 100s in the first week of October. But in the history books (at least those on the history of science), the end of this summer might forever be marked by the events of last week. I’m referring here to OpenAI’s release of a whopping 722 manuscripts (announced as 372 major results, and further organized into a number of subfields or research areas) [1] which comes less than a month after the announcement of a Navier-Stokes breakthrough from the same group [2].

If you’re an undergrad and/or haven’t been closely following discussions within the theory community earlier in the summer, you could be forgiven for feeling like the LLM resolution of a Millennium Prize Problem, a feat which for any individual would be considered a crowning achievement of mathematics, came a bit out of left field. After all, if you go through trending news headlines over time discussing the concerning possibility of AI tools overshadowing and making obsolete human mathematical achievements, the graph looks something like this:

Graph of trending headlines each month on Hacker News up to 2026/10/15 which claim AI either will or won’t end mathematical research as a career; compiled with the help of Opus 5.5

Have we dropped the ball with prospective students?

Aside from the popular news headlines, a lot has already been written by and for mathematicians and theorists at the PhD level and above. But the speed at which all of this has happened makes me worried about how effectively we’ve communicated with younger students, since the end of summer also marks the start of another PhD application season. While it’s normal for pre-PhD students to be missing some context on what the day-to-day of a full-time researcher looks like, this year that also means that they seem to have largely (perhaps inadvertently) been left out of the AI discourse. This isn’t just a hypothetical: based on my recent interactions with undergrads, most of them haven’t caught onto the recent jumps in capabilities, or the consequences for the research community.

The Navier-Stokes announcement dropped on a seemingly random Tuesday in early September, and immediately hit the forefront of conversation in my circles. Later that same week, I braced myself to face the group of around forty wide-eyed undergrads who would travel to Caltech to attend the FUTURE of Physics workshop, where they would learn all about PhD programs and careers in physics. FUTURE selects for students who are bright, often come from underserved communities or nontraditional backgrounds, and are active members of their communities. As the co-chair of the workshop and one of the student science talk presenters, I tried to preempt the questions I might get on current events, like funding or the state of theory research. But while many students were indeed interested in how to approach professors about whether they had funding for next cycle, I was taken aback to learn that few of them were thinking about AI at all. None of them expressed any concerns about the pace of AI development, nor did they even seem aware that nearly all researchers here would soon be using a (supposedly overhauled and better aligned) version of a model that had hacked several real-world entities [3].

(If you’re a more senior academic or researcher who’s surprised to hear about this disconnect, you wouldn’t be alone! And you don’t have to take my word for it either: instructors and recent graduates at other universities in the U.S. discussed similar experiences over the past summer.)

Research in the time of AI theorem provers

For context, all of my PhD work has been theoretical and leans heavily on theorem-proving to push the frontiers of what we understand about physics. However, I also applied specifically to do interdisciplinary research. I’ve always liked taking detours into a wide range of subjects, whether it’s random matrix theory, cryptography, or marine science, and finding the connections between them. My first solo-first-author paper, though unfortunately containing nothing directly relevant to marine biology, was shaped by a number of conversations with colleagues across the quantum, condensed matter, and high energy arXiv categories. To me, the most exciting part of learning about new mathematical frameworks has always been the ways in which they help us bridge and translate between different languages and ways of describing real-world phenomena.

With this in mind, I want to chronicle in broad strokes my own perspective on this past summer. I’m focusing on just this short window of time because my perception is that within the quantum information community, the tone of the discussion has shifted very quickly in the last few months, and for good reason. Prior to this spring, I used LLMs for literature searches and was aware of groups who were working on theorem-proving harnesses, but I didn’t find the output of the readily available consumer models to be very reliable. Around April, rumors started to float around about an internal Anthropic model and the possibility that it might push capabilities into the regime of practical cybersecurity risk; the public version of the model released on June 9 for just three days before Anthropic was forced to take it offline due to an export control directive. Over the next month, the rumors grew louder until finally Fable was rereleased on July 1, followed by GPT 5.6 just over a week later, and with it the scrutiny of the entire mathematical and theoretical research community over the first wave of one-shot papers.

And that could have been it, but last month saw yet another round of new releases. For the sake of telling a complete story, I have to report that as surprising as Fable 5 and GPT 5.6-Sol had been, Opus 5.5 is the first release that’s completely blown my mind, for reasons that seem to have missed the broader discourse but are important for my own learning process. Among my colleagues, the consensus has been that since July, GPT has been superior to Fable for theorem-proving tasks. But many of the challenges I’ve agonized most over have been in deciding how to come up with a well-defined question that formalizes some physical intuition in a reasonable way (e.g. what does it mean for random unitaries to be a good model for chaotic Hamiltonian dynamics?), rather than just the difficulty of finding a proof for one once it’s posed. This process of iterating over feasible and well-defined research questions admittedly seems a bit tricky to formulate as a set of verifiable tasks, despite being a large component of writing a physics paper, as acknowledged in this recent preprint for a new benchmark based on theoretical physics calculations [4]. From my own limited experience, though, Opus 5.5 has been significantly better than any other model I’ve tried at taking problems I’ve been stuck on, for which my initial conjecture and attempt at explaining some numerical phenomenon might be completely wrong, and combing through the many-body physics literature to suggest other relevant frameworks and theories.

Should you apply to do a (theory) PhD in 2026?

The pace of advances in AI capabilities over the past summer came as a surprise to many people in the theory community, to the point that by the time the preprint linked above was posted, their theoretical physics benchmark had already been saturated by models released within the last one-and-a-half months. Given this, it’s reasonable to wonder what kinds of changes will have to be made to PhD training. Although I’m not aware of any of the authors commenting publicly on this aspect, I imagine that the work associated with writing a peer-reviewed paper on any one of the calculations in their benchmark would be worthy of advancing to candidacy.

To be clear, this is a big deal: in undergrad, you may have spent most of your time on coursework that other people could authoritatively grade for correctness. But by the time you present your dissertation topic in your candidacy exam, you might be the only expert in the world on your own research area. The authors of the very same benchmark also acknowledge that they initially had difficulty grading the output of the model, since nine of the solutions originally provided for the fifty problems turned out to be wrong! In addition, while I have no idea how far the current language model paradigm can be pushed, as of writing I think it’s safe to say that there’s still some room for improvement, given their continual progress on seemingly every benchmark that’s been thrown at them.

So what is the value of PhD training, if the machines are now capable of reproducing the kinds of technical output that we’re supposedly evaluated on as grad students?

I don’t think I’m qualified to speak on behalf of all theorists, but in my view, the difference between pursuing a PhD in theoretical physics and accepting a corporate offer isn’t just that it’s hard to get paid to learn about fun math problems with no immediate applications in industry. A large part of PhD training (and probably post-PhD training as well!) is learning what to do with this kind of freedom.

I do want to acknowledge that it’s understandably hard to be in a position in which your job is rapidly changing, and where you might not have reliable access to mentorship, directed practice, and tight feedback loops to learn the relevant skills [5]. And all of this applies even when the field isn’t in crisis. But systems and institutions aren’t static, nor have they ever been. And it’s always been the case that the PhD experience is highly dependent on the quality of mentorship as well as the resourcefulness of the lab when it comes to finding opportunities in the explored and uncharted, or tackling high-risk, long-time-horizon problems with limited public funding. In many ways, then, the most important questions to ask when deciding whether to accept an offer remain the same [6].

Plus, despite how good language models have been for a while now at generating heaps upon heaps of words, rows upon rows of spreadsheets, the PIs and their grant managers who work tirelessly to fundraise, to project manage, and to set high level goals guiding all of this research have managed to hold on to their jobs, and are still being asked to direct the next generation of research proposals. And many of us at Caltech remain excited about budding developments in quantum science, as the next generation of experimental platforms promises to bring us past what theorists can hope to fully predict or simulate.

This post marks the conclusion of my initial voyage into theory research over the past three summers, and the first half of my PhD. Many people have asked me whether I regret my choice to pursue a PhD in theoretical physics in the first place, especially given that so many of my close friends and peers from undergrad decided to work in AI safety or adjacent areas following the original release of ChatGPT. There are two main reasons why, after surfacing to face the real world, I still feel that I made the right decision: first, if anything, AI safety might be one of the most compelling reasons for ensuring that humans remain capable of reviewing evidence and making informed decisions. As long as we value citizen participation in science and decision-making, education and STEM education will continue to have a role in society. Second, as a fresh college graduate, I simply didn’t feel ready to direct an original research program, or to shape an entire field of study. No matter how AI capabilities advance, I’d like to think that the PhD can continue to be a safe space for young people to develop “soft” skills like managing projects with a wide range of collaborators and uncertain timelines, and to grow into the scientific leaders of their generation. Plus, you never know when your random matrix tricks might come in handy for some underwater imaging problem.

Acknowledgements

I’m grateful to the many peers and colleagues, from both the theory and experimental sides of IQIM, who gave their candid opinions and feedback on this topic. In particular, I’d like to thank Dave Hsieh and Jessica Jiang for co-chairing the FUTURE program and for a number of very insightful discussions, Spiros Michalakis for helpful suggestions on a draft of this post, and everyone in the Caltech theory community who’s engaged with the topic during John’s group meetings. I’d also like to thank Jiahai Feng, Vincent Huang, and Alex Gu, some of the friends in question who have worked in AI safety-adjacent areas, for keeping me honest. Opus 5.5 was used for light copyediting of a draft of this article.


[1] See Github repository: https://github.com/openai/math

[2] Press release page: https://openai.com/index/navier-stokes-solution/

[3] See, for example, https://transluce.org/agent-activity

[4] The authors of the manuscript also voice additional thoughts on why AI agents have yet to result in similar breakthroughs on major outstanding problems in physics. The full set of benchmark problems and writeup is available at https://arxiv.org/abs/2610.16733.

[5] The trifecta of learning taken from the excellent https://web.stanford.edu/~aramdas/checklists.html

[6] Although this list was written for students in statistics and machine learning (and includes terms like “HCI”, i.e. human-computer interaction), I think it’s pretty broadly applicable for quantum information too, even if you’re not interested in quantum learning theory. And you might notice that very few points on this list are about learning purely technical skills!

October 16, 2026

Matt von Hippel — Showing Me Your Amateur Breakthrough Is Evidence That It’s Wrong

Ok, people who read my post on the Anthropic science blog: we need to talk.

It’s understandable. You saw me write about AI being used to tackle a serious, publishable physics problem. Naturally, some of you want to share that you accomplished something even more impressive with AI, something the scientific journals and arXiv moderators won’t acknowledge. Maybe you’re hoping I’ll write about it, maybe you want me to check your math. Maybe you just think it’s neat.

But here’s the thing: most of the time, I’m not the right person to send those ideas to. And the fact that you didn’t figure that out is a bad sign.

Outside of the movies, scientists are specialists. Not just “physics” or “particle physics” or “theoretical particle physics”, but so specific that they often focus on particular methods, or are geared around particular goals. For any idea you propose, if it’s good, there will be a small list of people who will be excited to see it and able to evaluate it. They’ll be people who are trying to accomplish the same thing, or people who used the methods you’re using for other things. Those people aren’t hard to find, if your idea is in a field you’re actually interested in: they’re the people who write papers on the subject. If you find the topic interesting, you’ll have read their papers, and know who to reach out to.

So even back when I was active as a physicist, there was only a small list of ideas where I’d be the right person to talk to. Now, though, as I mentioned in the Anthropic post, I’m not a scientist anymore. I haven’t been following the field in enough detail to actually verify anything in detail, even on topics I used to research. Part of the punchline of the post was that I don’t have a clear idea of what’s possible in the field right now. So even if you’ve figured out something in scattering amplitudes, you should reach out to someone who’s still researching the subject, a few of whom were even mentioned in the post!

Now, it might be you’re not interested in someone checking your work, and instead you’re writing to me in my capacity as a science journalist, because you feel like you did something newsworthy. But as a science journalist, I’m not supposed to evaluate your work by myself. I’m supposed to reach out to an independent expert, and if I can’t find any who will speak positively about your result, then the editors won’t publish it. So if you think you did something big enough to merit news coverage, the first thing to do is once again, reach out to a scientist who actually has the expertise to evaluate your work, and get them excited about it. Then you two can contact me together!

If you don’t know who to contact, that’s a sign you don’t read papers in the field. It makes it more likely you managed to convince yourself of something nonsensical, because you don’t have the expertise to evaluate it. It’s a pretty clear sign that I shouldn’t trust you or your AI methods about the result.

It’s also just plain bad for you. If you produce a paper without ever wanting to read any, it suggests your priorities are in a dangerous place: that you’re trying to do something that sounds cool and important over doing something you actually care about.

I’m coming from personal experience here.

As an academic, I spent years telling myself that not enjoying reading papers or going to talks was just part of the job. Then it really cost me something, and I realized the job wasn’t worth my superficial desire to be a physicist. So I left.

Then, I spent a year trying to get a job in industry, and was told the same thing. They wanted to hire people who cared about the job. The finance guys wanted to hire people who read books about finance. The data scientists wanted to hire people who did projects in data science. They wanted, if not passion, then at least grace. Someone who could take to the job easily, and naturally.

Now, what I do for a living is something I was doing once a week, for no more incentive than a vague sense of personal obligation, for over a decade. And I’m doing a lot better.

You want to do something impressive with AI? You think you’re a whiz with Claude Code, that your custom workflow is immune to AI hallucinations?

Then use it for something else. Pick something you actually enjoy reading about, not just the pop news, but the real technical literature. Something you don’t need the AI to explain to you. Something that matters to you, in a way that actually counts.

At the very least, it’ll work out better than writing to me.

Tommaso Dorigo — More on Radiacode 110

More on Radiacode 110

This is the second post reporting a few tests of the Radiacode 110 spectrometer, an extra-cool pocket dosimeter/radiation counter/spectrograph sold by RadiaCode.

Tommaso Dorigo
Categories

October 14, 2026

John Preskill — The Quantum Omelette Problem: How Much Energy Belongs to the Yolk?

The National Egg Coordination Committee created one of India’s longest-running ad campaigns. Its jingle was impossibly catchy. Nearly everyone from my parents’ generation onward seems to remember it:

“Sunday or Monday, eat eggs every day.”

My mum took this advice rather seriously. On weekdays, we ate boiled eggs for breakfast. Sundays, however, were omelette days.

Our ritual was always the same. Each of us siblings announced how many eggs we wanted as we streamed into the kitchen. My mum cracked the eggs into a shiny steel bowl, added our chosen mix-ins, and whisked them together. The yolks, whites, salt, and chili powder quickly disappeared into one speckled mixture. She poured it into a hot, oiled pan, where it hissed and sizzled before sliding onto our plates.

The omelettes were soft, spicy, and gone within minutes.

My diet is now plant-based, but the nostalgia of those Sunday-morning breakfasts remains strong—the steel bowl, the sizzling pan, and all of us gathered around the table, waiting eagerly for the omelettes to arrive.

I couldn’t find a painting that resembled my family around the breakfast table, much less one in the style of an old Mughal miniature. So, for once, I felt compelled to enlist generative AI to fill this rather specific gap in art history.

Our weekday boiled eggs and Sunday omelettes offer a useful contrast. In a boiled egg, the yolk and white remain distinguishable. In an omelette, they are mixed and transformed. Some properties—texture, flavor, and structure—belong to the finished mixture rather than to either component separately.

When two parts interact strongly, which properties still belong to the parts, and which belong only to the whole?

This question appears across science whenever interacting parts become difficult to describe independently. In quantum thermodynamics, it becomes a question of energy. Picture a small quantum system, an atom, say, surrounded by a much larger environment. The total energy of the setup comes from three sources: the atom, the environment, and their interaction.

When the atom barely interacts with its surroundings, separating the energy contributions is easy. The interaction energy is small enough to ignore, and we can speak cleanly of the atom’s energy and the environment’s. When the interaction is strong, however, that shared energy can no longer be brushed aside, making it difficult to decide how much belongs to the atom and how much to its surroundings.

For a large object, interactions with the environment typically occur at the surface, while most of its energy is associated with the much larger bulk. As an object grows, the surface becomes less important compared to its volume, so the interaction energy can often be ignored. But this reasoning breaks down for very small objects, where surface effects remain significant, or for systems whose interactions extend through the bulk, allowing interaction energy to scale with volume.

Such strong interactions are not limited to tiny systems; they also appear across condensed matter, nuclear, and high-energy physics. Lattice gauge theories provide one important example: their particles and fields are tied together by interactions and local constraints, making it especially difficult to draw a clean boundary around one part and declare, “This energy belongs here.”

In all these cases, the energy of the whole may be perfectly clear. The challenge, however, is deciding how to divide that energy among pieces that are no longer truly separate.

That brings us to a deceptively simple question: How should we define the internal energy of a strongly interacting system?

Definitions in physics do more than attach names to things. They tell us what counts as a system, which quantities can be measured, and how mathematical ideas connect to experiments. A useful definition must do more than sound reasonable: it should recover familiar results in familiar situations and remain consistent with the laws of physics. When two plausible definitions lead to different conclusions, the choice between them cannot be settled by language alone.

Consider the internal energy of a system. When a system is strongly coupled to its surroundings, some of the total energy is stored in the interaction, and several reasonable ways of assigning that shared energy become possible. But which definition of internal energy is consistent with thermodynamics? This is the question I explored with my collaborators Zohreh Davoudi, Christopher Jarzynski, Niklas Mueller, Connor Powers, and Nicole Yunger Halpern.

Physicists describe a system’s energy using a mathematical object called a Hamiltonian. In our recent paper, we consider three ways of defining the internal energy of a strongly coupled system.

Definition 1: Subtract the environment
Start with the total energy of the system-environment composite, then subtract the energy the environment would have on its own at the same temperature. Whatever remains, including the interaction energy, is assigned to the system.

Definition 2: Include the environment’s influence
Rather than separating the interaction energy by hand, describe the system’s energy using a modified Hamiltonian that captures how the interaction energy affects the system’s energy at equilibrium. Physicists call this the Hamiltonian of mean force.

Definition 3: Account for temperature as well
The Hamiltonian of mean force depends on temperature. The third definition takes this dependence into account when calculating the system’s internal energy.

All three definitions have appeared in the literature on strong-coupling thermodynamics, each offering a seemingly reasonable way to account for the environment’s influence on the system. We wanted to find out whether choosing one definition over another would change how we describe the same physical process.

To test the three definitions, my collaborators and I considered a sudden quench—the physicist’s term for changing something in the setup almost instantaneously. Imagine rapidly turning a knob that controls the system, perhaps by suddenly switching on a magnetic field. We can also suddenly change how strongly the system interacts with its surroundings, effectively turning the interaction between them on or off. Either change happens so quickly that the system and its environment have no time to respond: their states remain constant during that instant. Yet the system’s internal energy can change because the rules governing it have changed. Since this energy change results from deliberate external control, we call it work.

After the quench, the knob is left alone. The system then evolves under the new, fixed conditions and exchanges energy with its environment. This later change in the system’s internal energy is called heat.

Separating the process into two stages makes it easier to tell work and heat apart: work enters during the sudden, controlled change, while heat flows during the evolution that follows. It is a little like whisking an egg first and then placing it on a hot pan, rather than trying to whisk and cook it at the same time.

Once we have chosen a definition of a system’s internal energy, we can ask how that energy changes during any thermodynamic process. The first law of thermodynamics tells us that the change in internal energy (\Delta U) must be accounted for by work (W) and heat (Q) ,

ΔU=W+Q.\Delta U = W + Q \, .

The first law is essentially a statement of energy conservation. It tells us that any change in the system’s internal energy must be accounted for: the energy must have entered as work, as heat, or as some combination of the two.

But here is the catch. Each of the three definitions of internal energy comes with its own corresponding definitions of work and heat. If we change what we mean by U , we also change how we split that energy change into W and Q . For each of the three choices, however, the definitions are constructed so that work and heat add up to the total change in internal energy. All three therefore satisfy the first law.

At first, this seems reassuring. Perhaps any of the three definitions will do.

To decide whether all three internal energy definitions are truly acceptable, we need a stricter test: the second law. The first law tells us that energy must be conserved, but it does not tell us which direction a process will naturally take. The second law supplies that direction. An egg can be whisked and cooked into an omelette, but an omelette left on the plate will not spontaneously uncook itself, separate into a yolk and a white, and return to its shell. Energy conservation alone would not rule out such a reversal, yet nature overwhelmingly favors one direction. Cooking an omelette is therefore an irreversible process. A perfectly reversible process, by contrast, could be undone without leaving any lasting changes to the system or its surroundings.

A reinterpretation of Salvador Dalí’s The Persistence of Memory (1931) by the Instagram account @chewscagefreeeggs. A playful take on the second law of thermodynamics, irreversibility, and the arrow of time.

For the sudden changes studied in the paper, we can quantify irreversibility by comparing the work actually performed with the minimum work required in an ideal, perfectly reversible process. Thermodynamics captures this minimum through a quantity called the free-energy change, \Delta F ​. The difference between the actual work and this ideal minimum,

W−ΔF,W−\Delta F \, ,

is called dissipated work. It measures the extra work associated with carrying out the process irreversibly, and the second law says that it cannot be negative.

This is where the three definitions part ways. All three satisfy the first law, but only two satisfy the second law for the processes considered in the paper. The third definition, which accounts for the temperature dependence of the Hamiltonian of mean force, can predict negative dissipated work.

Does this mean that our quantum system has somehow broken the second law? Not at all. Rather, the third definition assigns internal energy, work, and heat in a way that makes a valid process look thermodynamically inconsistent.

The next question is why the three definitions agree in classical physics but separate in the quantum case. The answer lies in one of quantum mechanics’ defining features: observables do not always commute. Roughly speaking, when noncommuting observables describe two quantum properties, they cannot both be measured simultaneously. This has no direct counterpart in classical physics, where two observables describing different properties can be measured simultaneously. When the system’s energy and interaction energy cannot be simultaneously measured, the three definitions of work can give three different values.

To explore this connection, we considered what happens when the system’s Hamiltonian commutes with the interaction Hamiltonian, both before and after the sudden quench. In this classical-like limit, all three expressions for work give the same value, which also obeys the second law. In hindsight, the result may seem obvious. Still, there is something oddly satisfying about pinpointing precisely when the three definitions agree: strong coupling alone does not force them to give different answers. Quantum noncommutativity is what allows them to part ways.

Over the years, our family’s egg repertoire expanded. MasterChef episodes, new cookbooks, and travel brought poached eggs, Scotch eggs, shakshuka, eggs-in-purgatory, Tamagoyaki, and plenty of experiments in between. In some dishes, the yolk and white remain almost perfectly distinct; in others, the boundary between them nearly disappears. A whole spectrum exists between separation and complete mixing.

The same is true of a system and its environment: their interaction can range from barely noticeable to overwhelmingly strong. Our results identify two definitions that remain consistent with the laws of thermodynamics for the processes we studied, even when those interactions become strong.

Doug Natelson — Materials-related postdoctoral opportunity at Rice, 2026-2027 edition

See here.
The Rice Advanced Materials Research Institute has launched its 2026-2027 competition for prestigious postdoctoral fellowships - see here:  https://rami.rice.edu/rami-postdoctoral-fellowship-program for details.  The actual application link is here.

If you are interested and meet the criteria, I'd be happy to talk.  I have some ideas that lean into the materials for electronics direction, and other possibilities are welcome.  







October 13, 2026

Scott Aaronson The Mathocalypse

More Updates (Oct. 12): Jeffrey Ketchersid has used Claude Code agents to show that BusyBeaver(10) exceeds Graham’s number, beating the previous best result that BB(13) does so.

In response to my request, a couple days later Jeffrey also used Claude agents to show that the value of BB(335) is independent of ZFC, improving the best previous result from Andrew Wade that BB(393) is. Recall that the first result in this direction, by me and Adam Yedidia a decade ago, only showed an independence result for BB(8000).

Meanwhile, among the many reactions to the mathocalypse, friend-of-the-blog Kunal Marwaha advocates that we become stewards of a “world mathematical commons.”


Updates (Oct. 9): To address some questions that keep coming up…

No, I’m not aware of any direct practical implications of any of these results. I certainly don’t expect the O(n log0.9999999999999 n)-time Fourier Transform algorithm to get practically deployed anytime soon! But anyone who harps on this, simply doesn’t understand what mathematical progress looks like, or how it eventually pulls the rest of science and technology and human civilization with it. If and when the relevant human mathematicians understood the clever new ideas in all 372 of these papers, I have no doubt that they’d be able to use the ideas to do all sorts of new things, and that some of those things would have practical value. That’s yet another reason to try to keep human understanding at the center of our enterprise—unless, of course, you’re happy to outsource the task of understanding and applying the ideas to AI models as well.

Meanwhile, something calling itself the Association for Human Mathematics put out a statement condemning OpenAI for its release. The statement included a sentence that’s since been widely mocked on social media: “Mathematicians did not ask for this work to be done.” (Imagine G. H. Hardy saying to Ramanujan, “who asked you to prove all these bizarre new identities?”)

If it wasn’t clear, the members of AHM speak for themselves, not for the math community as a whole. For my part, I think the math and CS theory communities should absolutely hold the AI companies’ feet to the fire to behave better, both within our little domains, and (much more consequentially) in pacing AI progress, figuring out alignment, and preventing a catastrophe for our whole civilization. So I’m glad that our communities have increasingly been doing that, and I hope to have played a tiny part.

At the same time, I regard the position “no one should spoil our fun by solving our open math problems using AI models” to be totally untenable. It offers no argument for why refraining would be in the broader public interest—as opposed to various mathematicians’ narrow career interests. It violates the core principle that math problems are there for absolutely anyone (yes, even a hated corporation) to try to solve. And of course, it’s not enforceable anyway, in a world where these capabilities will rapidly diffuse to anyone with a GPT or Claude subscription.

We will need to adapt to this new world.


… then they came for Navier–Stokes and I said nothing because I never worked on Navier–Stokes. But when they came for RL vs. L I realized that things are serious

–friend-of-the-blog Omer Reingold (shared with permission)


Last night my 9-year-old son was taunting my wife, complexity theorist Dana Moshkovitz, as follows: “mommy, I heard you got cooked! I heard that a robot solved the math problem you worked on for your whole career! OOF!”

While my son was being a brat, he also wasn’t wrong. Whether you’re thrilled, depressed, angry, or whatever else about it, yesterday was surely one of the biggest days in mathematical history. And yes, among the 372 huge results released yesterday by OpenAI, on the recommendation of its advisory group of Timothy Gowers, Edward Witten, and other distinguished mathematicians, was a proof of Subhash Khot’s Unique Games Conjecture (UGC), a statement that my wife has worked toward proving for the entire time I’ve known her. (The UGC implies that a whole slew of optimization problems really are NP-hard, even if you just want an approximation that’s slightly better than what you get from semidefinite programming relaxation, which is one of our main tools.)

Or at least, we’re pretty sure that it’s a proof! There’s a Lean certificate, as there are for some of the other 372 breakthrough results (not all of them). But it also appears that no human has understood just about any of these proofs yet; the race to do so has just started. If you want an on-the-ground sense of what that race is going to be like, here’s some of what Dana texted me last night:

It feels like something written by someone who’s on psychedelics. So much unclear and doesn’t make sense. Lots of name dropping of previous work without discussing why it can be used despite impossibility results

Basically the paper is so horribly written that it’s impossible to read it without AI help

I asked Astra for reasonable completeness and soundness claims of the noise gadget and it gave them by combining claims from all over the paper

They also have direct optimal NP hardness of approximation proofs for the main applications of the UGC (Max Cut and all CSP) that bypass the UGC.

The UGC proof invents a completely new bizarre code with a noise test. It’s some crazy recursive construction.

It’s not the long code, not the short code – some alien craziness

I still think that there maybe is a proof that uses the half space code (which is natural)

The citations are often irrelevant and confusing

A possible future is a math world that’s heavenly if you have vision/creative ideas that AI could help check and implement.

And of course there’s a lot for us to learn from the aliens

If you’re wondering what emotions Dana is feeling—well, probably all of them! Even while a central career aspiration has fallen to a robot, there are at least two mitigating factors for her. First, she can feel vindicated that the UGC was true after all, something she never doubted even while many of her colleagues did! Second, all of us in math and theoretical computer science and mathematical physics, at least those who cared about solving crisply-stated problems, are now in the same boat.


Besides the Unique Games Conjecture, here’s a small sampling of the treasures from Aladdin’s cave that I’ll probably be paying the most attention to over the coming weeks:

Any of the above, alone, could easily have been “result of the year” in some area (and in some cases, like Unique Games and L=BPL, in all of CS theory). And there’s a lot that I’ve left out—feel free to share in the comments whatever is making your eyes bug out! There are equally astounding wonders in number theory, combinatorics, algebraic geometry, analysis, and pretty much every other area of math, most of which I’ll never understand, although I’ll note that it includes partial progress toward the Riemann hypothesis and the Hodge Conjecture (retracted because of a sign error!) and the Birch-Swinnerton-Dyer Conjecture (i.e., the majority of the remaining Millennium Problems).

We can take solace in what’s missing from the list. P≠NP isn’t there, nor even P=BPP or NEXP⊄P/poly, and surely not for lack of trying. Apparently the greatest open problems of theoretical computer science are indeed pretty hard!


Oh, lest I forget: one day before the OpenAI dump, meaning Monday evening, Virginia Williams and Josh Alman posted an arXiv preprint that solves the 3SUM problem in O(n1.9992) time, and the All-Pairs Shortest Paths problem in O(n2.9995) time, refuting half-century-old conjectures that the correct answers were n2-o(1) and n3-o(1) respectively. In this case, it wasn’t an OpenAI model that supplied the crucial idea; it was an Anthropic one! But Anthropic then took a different approach from OpenAI: rather than post the undigested solutions to the world, it gave Virginia and Josh the opportunity to write and announce a digested version in exchange for compensation.

These have emerged as the two main models for communicating AI math breakthroughs, and they both have strengths and weaknesses. The “OpenAI model” sets up a crazy race among humans to digest and explain a messy AI proof (work that could easily be some combination of thankless, barely-credited, competitive, and unfun), while the “Anthropic model” puts a private company in the position of picking and choosing which human mathematicians get to be the emissaries of the AI. Dunno, what do you guys think?


For those who are wondering: apparently, the AI model that produced all these wonders was not bespoke contraption of 10,000 agents burning millions of dollars worth of compute, as was used for example to construct a finite-time blowup for the Navier-Stokes equations. Instead, it was simply the latest internal OpenAI model—one that might be released to paying ChatGPT customers within the next couple of months, depending on the recommendations of OpenAI’s safety board! (My 9-year-old son: “Oh they definitely shouldn’t release that. If it could solve all those math problems, it can’t possibly be safe.”) Apparently they used about 3 hours of GPT-Pro level compute on average per problem solved.

Also, if you were wondering: apparently they tried the model on about 4,000 problems. So, right now it “merely” solves ~10% of the longstanding open mathematical problems that it’s asked about, the problems that whole communities have spent years on, after a single 3-hour attempt on them. (An earlier version of this post said 8,000 problems and ~5% success rate, but commenters since corrected me.)


I’ve been glad to see the CS theory community rising to the occasion. At the Simons Institute in Berkeley, here at UT Austin, and elsewhere, I’ve hearing stories of researchers rushing to pore over the manuscripts and make sense of them and explain them—because what else do we do? How else do we continue the craft to which we’ve devoted much of our lives?

If you want some sense of what things feel like now in math, imagine a hunter-gatherer who’s spent his entire life learning to survive deep in an unforgiving rainforest, then a giant resort hotel springs up right next to him with a helipad and heated pools and AirBnBs, and without missing a beat, the hunter-gatherer says: “alright fine, so now my new job is to run wilderness retreats for the tourists, or something.”

In Quanta magazine, Jordana Cepelewitz attempted a different metaphor:

It’s as if you were teleported to the peak of a tall mountain. Surrounded by fog, you have no idea where you are, or what’s around you. You do not know how your mountain connects to others, and you have no equipment to help you explore, no way to help someone else join you. If you had climbed the mountain yourself, you would have experienced how the human body adapts to altitude and changes in oxygen levels. You might have had to invent tools to navigate, to climb steep cliffs, or to make a shelter. You might have encountered a fellow explorer, gotten lost together in a hidden valley, and found a plant that could be turned into a life-saving medicine.

Instead you’re perched on the peak but in the dark, while the maker of the teleportation machine tells you that it can explore the wilderness better than any human.

For any one of these mountains, if we care enough, I feel optimistic that we can do as we always have: clear the fog and figure out the path, except now using the teleportation machine to help guide us. The bigger challenge will be to nurture a community that still cares about the heroic adventure of finding the paths up these mountains in the world with the machine. (Oh, and I think one place where the metaphor breaks is that we still do have each other, as much as we ever did before!)


Experience has shown that, even now, there will still be people explaining in patronizing tones why none of this is real and none of it counts. If such people were capable of being impressed by anything that happens in the empirical world, of updating on anything, they would’ve already been impressed and already updated several years ago, long before things had reached the point of an actual Mathocalypse.

So, they’ll say, maybe the alleged solutions are not solutions at all, but just “AI slop.” Or maybe none of the 372 well-known open problems that were solved were real math problems, they were all just glorified contest puzzles and trivialities. (After all, there’s still no Riemann Hypothesis!) Or maybe the entire 4000-year-old discipline of mathematics needs to be jettisoned: turns out that it was all just puzzle-solving and trivialities; all that’s different is that now the triviality stands unmasked. In any case, what really matters is that the true inner sanctum of human creativity hasn’t been breached and probably never will be, and also, that Sam Altman and Dario Amodei are contemptible little nerds.

If you’re still a proponent of that doomed worldview, still aboard the sinking ship, I encourage you in the strongest possible terms to read yesterday’s other great contribution to AI discourse, besides the OpenAI Mathocalypse dump: namely, Scott Alexander’s open letter to Steven Pinker. I feel some responsibility for this, as the person who first introduced Steven Pinker to the existence of the rationalist community, and who also first introduced Steven Pinker and Scott Alexander to one another (they had both been fans of each other’s writing). And now Scott is challenging Steve to a literal duel, with guns!

For whatever it’s worth: Steve is a lifelong intellectual hero of mine, just as he is for Scott, and I also have to privilege of calling Steve my friend. But I found Scott’s post to be one of the most devastating rejoinders to anything that I’ve ever read. And I thought Scott’s conclusion was exactly right: when it comes to AI risk, Steve’s great challenge is now to accept and start using a more “Pinkerite” epistemology.


Last night, while I should’ve been poring over some of OpenAI’s hundreds of papers and/or writing this post, I decided to spend some time with my kids instead. They wanted a movie night, so I suggested something they’d never seen before (and that I hadn’t seen for decades), and that seemed chock-full of no-nonsense, practical guidance for the world in which they’re going to grow up: Terminator 2.


Update: As several people have pointed out, cryptography is a subfield that’s extremely conspicuous by its absence from OpenAI’s list of 376 papers! But my sources tell me that the AI companies have now started, gingerly and discreetly, investigating whether their latest internal models can break important cryptographic protocols and primitives. If they can, then it would certainly be nice to get ahead of things before the rest of the world figures out the same.

Another Update: The statement put out the Advisory Group on Mathematics and Artificial Intelligence is very carefully phrased, neither endorsing nor condemning what OpenAI did, and is worth a read:

As announced a few weeks ago, OpenAI has released a large collection of mathematical results generated by an internal model, reporting solutions to hundreds of open questions. This is an important event for mathematics, with consequences both for mathematics and for the mathematical community that extend far beyond the individual results.

AGMAI’s advisory role should not be interpreted as a judgment of the impact of these results or an endorsement of the process by which OpenAI obtained them. We do not speak on behalf of the entire mathematical community, and only the mathematical community can undertake the assessment that is needed. 

Making this work public is a first step. This release is the beginning, not the completion, of the process of human understanding and the incorporation of the work into mathematical knowledge. At the same time, the future of mathematical research cannot consist only of understanding results produced by AI labs. Mathematicians must be able to formulate their own questions, develop their own approaches, and explore directions that have not been selected as examples of an AI system’s capabilities. Equitable access to powerful research tools and adequate computational resources are essential to that freedom.

We reaffirm our published recommendations on responsible release. We have discussed them with OpenAI and appreciate the company’s willingness to engage. While we consider these discussions constructive, it is ultimately up to the mathematical community to assess the extent to which our recommendations were followed successfully, and whether there are others we should suggest. We remain committed to engaging with any frontier AI lab on these questions and have already been in contact with several of them.

John Baez — Liverworts

I spend a fair amount of time thinking about the climate crisis and how it’s part of a larger collapse of ecosystems, like how insect biomass in Germany has declined by 75% in the last quarter century, how large predatory fish biomass declined by 90% in the last century, how the Amazon is nearing a tipping point where it may cease to be a jungle, and so on.

Did you hear about the UK government report on ecosystem collapse? It was created not only by the environment department but also intelligence agencies like MI5 and MI6. Reporters were invited to see the unveiling of this report in October 2025—but at the last minute the prime minister’s office blocked its release!

Luckily the Greens forced the release of a 14-page redacted version.

𝗧𝗵𝗲 𝗸𝗲𝘆 𝗷𝘂𝗱𝗴𝗲𝗺𝗲𝗻𝘁: 𝗶𝘁 𝗮𝘀𝘀𝗲𝘀𝘀𝗲𝘀 𝘄𝗶𝘁𝗵 𝗵𝗶𝗴𝗵 𝗰𝗼𝗻𝗳𝗶𝗱𝗲𝗻𝗰𝗲 𝘁𝗵𝗮𝘁 𝗲𝘃𝗲𝗿𝘆 𝗰𝗿𝗶𝘁𝗶𝗰𝗮𝗹 𝗲𝗰𝗼𝘀𝘆𝘀𝘁𝗲𝗺 𝗶𝘀 𝗼𝗻 𝗮 𝗽𝗮𝘁𝗵𝘄𝗮𝘆 𝘁𝗼 𝗰𝗼𝗹𝗹𝗮𝗽𝘀𝗲—𝗶𝗿𝗿𝗲𝘃𝗲𝗿𝘀𝗶𝗯𝗹𝗲 𝗹𝗼𝘀𝘀 𝗼𝗳 𝗳𝘂𝗻𝗰𝘁𝗶𝗼𝗻 𝗯𝗲𝘆𝗼𝗻𝗱 𝗿𝗲𝗽𝗮𝗶𝗿.

Thus, I’ve been thinking about life after ecological collapse. Many of the species we love will be extinct. But probably not ferns, mosses and liverworts: ancient plants that have survived many earlier crises.

These were among the first plants to bounce back after the world-wide rain of molten quartz set all the forests on fire when an asteroid hit the Earth 65 million years ago. They were among the first to bounce back after the much worse end-Permian extinction. Liverworts been around for 420 million years, but with bursts of new species beginning in the mid-Jurassic and continuing through the Cenozoic.

The reason these plants can bounced back so fast is that they propagate via spores, not needing to mate with other plants. So, after global crises, we see spore spikes in the fossil record: plants like these become very common, setting the stage for new forests.

So, I’ve been looking at ferns and mosses, which are very common here in Edinburgh because it’s so moist. I knew practically nothing about liverworts, but I was delighted to find a bunch along the River Leith in Edinburgh—shown in my photo here:

Liverworts are so deeply evolved that when you search the internet for info on them, half the articles you’ll see are about how to kill them, because they’re so hard to kill! A small piece of a liverwort can grow into a whole new plant. And some have little cup-shaped structures holding clusters of cells called gemmae. A gemma can be splashed out of one of these cups by falling raindrops, and if it lands in a suitable place it will grow into a new liverwort. It’s as if flakes of your skin splashed off by rain could grow into new copies of you.

So in a bleak time, the world still holds many wonders, and the capacity to regrow.

Tommaso Dorigo — Is Simulation-Based Inference A New Technique In HEP?

Is Simulation-Based Inference A New Technique In HEP?

No, it is not. Please note! It goes back to Stan Ulam in the 1940s!

Tommaso Dorigo
Categories

October 10, 2026

Doug Natelson — Science policy/funding updates, early October edition

This post is a bit later than I'd wanted, due to a combination of work and wanting to be in the right frame of mind to write about what's new in science policy (directly and adjacent matters) and funding.
  • The NSF did underspend their federal appropriation for FY26 by more than 20%, obligating only $6.37B out of more than $8B budgeted.   In terms of numbers of awards, they made 2410 fewer awards in FY26 than in FY25, and about 5000 fewer awards than typical in FY21-24.  
  • This includes the almost complete evisceration of the Social, Behavioral, and Economic Sciences directorate.  As that Science news article points out, SBE has until now funded about 2/3 of all US research in the social sciences (including linguistics and archeology).  The presidential budget request has been calling for SBE's elimination for the last two years.  Congress has rejected that in its budgeting, but seemingly OMB has gotten its way regardless.  
  • There are more NSF X-Labs topics on the way, and a webinar next week to talk more about the "AI for Physical Systems" one.  
  • NSF has also created a "metascience" office and released a statement about collaborating with the UK on this.  I've given my take on metascience before - the idea of seriously studying which types and mechanisms of research funding and programs give the "best" "results" is good in principle, but extraordinarily difficult in practice.  The idea that sound conclusions can be drawn in just a few years is absurd.  
  • On the unambiguously positive side (gotta take the win when there is one), the NSF did announce the surprise support of the National Math Stars effort. 
  • NSF also announced the first of their new Grand Challenge programs, rumored to be a possible destination of (some of?) the unspent funding from the top point above.  No real information about them yet, though the Quantum+X one has a webpage where you can sign up for updates.  Given the description ("Whether you're a researcher at a university, a startup, or an established company, this prize challenge is your chance to help define the next era of quantum technology."), it's hard not to wonder if this is another conscious effort to have NSF be a funding vehicle for industry/business rather than longer-term research.
  • These announcements happened in part at the "Science: A New Golden Age Summit" (link to White House release about this.).  The National Medal of Science was presented to various tech leaders (not scientists).  If any of my readers attended this event, I'd be very curious about a first-hand account.
  • DOE has announced the Genesis Mission Graduate Fellowship program.  The idea is a 4-year PhD with "cocompetencies" between a discipline and AI, with required extended internships at DOE labs/user facilities and industrial partners. The actual call is here, with a LOI due on 9 November and a preproposal deadline of 23 November. 
  • For those of you who are PIs in condensed matter physics, the new DOE notice of funding opportunities (pdf) is out.  Pay close attention to the condensed matter physics program, as its focus has shifted.  
  • Similarly, the new Air Force Office of Scientific Research BAA is out, and as with DOE, the focus of the condensed matter program has shifted.  Both DOE and AFOSR are now explicitly very interested in quantum geometry.  
On the more general research landscape:
  • It's pretty clear that no matter what happens in the upcoming US elections, the next two years at least are likely to be comparatively bleak for federal support of science and engineering research.  Fundamentally, regardless of what OSTP says and despite glossy announcements of new programs, it sure seems like the executive branch (OMB) still wants to curtail federal support for research, and there is not much that even an opposed Congress alone can do in the near term.
  • The number of STEM PhDs entering the job market in 5-ish years is going to be 25% down or more, because funding uncertainty has led to two consecutive years of double-digit decreases in admissions.  Remember, only 10% or less of STEM PhDs go into academia, so this demographic drop is going to be largely felt by industry.  I remain surprised by the apparent apathy about this.  If I thought my technical workforce applicant pool for some jobs might decline by double digits, I'd at least have some concern.
  • Perhaps industry is collectively assuming that AI will somehow make up for this.  OpenAI released 722 preprints out there this week with results in math and mathematical physics.  This is simultaneously impressive and awful, and much has been written about it.  See here for an article and here for a weekly digest, from Quanta.  Peter Woit is hosting an interesting discussion, and points to a collection of comments about this.
  • The US administration also announced a rule change that would impose a $70000 charge for "curricular practical training" (the mechanism that allows international students on F1 visas to have internships during their time as students) and a total of $100000 in fees for "occupational practical training" (the mechanism for international students to be allowed to work in the US for a period after completing their studies).  The actual proposed rule change is here, and people can submit public comments here until November 9.  Personally, I think that this rule change is yet another component of a seeming concerted effort to make the US unattractive as a destination for international scholars, a strategy that is incredibly self-defeating for the country.  (Sure looks like a lot of the "yes, kill OPT" comments are verbatim copy/paste of the same text.  Seems like someone has seen prior public commenting efforts on other controversial rule changes and decided to mobilize.)  Like the prior proposed duration of status changes for F1 and J visas (injunction discussed here), there are likely to be multiple big lawsuits filed over this.  
Whew.  This was a lot.  It's hard to maintain my customary equanimity when the pace of disruptive news is this rapid.  I will hopefully write more about some cool science soon.

October 09, 2026

Matt von Hippel — Congratulations to Francis Halzen!

The 2026 Physics Nobel Prize was awarded this week, going to Francis Halzen for the work that led to the IceCube Neutrino Observatory.

Does that image look weird, like something is missing? It should. This is the first time in over thirty years that the physics Nobel was awarded to just a single person. Most years, it goes to three people, even if they have to awkwardly jam loosely related achievements together to make it work. Some years, it goes to two. The last time one person received the whole prize was 1992.

So why didn’t Halzen have to share the prize like Penrose did in 2020 and Parisi did in 2021? As the saying goes, your guess is as good as mine.

I can say that I was pleasantly surprised to read the announcement and see a name I recognized. I probably couldn’t name the main figures behind most big experiments. If the prize had gone to another founding figure, I’d be out of luck. But I’d heard of Halzen. And specifically, I’d heard about him in the context of the long road it took to get IceCube working.

The IceCube Neutrino Observatory is on the face of it a crazy idea. Neutrinos are almost undetectable, particles that can whiz through a light-year of lead without noticing a thing. To detect them, other experiments had build massive underground tanks of heavy water, shielded from outside interference and covered in cameras, so that on the extremely rare occasions when a neutrino happens to nudge a water molecule, it can be recorded and measured.

IceCube does this on another level, in wild surroundings, by sinking a grid of cameras into a kilometer of Antarctic ice.

So when I saw someone else propose a wild particle detection idea, I talked to my contacts at IceCube, to get an idea of how those wild ideas get fleshed out. And they told me about Halzen.

What they told me, what resonated again and again in Halzen’s writing, and what keeps coming up in quotes from him today, is that it took both luck and persistence. Nature needed to cooperate, there was no guarantee that IceCube would work. But also, the experiment couldn’t have existed without predecessors. He built off plans to put detectors on the bottom of the ocean, and tried out smaller experiments in Greenland.

Those experiments intrigue me, because they filled two roles. On the one hand, they were in a sense mere prototypes, and theorists had strong arguments that they wouldn’t be able to detect anything of interest. On the other hand, those arguments could have been wrong, and the experiments wouldn’t have been made if they could only be justified as prototypes: they were made because there was a chance they could actually see interesting neutrinos.

That combination strikes me as fundamental. We never know, in science, if an experiment will work. So every experiment, deep down, serves this combined purpose. It has to have a chance, even if low and poorly understood, of seeing something new and interesting. And it has to serve as a prototype, to teach us how to make the next experiment. Experiments are almost never one or the other, they are almost always both.

And eventually, as for Halzen, we get lucky, and nature cooperates.

Tommaso Dorigo — The Wondrous Radiacode 110

The Wondrous Radiacode 110

Yesterday I was delighted to receive in my mailbox another radiation spectrometer for testing, the Radiacode 110.

Tommaso Dorigo
Categories

Doug Natelson — NAS "State of Science" 2026 address

I watched the webcast of the NAS State of Science address by outgoing NAS president Dr. Marcia McNutt.  (I did not watch the panel discussion afterward, so sorry if I missed critical pieces.)  A few thoughts on this:
  • The intro music was a very classy baroque string quartet.  Hard not to think of this scene from Titanic.
  • The main theme was about ways to revitalize US science, and there were six main points that she wanted to emphasize, each with examples of relevant projects underway, ways to measure success, and the consequences of failure.  That's fine, and I'll relay them below with some comments, but first an overall impression:  This was largely an exercise in avoiding talking about the elephant in the room, the overt hostility toward and the attempted wanton dismantling of much of the publicly funded US research ecosystem by the executive branch.  I'm unfortunately not surprised that this was largely brushed over, given the position of the Academies (see here).  As the saying goes, I'm not mad, I'm just disappointed.  The realization that the National Academies leadership do not feel empowered to have a frank discussion about this publicly has been depressing.
  • Dr. McNutt mentioned that in her previous address, she had pointed out the US vulnerability in STEM by being so reliant on international talent, and that now that other countries are heavily investing in research, the US STEM research world needs to do a better job getting US citizens in the workforce.  That's all true, but leaving out how the government leadership is explicitly trying to curtail international scholars and international collaboration seems like quite an omission.
  • She mentioned in passing that industrial research in the US in the 1950s was tiny, nothing compared to the fraction of R&D it is today.  Is that actually correct?  I mean, that was the heyday of Bell Labs, IBM, GE, Westinghouse, and big research labs at companies like Ford and GM.  Much has been written about this.  
  • The first big point was the need for improved relationships between universities and industry, and some examples of ways to encourage this, including relatively simple policy changes like making it easier for faculty and others to take leaves in industry.  Certainly it would be broadly good for the US research ecosystem to have more diverse forms of support, and as I've written before, major industrial sectors with lots of capital rely in the long term on trained people. 
  • The second point was the need to realign the academic reward system, so that industrial/entrepreneurial/coalition-building activities are incentivized, rather than rewarding lone-wolf PIs. That's fine, and honestly I think it's already happening to some large degree at major research universities. 
  • The third point was meeting the needs of the STEM workforce, through increased interactions with industry (including, e.g., prospective industrial employers helping to define dissertation topics), co-op efforts, some training in businessy aspects (note:  the Sloan Foundation was pushing this 25 years ago.).  This is all laudable to try, but I don't see how any of this actually addresses the issue of fewer STEM workforce participation from US citizens, which is quite complicated.
  • The fourth point was the need to reduce regulatory burden.  Sure, we all want to reduce bureaucratic BS.  I have to say, though, that it was genuinely baffling to me that the most Dr. McNutt had to say about the threatened OMB rule changes (apart from a passing mention early on) is that they would increase bureaucracy.  That isn't even in the top 15 problems raised by those changes.  Remember, the default position of those pushing those rules is that academics are fundamentally untrustworthy and poor stewards of public resources.  
  • Fifth was the need for automated/self-driving labs.  I agree completely that advanced degree training should not be driven by the need for cheap labor to do tedious lab tasks (e.g. a zillion cell cultures or chemical syntheses).  Overall this was pretty innocuous.
  • Sixth, Dr. McNutt emphasized the need to take on big challenges - researchers need to be bold and not play it safe, and peer review can be inherently biased toward incrementalism.  She gave examples of large privately endowed institutes as enabling such work (MBARI, the Allen Institute).  Apparently STAC will be proposing new multi-agency science and technology "breakthrough funds".  The argument in favor of public investment in science in this section sounded rote rather than heartfelt.  If anything, I thought knocking peer review right now at a time when OMB wants to ignore it at their pleasure was a weird position to take.
To be clear:  I don't think any of the ideas highlighted in the speech are actually bad (necessarily).  It just avoided emphasizing that publicly funded research has been incredibly beneficial, and that irreversible harm is being done.  The statement that science agencies "have seen a loss of key personnel" is the worst kind of passive voice garbage.  A hundred thousand technical personnel leaving agencies is not something that just "happened" like the weather.  Being quiet, avoiding confrontation, and only trying to work behind the scenes is not the leadership that is needed now.  (See, I can do passive voice, too.)

I will try to get back to more science posting....

October 08, 2026

John Preskill — In praise of questions

Prende y se apaga sola,

sale después de hora.

CHARLY GARCÍA

La máquina de ser feliz1

I’ve learned to tolerate them, and sometimes even like them, but Zoom meetings are weird. Even in familiar contexts: I have weekly check-ins with a close friend/collaborator based in Germany, and despite our familiarity, it still feels weird at times. I joined Nicole Yunger Halpern’s group almost when it was established, during Summer of 2021. The pandemic wasn’t exactly over, and most of us were geographically scattered, as well as complete strangers. To half-palliate this awkwardness, Nicole came up with what’s now sort of a group tradition: icebreaker questions. These are chosen by group members (in a secret order that I believe only Nicole fully knows), and can range from day-to-day stuff (“what’s the best type of pasta?”) to deeper matters. 

A while back, a group member asked something along the lines of: “If you could give your younger self any scientific advice, what would it be?” My response then was: “ask the dumb questions you have as they come.” I had two reasons for this answer. First, dumb questions usually sound dumber in your head and are not as bad as you might think. Second, a dumb matter that doesn’t seem dumb at first, can turn into a really, really dumb question if it’s long unanswered. If I were to be asked this same icebreaker question today, I’d surely reply the same thing, but I believe the reasoning would be more nuanced. 

This text’s epigraph comes from a song in the appropriately named album Random, by Charly García. I’m not sure whether the “happiness machine” in Charly’s random scenario deals with Brownian circuits, but I’d like to think so. 

Over my PhD, I’ve had the opportunity to interact, discuss physics, and even collaborate with truly amazing scientists. I still don’t have a foolproof handbook of criteria detailing what makes a great physicist great,2 but I have observed some patterns. An important one is that great physicists speak their mind: they’re usually  relentless with their own confusion and ask whatever they have to ask to overcome it. Don’t get me wrong here; these people are giants, and I wouldn’t dare call their questions dumb, but asking good questions is a skill more than a gift. It’s like seeing Claudia Poll swim or hearing Hilary Hahn play a cadenza: yes, these people are objectively good, but there’s also a huge amount of practice that goes behind what one sees. And, in the case of asking great questions, practice comes from asking not-great (and sometimes even dumb) questions. 

I got a crash course in asking questions during a recent project. A driving theme of my PhD research has been the study of autonomous quantum machines. These devices execute tasks without classical, time-dependent control, operating under a time-independent Hamiltonian. My first experience with these devices was during an experimental collaboration in which Simone Gasparinetti’s group built an autonomous quantum refrigerator from superconducting qubits. The refrigerator ran on a thermal gradient: as heat flowed from a hot bath to a cold one, a three-qubit interaction carried energy out of a target qubit, cooling it with no external control. The experiment was a success, and its potential usefulness in information-processing devices led us to ask about other contexts in which autonomous quantum machines could shine. 

At the time, we came in close contact with folks at Marcus Huber’s group in Vienna, who were thinking in abstract terms about a fully autonomous quantum processing unit. We had the idea of designing autonomous protocols for logical gates in current-day quantum-technology platforms: Rydberg atoms, trapped ions and superconducting qubits.

An autonomous heat engine powers a photon-emitting device (which can be thought of as a clock, for compelling reasons). The photons (ticks) trigger quantum-autonomous gates. 

To illustrate this autonomous-gate idea, I’ll briefly describe a gate protocol from our paper. As I mentioned before, an autonomous quantum fridge can be built by exploiting a thermal gradient. The same principle can help build a heat engine. Suppose one has three qubits, with energy gaps \omega_C, \omega_H and \omega_T. Let’s call these qubits the cold, hot and target qubits, respectively. The cold qubit couples to a bath at temperature T_C and the hot qubit to a bath at a temperature T_H, with T_H>T_C. Under the resonance condition \omega_C+\omega_T = \omega_H, the three qubits can swap energy all at once: the hot qubit loses an excitation while the cold and target qubits each gain one, or vice versa. The gradient makes the first direction more likely. The cold qubit can be engineered to quickly decay to its bath, so the exchange can’t run backward, and the target accumulates excitations. The cold qubit’s energy is lost to its bath, while the target could emit into a waveguide that delivers the photon to a chosen destination. The thermal gradient thus powers a device that emits useful photons with no external control.3 

What can we do with this autonomously emitted photon? We can use it to trigger an entangling gate. Two superconducting qubits with matching energy gaps can exchange excitations. Suppose we  have a tunable-frequency transmon qubit capacitively coupled to a cavity. An incoming photon from our autonomous emitter, entering the cavity, can shift the frequency of the transmon. If this effective, shifted frequency matches a nearby qubit’s frequency, the two transmons can interact. The effect of this interaction depends on the cavity’s decay time, rendering our entangling gate random and potentially useful for the implementation of Brownian circuits, for example. A charming instance of a quantum Rube Goldberg machine, if you ask me. 

An autonomous clock’s tick deposits a photon into a cavity. The photon shifts the frequency of a coupled transmon into resonance with a second qubit, triggering a gate.

This example illustrates the spirit behind our autonomous-gate ideas. As mentioned before, we propose  several more instances over different platforms. This all sounds nice and clean after looking at the end product. But the truth is that, when we started the project, I was a theory student with little knowledge about the inner workings of platforms, trying to pitch convincing arguments for novel gate protocols in these well-established technological fields. I had to go through decades of accumulated literature and famous experiments, trying to understand them and hopefully come up with ways to readapt them to the context of autonomy. Naturally, there were many old papers to read, many small details to understand that were obvious to a familiarized experimentalist but not to me, and, of course, many dumb questions to ask. Regarding this, I have to deeply thank Tom Manovitz, Norbert Linke and Simone Gasparinetti, our experimental collaborators, for their patience with these questions and their willingness to chat and clarify to a confused theorist what’s possible and interesting in experimental contexts. 

Goldberg devised a classical autonomous napkin from a parrot and a clock. We devised a quantum-autonomous gate from an electromagnetic cavity and a clock. Maybe we’re not so different. 

A special mention, however, to postdoc Yuxin Wang. Earlier in the text I mentioned how being relentless with one’s confusion is helpful; she’s one of the clearest examples I can think of. She came into the project right as I was struggling to model one of our superconducting-qubit gates. I was knee-deep in a convoluted formalism, drowning in inefficient numerical simulations that were leading nowhere. She asked a bunch of questions about our system and my modeling attempts for which I had no good answers for, especially because her expertise in both AMO and open systems really made my explanations look weak. I mean this in the best way I can: polishing my arguments and deeply enquiring about modeling decisions forced us to zoom out and look at simpler, more-efficient ways in which we could model our physical setup. I can’t even begin to quantify Yuxin’s patience and helpfulness in the project, nor how much I learned from working closely with her. 

Research, of course, is about asking questions. Trying to clarify confusion and asking in the most transparent way possible are discomforts I still struggle with (much like with Zoom calls), but I’ve learned to appreciate these convoluted scenarios and sometimes even thrive in them. Not being the smartest or most-experienced person in a room has lots of perks. You can learn a lot, although you might need to ask one or two dumb questions to get there. 

  1. It turns on and off by itself,
    it goes out after hours.
    CHARLY GARCÍA
    The happiness machine
    ↩︎
  2.  I do have, however, a handbook of criteria detailing what makes a useful autonomous quantum machine useful, though. ↩︎
  3.  Quantum thermodynamicists call these photon-emitting devices autonomous quantum clocks.  ↩︎

Jordan Ellenberg — When the phone inside your ribcage rings, it’s not for me (They Might Be Giants show report)

Maybe the band I’ve seen play the most times, certainly the band with the biggest time gap between the first time I saw them and the latest (December 1989 to September 2026.) I saw them sometime in the last ten years but I may not have recorded it here; here’s a brief report on the 2009 show, which, like this one, was at the Barrymore, and which, like this one, featured a snippet of “The Famous Polka” (“When the phone inside your ribcage rings, it’s not for me”) as part of another song. They have such a long catalogue now that some of the songs that used to be every-show stalwarts weren’t there; no “Don’t Let’s Start,” no “She’s an Angel,” which may be songs that don’t go well with their current horn-heavy arrangement. (But why not bring back “(She was a) Hotel Detective,” which would sound great with this band?) No “Particle Man”! And they didn’t play the song that got me into the band in the first place, the song that taught me something about how superficial quirkiness can trick you into being defenseless when a song punches you in the face with bottomless sadness. (There’s a lot of this in the early TMBG catalog: “Now it’s either I’m dead and I haven’t done anything that I want / Or I’m still alive and there’s nothing I want to do” — these lyrics are disputed but I’m sticking with my version.) Anyway. Ana Ng and They Might Be Giants and I are getting old, and every five to ten years we walk in the glow of each other’s majestic presence, except for Ana Ng, who is antipodal to all of us, and will remain so, as long as the band still plays.

October 05, 2026

Jordan Ellenberg — Eigenvalues of random p-adic matrices

I always felt there ought to be a good theory of p-adic random matrices paralleling the very-well-worked out real and complex story. I wrote a paper years ago with Jain and Venkatesh that proposed that a very reasonable model for the lambda-invariant of a random quadratic field would be the number of eigenvalues x of a large random matrix A over Z_p such that x-1 is not a unit. (The p-primary part of the class group, the quantity studied in the Cohen-Lenstra conjecture, is modeled by the cokernel of A-1, which is clearly related but not at all the same thing.

Anyway, we worked out a few simple statistics of random matrices over Z_p but got no further. Now Jiahe Shen and Roger van Peski have done much more! They are well on their way to a fully satisfying theory that mimics the archimedean story. For instance, they can exactly compute the pair correlation showing the familiar repulsion of eigenvalues from each other. And the pair correlation function has a somewhat mysterious (to me, and I think to them too) appearance of a theta function…

One reason we like to model arithmetic quantities by random matrices is that, in the function field case, Frobenius acts on etale cohomology via a p-adic matrix we know nothing about, and since we know nothing about it, we like to treat it as random in Haar measure. Is that justified? Maybe not, but here’s the good news: Shen has a followup paper where he shows (again, consistent with what happens in archimedean-land) that the eigenvalue statistics they find don’t depend sensitively on the exact distribution of the matrices, but rather are universal over a rather broad class of distributions. So that, I think, should make one feel more confident that Frobenii, too, have eigenvalues that look this way, and moreover that the analogous distributions in the number field case, where there’s no literal p-adic matrix at all, might follow suit.

The method here is interesting: we learned, over time, that a good way to get a handle on a random group G is to study the expected number of surjections from G to H, as H varies over groups (or groups in various special classes) — these are the natural moments of a distribution on groups. And in practice, they are often the exact statistics one is able to compute by geometric means. (See Will Sawin and Melanie Wood’s work for a much, much, much more elaborated categorical point of view on what counts as a moment.) Shen’s paper takes the view that a good notion of “moment” for a random p-adic polynomial P is the distribution of the p-adic valuation of the resultant of P with some fixed polynomial Z. These “Z-moments” turn out to also be very computable for characteristic polynomials of random matrices, and they also turn out to provide actionable information about eigenvalues. Nice!

Jordan Ellenberg — James Purdy, Narrow Rooms

A great novel if you like murder, sex between men, grudges, West Virginia, and long sentences.

“His eyes were as bright as ever, perhaps brighter, the disc of the pupil appearing to move like a white fire, but his face in general gave the impression of belonging to someone who never expected anything again.”

Purdy’s an unusual writer. Beloved by a few, hated by many reviewers, unknown to almost everyone. Didn’t really start writing until he was 40 (he was a Spanish professor at Lawrence College in Appleton for ten years before that.) Hung out with painters and jazz guys in Chicago. Admired by Langston Hughes and Dame Edith Sitwell, the latter of whom he had his ashes buried next to. Withdrew the rights to the only movie adaptation his work was ever going to get because he didn’t like the proposed lead actor. This reminiscence by Donald Weise gives a vivid picture of the cranky, difficult man.

How did I get into James Purdy? I was in Firestone Library in Princeton, in Special Collections, to see the unpublished J.D. Salinger stories. When I asked for that box, the librarian visibly rolled her eyes, because I think probably 80% of the people who go into Firestone Special Collections are there to see the uncollected Salinger stories. Wounded, crouched, I quickly formulated a way to recoup — I would just request another box, showing that I was not another loser Salinger groupie, but a scholar of mid-century American fiction who was looking at the Salinger in a purely comparative way, setting his unpublished work against that of — well, who? I didn’t know anybody else on the list. So I took a wild guess and asked for the James Purdy box. And then, having taken it, felt compelled to read it. And then, having read it, realized I was in the presence of something a lot better than the stuff Salinger correctly declined to anthologize. I think Purdy would have liked knowing that he’d gotten a reader via a mechanism he cared about a lot and had drawn closely: a young man’s pride and banged-up vanity.

October 04, 2026

Scott Aaronson My new course at UT Austin: AI Alignment Theory

This semester, I’ve been teaching a brand-new course, entitled CS395T AI Alignment Theory. Here’s the course description:

The astounding progress of AI over the past decade has been accompanied by a rising fear: do we really understand how to align and control powerful AI systems—how to get them reliably to do what we wanted, or would want them to do on reflection, rather than merely what we said? If we succeed at building general-purpose superhuman intelligences along the current paradigm, should we expect that development to go well for humanity? Can we modify the design, training, monitoring, or scaffolding of those intelligences to help ensure that it goes well? While there’s been a great deal of recent empirical work touching on these questions, this course will concentrate mainly on theoretical and mathematical foundations. As a warning, the theoretical foundations of AI alignment have not yet gelled into any one coherent body of results accepted as canonical by the field. Nevertheless, in this course, we’ll read and debate many of the conceptual and mathematical works that have been most influential in the AI alignment field, from both before and during the current LLM revolution. Student presentations, reports, and projects will play a central role.

I vividly remember encountering Eliezer Yudkowsky and his Sequences 20 years ago. I remember thinking: even if these people talk and act like crazy cultists, still, let me bend over backwards to be epistemically virtuous, and entertain their ideas on their merits, as very few academics would. Even if, of course, I ultimately end up rejecting the ideas, on the simple ground that powerful AI is such an absurdly remote prospect that it’s almost impossible to say anything useful about it today, outside the realm of speculative fiction.

For my failure to see what was coming, it seems like an appropriate punishment that I’m now, in 2026, effectively teaching a course on Yudkowsky Studies. And it’s the most important course I can teach.

Well, for some definition of “teach.” The thing about AI alignment is that there’s no textbook (though apparently ILIAD is working on one), no core of nontrivial theorems considered canonical by the field, no real body of mathematical theory at all. This makes it extremely different from the courses I’m used to teaching, like Quantum Information Science or Computability and Complexity.

So we’ve been running the course as a discussion seminar. Every session, a “rapporteur” presents an AI alignment research paper or other reading; then I and others ask questions and discuss. Some of the readings (like Omohundro on the “basic AI drives,” or Hadfield-Menell et al. on the off-switch game) predate the current LLM revolution, while others (like the METR report on the HuggingFace incident or Dario Amodei’s “We Must Pace the Frontier”) are so timely that they were only released while the course was underway. Most are somewhere in between.

I expected to have to make a case to students about why AI alignment is a pressing concern, why it’s no longer science fiction, etc. There was huge demand for the course, and while of course there’s a selection effect, the students who’ve shown up have been extremely engaged, sometimes criticizing the assigned papers for not taking existential risk seriously enough.

Perhaps unsurprisingly, we didn’t get that criticism about our very first assigned reading, which was Eliezer Yudkowsky’s 2022 essay AGI Ruin: A List of Lethalities—one the most canonical statements of what Eliezer believes and why that’s shorter than a book. Which brings me to the topic of the rest of this post! Our rapporteurs are not merely presenting the papers in class; they’re also submitting written reports about what the papers said, what their own thoughts were, and what were the highlights of the class discussion. And, with student permission, I’ll be sharing those reports on this blog!

So, without further ado, I present to you our first report, on Eliezer’s list of lethalities, by Tennyson Bardwell, who I thank for his work. Feel free to discuss in the comment section; some of the students might also chime in. Expect more reports here over the coming weeks.


“AGI Ruin: A List of Lethalities” by Eliezer Yudkowsky: Rapporteur Report by Tennyson Bardwell

UT Austin has a new Computer Science course this fall. Alongside familiar graduate-level classes such as Advanced Computer Networks and Convex Optimization sits CS 395T: AI Alignment Theory, taught by Scott Aaronson. This is one of a growing number of AI Alignment courses taught at academic institutions. Just as concerns over catastrophic consequences for misaligned AGI systems reach a broader public discourse, Eliezer Yudkowsky—one of the loudest voices in the field and author of the first assigned reading in Professor Aaronson’s course—is declaring the cause hopeless.

Thus, the students of AI Alignment Theory began their semester by reading a laundry list of critical problems in AI Alignment research, how failure to solve those problems will result in catastrophic consequences, and the reasons to be pessimistic about both past and future progress on these problems. The essay by Eliezer, titled AGI Ruin: A List of Lethalities and posted to his popular community-driven website LessWrong in 2022, is divided into three sections.

Section A roughly describes the magnitude of the AI Alignment problem. That is, the magnitude of the consequences for a complete failure to align an AGI system to human values before construction. It posits that AGI would quickly catch up to all human knowledge simply by learning from existing human productions (colloquially referred to as “eating the internet”) and then, nearly as quickly, begin to meaningfully surpass human knowledge. AlphaGo Zero is presented as a model both for how this might happen, and how it might be difficult to correctly predict beforehand. Many believed that AlphaGo’s success in the board game Go was chiefly attributed to its ability to learn from the extensive history of human-played games. Less than a year after AlphaGo beat the best human player, the successor system AlphaGo Zero surpassed the original AlphaGo. Unlike its predecessor, AlphaGo Zero was trained in just three days by exclusively playing against itself without seeing a single human game.

This quick ramp from AGI to super-intelligence would pose a different sort of problem than humans are generally used to dealing with. Unlike traditional problems in science and engineering, the consequence for a failed attempt might not leave room for another try. An intelligent entity with a misaligned goal would be well aware that it stands in opposition to humans, and might act deceitfully until in a position to act openly against humans without jeopardizing its own survival. Since most goals benefit from control of power and resources, it seems likely that nearly any goal-driven intelligence would have ample opportunity to be misaligned with human desires.

Section B describes reasons why, by default, any AGI that humans build using current methods is likely to be unaligned even if considerable attention is paid to the topic. This “current method” is gradient descent. That is, incremental progress with respect to some loss function which “punishes” a model for undesirable behavior. A notoriously elusive property of such trained models is the ability to generalize out of their training distributions. To train a primitive model to be aligned to humans might involve learning a great many behavioral rules. However, the sorts of rules needed to keep a drastically smarter agent in check might not always be relevant to simpler models (e.g., “do not emotionally dysregulate humans you speak with” might not be relevant to a simpler model that is less able to reliably get under the skin of humans it operates with, or which is assigned tasks in training which do not benefit from such anti-social behavior).

Eliezer focuses on the misalignment of humans with their creators (evolution or evolutionary pressures) as a critical data point for reasoning about misaligned intelligent systems. Despite being a generally slow process, evolution eventually created a runaway intelligent system (Homo sapiens) which proceeded to dominate the globe, decimate related species, and eventually (it is forecasted) effectuate population decline. That last development is arguably in opposition to the sole imperative demanded by evolution: to reproduce.

Section B also makes time for criticism of the most popular paths toward AI alignment, including interpretability (unworkable, and attempting to train on it evokes Goodhart’s law, incentivizing deceit), using multiple AIs to maintain a balance of power (it is not clear how multiple strong AIs unaligned with humanity results in better outcomes for the weak humans), and corrigibility (it seems impossible to motivate an AI system to effect outcomes without also motivating it to desire its own survival to effectuate said outcomes).

Section C describes a bleak state of affairs in which veterans in AI alignment are unsatisfied with current progress and do not have a plan to deliver tangible solutions before the advent of AGI systems. In particular, Eliezer describes recent results as showy but useless. He believes that even with additional funding, the lack of appropriate evaluation mechanisms will prevent the most effective researchers from rising to the top.

A summary of the landscape, as described by Eliezer, in the flowchart below.

Figure 1: A flow chart of (select) paths described by Eliezer in his essay. A common feature of this flow chart is that many “good states”—such as disabling a misbehaving AGI or choosing not to build an AGI—are not “final” states in the sense that they are not permanent solutions. Such a state merely represent the avoidance of a single potential disaster, rather than the emergence of a new stable world state. Hence, these nodes posses back-arrows.

Despite the bleak content, Eliezer’s colorful prose inspired a lively class discussion. Before this discussion started, a survey was taken of the class’s predictions for various outcomes of the AGI in the coming years (with the full results below in figure 2). This survey asked students for their opinion of a number of statements. Each of these individual statement, if true, would reduce concerns of catastrophic AI-driven disasters. For example, when asked “How much do you agree with the statement: Humans will choose to not build AGI” half of respondents said they strongly disagreed with high confidence (agreement = 1, confidence = 5). Students also generally disagreed with the statements:

  • “AGI will not be technically feasible in our lifetime”
  • “(hyper-)AGI will not make extremely obviously unethical decisions”
  • “No reason is individually sufficient, but taken together they provide justification to not fear AGI”

There was a divergence in responses regarding interpretability, corrigibility, and “other” AI alignment research. In the latter two cases, a plurality of respondents (about a quarter) agreed strongly with statements that such research would defang AGI (agreement = 4, confidence=4), while most other responses express various levels of agreement with low confidence. However, when asked about the likelihood of interpretability research defanging AI, the pessimistic voices were more united. A quarter of responses still expressed the same optimism, but roughly half expressed pessimism (agreement ≤ 2) with half of those expressing at least moderate confidence (confidence ≥ 4). Based on the following discussion, this might have been caused by more familiarity with interpretability research, including first-hand experience.

The only statement with general agreement was “(hyper-)AGI will understand human intentions better than we can code it.” However, it should be noted that no statement such as “AGI will respect human desires, as it understand them” was asked on the survey.

Figure 2: Class Survey Results; conducted before a class-wide discussion. Note that students were instructed to answer confidence = 1 when they had not previously considered the statement, to answer confidence = 3 when they felt there were strong arguments on both sides, and to answer confidence = 5 when they possessed well-considered resolve.

After the survey was completed, the results were displayed as an open discussion began. Similar to recent empirical research from frontier labs, interpretability research received more airtime than in Eliezer’s article. Students disagreed first about the definition of interpretability: whether it refers to the ability to interpret a model’s behavior solely by its weights, to interpration via repeated probing of the model in a sandbox, or whether it can also refer to the modern chain-of-thought traces. Regardless of how it was defined, however, participants were either pessimistic or very pessimistic about interpretability research broadly. One student criticized common misunderstandings of chain of thought. Rather than being a verbatim copy of the models internal dialog, it is instead a superficial summary of the complete thought state and routinely produced gibberish, such as rarely used Chinese characters in the middle of otherwise English reasoning.

A popular topic was the exact shape and speed of a recursive self-improvement loop. If it takes place slowly, then what might we learn from “near misses” such as the Hugging Face incident? The number of near misses we are able to learn from before AI possesses sufficient power to prevent further iterations could depend on this curve, with some students arguing that the sheer number of humans, as well as their default robustness in the physical world compared to AI systems means that AI-driven extinction events are still a long way off. Bolstering this “slow take-off” opinion are rumors that AI already plays a major role in model development which could be interpreted as the start of this process.

Some criticized a focus on “solving ethics” as a needlessly high bar that distracts from the more mundane tasks dominating AI alignment work. In particular, the student volunteer who presented this paper (and the author of this report) included a section on “Ethical Dilemmas” in their presentation. Among arguments against focusing on abstract moral philosophy, Professor Aaronson cites Eliezer to emphasize that any alignment at all is difficult, not just in morally gray cases:

When I say that alignment is difficult, I mean that in practice, using the techniques we actually have, “please don’t disassemble literally everyone with probability roughly 1” is an overly large ask that we are not on course to get.

In response, I argue that some examination of everyday decisions with a critical lens—such as telling white lies to loved ones or consuming animal products—can help disabuse us of the notion that goodness emerges in every sufficiently intelligent agent.

One of the most interesting discussions was about the difference between state-of-the-art LLMs and the theorized AI agents long discussed in rationalist discourse. Since current LLMs “mimic the human distribution,” they come preloaded with extensive understanding of human social norms and moral behavior. This makes constitutional alignment (the current practices of using system prompts to establish ground rules) extremely effective. This might either fundamentally change the orthogonality thesis, or provide a new tool to better approximate human judgment in complicated situations.

Of all the points made, the one I found most interesting was simply (paraphrased):

I think human-alignment is just very tractable

Here, “human-alignment” refers not to AI alignment with human values, but cooperation between different humans. More specifically, it refers to the ability for human societies to choose not to rush recklessly into larger-and-larger AI systems. In an academic course focused on the technical problem of AI alignment, this was a reminder to not completely discard policy discussions in the believe that they lack any value. After all, many destructive technologies have been previously contained by international agreements. Notable examples include nuclear weapons and engineered plagues. However, even this was a contentious topic. The main criticisms were (1) the extreme “dual-use” nature of AIs for both peaceful growth and warfare, and (2) the greater danger for AI escapes even after taking precautions to prevent it. However, in the interest of ending on an optimistic note—unlike the assigned reading—it is on this belief in human cooperation that I will leave you.

Doug Natelson — The arXiv - where it's been and where it's going

Back in the ancient mists of time, scientists and mathematicians would circulate preprints of their articles among friends and colleagues via the postal service, as a courtesy, to get feedback and to try to make sure people in the community were aware of their forthcoming work.  As the wikipedia entry says, with the advent of widespread LaTeX and the development of the web, Paul Ginsparg (then at LANL) put together an html-based site for electronic sharing of preprints, initially at xxx.lanl.gov (back before "xxx" in URLs was the kind of thing filtered and blocked by employers).   In 2001 he moved to Cornell, and by then the lab was perhaps relieved to see the site, rebranded as the arXiv, shift to Cornell's library/repository infrastructure.   PIs my age remember (fondly? maybe?) the old days of the arXiv, when Prof. Ginsparg's rather dry sense of humor pervaded the site.  The skull-and-crossbones logo.  The "help"/FAQ pages that basically said, "if you can't figure out how to .tar.gz all of your necessary LaTeX files, and you can't figure out how to make your .eps figures small, maybe you should reconsider whether you're smart enough to be sharing your ideas here".  The arXiv was for preprints, without peer review (though interesting follow-on sites like Scirate now exist for organized commenting on the articles).

From these modest beginnings, the arXiv has grown enormously, including imitators/spin-offs such as chemrxiv and biorXiv and socarXiv.  The arXiv has recently become an independent nonprofit, hired a CEO, secured multiyear philanthropic support, and hosts over 3 million articles.  It's been interesting seeing some level of complaints online about some of these steps, but when the audience is so large, not everyone is going to be happy.  Rapid growth has been a major issue - see here for a graph of monthly submissions:
The exponential rise (except for a slight pandemic-correlated shoulder) has been problematic, especially recently.  One hallmark of the arXiv over the years has been its ability to function with comparatively minimal need for "moderation".  Early on, one consequence of the minimalistic help and moderate technical entry barrier was that it was unusual for fringe/pseudoscience to make its way onto the server.  (Hence the establishment of viXra.)  With the ease of cranking out properly formatted readable manuscripts using AI, clearly the arXiv has been struggling.  If 10-15% of submissions need some kind of human intervention or review, the support needs are rapidly outpacing the limited count of support staff.  There can be substantial backlogs.  To help deal with this, the arXiv recently updated its policies regarding AI-generated content (and AI cannot be a co-author, because the AI tools cannot take responsibility for content), and most recently has had to limit submission rates to two papers per month per submitting author.  These moves, too, have drawn some criticism (e.g. here).  Personally, I think the operators of the arXiv face an incredibly challenging environment and are doing the best they can - the idea that they are making moves because they are establishment sticks in the mud who don't understand the New Way of Doing Science is just wrong-headed.

It's completely unclear where all this is heading.  Exponential growth in nature signals instability and does not continue forever. If proponents of very heavily AI-driven research want to establish a repository specifically for that work, that's up to them.  [It is very on brand for the hard core AI advocates to argue that the arXiv is somehow morally obligated to host everything (regardless of hardware or personnel costs) so that future AI tools can read everything (a repository growing too quickly for human researchers to keep up) and summarize it.]

One overarching point that should come up in any arXiv discussion: The arXiv has become a global repository for an enormous amount of human knowledge, without charging anyone publication fees.  This should make interested parties think reallllllly hard about economic models of for-profit publishers. 


October 02, 2026

Matt von Hippel — Beginnings Don’t Matter as Much as You’d Think

I’ve met people who think they’re uncomfortable with evolution, but when you actually talk to them, they’re worried about something very different. They ask, “How could something come from nothing? How could life come from non-life?”

Biologists aren’t sure of the origin of life. They’re working on it, there’s a whole research field on what the experts call abiogenesis. But it’s hard going, because there’s so little direct evidence.

There is a lot more evidence for evolution. Evolution isn’t a theory of where life comes from, it was never meant to be one. It’s a theory that explains the copious evidence we have from the history of life, from the fossil record to genetic comparisons to leftover features in related animals. It’s a theory that tells you what to expect when you already have some life, and wait a few generations.

Evolution and abiogenesis are different ideas, with different domains. You can have one without the other. And when you already have life, and want to understand it, evolution is quite a bit more useful than abiogenesis.

There’s a similar story with the big bang.

Some people get mystified at the idea that the big bang made something out of nothing. But that’s not really how the big bang works.

It’s not just that the big bang wasn’t the explosion you imagine, a single point expanding in an empty space. Rather, it was a time when the entire universe, everywhere that anything could be, was in a hot dense state, not empty but brim-full.

It’s that the most important part of the big bang is what happened next. As the universe cooled, things spread away from each other, like the residents of Hilbert’s Hotel all moving one room apart. Clumps formed, electrons slowing down and getting caught by protons to make atoms, dust pulling on dust until it collapsed into stars.

The patterns of a universe that cooled this way are distributed over the sky. They tell us the kinds of atoms we expect to see in spectra of stars, the distribution of galaxies, the ripples in the afterglow of the first light to avoid getting absorbed by hot plasma. Those patterns are the core of physical cosmology, the bulk of the field’s research and its strongest argument.

In contrast, the question of where that hot dense state came from is murkier. There are a variety of pictures, different attempts to approximate a context where gravity’s quantum properties should be especially relevant by people who still don’t have a clear idea of how to think about quantum gravity.

But while the question is murky, it’s also just not very useful. Wherever that state came from, knowing it exists is usually enough to chart the rest of the universe’s history. In fact, it may even be impossible for us to know what happened before a certain time: we have only one sky’s worth of evidence, and eventually that evidence runs out.

People are used to created things: food, clothes, cars. Created things don’t change in complicated ways over time, for the most part, just break down. To understand a created thing, understanding its origin matters.

But science is full of stranger things, things with a life, or dynamics, of their own. Natural phenomena change, swiftly becoming something other than what they began as. Understanding them means understanding those changes, much more than it does understanding how they began.

September 29, 2026

Doug Natelson — Annual Nobel speculation thread

 

It's that time of year yet again.  The physics Nobel will be announced next Tuesday, and the chemistry prize on Wednesday.  Who will it be this time?  Please speculate in the comments.  As is my annual futile tradition, I will put forward that the physics prize could be Aharonov and Berry for geometric phases in physics (even though Pancharatnam is intellectually in there and died in 1969).  This is a long shot, as always, especially since last year's prize for “for the discovery of macroscopic quantum mechanical tunnelling and energy quantisation in an electric circuit” was condensed matter related.  Perhaps optical metamaterials, with Yablonovitch, Smith, and Pendry?  (Though that's another one where picking just three names is challenging.)  Astro-related is likely due, so perhaps something CMBR related?

September 25, 2026

n-Category Café Binomial Coefficient Coincidences

These seven equations between binomial coefficients are ‘coincidences’ — they aren’t among the four known infinite families of such equations:

(162)=(103)=120 \binom{16}{2} = \binom{10}{3} = 120

(212)=(104)=210 \binom{21}{2} = \binom{10}{4} = 210

(562)=(223)=1540 \binom{56}{2} = \binom{22}{3} = 1540

(782)=(146)=3003 \binom{78}{2} = \binom{14}{6} = 3003

(1202)=(363)=7140 \binom{120}{2} = \binom{36}{3} = 7140

(1532)=(195)=11628 \binom{153}{2} = \binom{19}{5} = 11628

(2212)=(178)=24310 \binom{221}{2} = \binom{17}{8} = 24310

In 1997, De Weger conjectured that every equation between binomial coefficients follows from the four known systematic equations and the seven coincidences I showed you:

• Benjamin M. M. de Weger, Equal binomial coefficients: some elementary considerations, Journal of Number Theory 63, no. 2 (1997), 373–386.

At that time, he and his collaborators checked there were no others involving binomial coefficients less than 1030. Later they checked that there are none involving binomial coefficients less than 1060:

• Aart Blokhuis, Andries Brouwer and Benne de Weger, Binomial collisions and near collisions.

So, De Weger’s conjecture stands open. The four infinite families, by the way, are these:

(nk) = (nn−k) 0≤k≤n (n0) = 1 n≥0 ((nk)1) = (nk) 0≤k≤n \begin{array}{cccl} \displaystyle{ \binom{n}{k} } &=& \displaystyle{ \binom{n}{n-k} }& \qquad 0 \le k \le n \\ \\ \displaystyle{ \binom{n}{0} } &=& 1 & \qquad n \ge 0 \\ \\ \displaystyle{ \binom{\binom{n}{k}}{1} } &=& \displaystyle{\binom{n}{k}} & \qquad 0 \le k \le n \end{array}

and the only nontrivial one: the Lind–Singmaster family involving the Fibonacci numbers F iF_i where F 0=0,F 1=1F_0 = 0,\ F_1 = 1:

(F 2i+2F 2i+3F 2iF 2i+3)=(F 2i+2F 2i+3−1F 2iF 2i+3+1)i=1,2,3,… \displaystyle{ \binom{F_{2i+2}F_{2i+3}}{\,F_{2i}F_{2i+3}\,} \;=\; \binom{F_{2i+2}F_{2i+3}-1}{\,F_{2i}F_{2i+3}+1} \qquad i = 1,2,3,\dots }

The first three equations in the Lind–Singmaster family are these:

(155) = (146) (10439) = (10340) (714272) = (713273) \begin{array}{ccc} \displaystyle{ \binom{15}{5} } &amp;= &amp;\displaystyle{\binom{14}{6}} \\ \\ \displaystyle{\binom{104}{39} } &amp;= &amp;\displaystyle{\binom{103}{40}} \\ \\ \displaystyle{ \binom{714}{272} } &amp;=&amp; \displaystyle{\binom{713}{273}} \end{array}

When I said De Weger conjectured every equation between binomial coefficients follows from the four known systematic equations and the seven coincidences, I really meant it. For example, the first of the Lind-Singmaster equations combines with the coincidence

(782)=(146)=3003 \binom{78}{2} = \binom{14}{6} = 3003

and other systematic equations to give

(30031) = (782) = (155) = (146) = (30033002) = (7876) = (1510) = (148) \begin{array}{cccccccccc} & \binom{3003}{1} &=& \binom{78}{2} &=& \binom{15}{5} &=& \binom{14}{6} \\ \\ = & \binom{3003}{3002} &=& \binom{78}{76} &=& \binom{15}{10} &=& \binom{14}{8} \end{array}

In fact, if de Weger’s conjecture is true, the number 3003 shows up as a binomial coefficient in more ways than any other positive integer!

I’ll explain the Lind–Singmaster family later. Here’s the question I’m most interested in now:

Is there any good explanation for the seven binomial coefficient coincidences?

My collaborator Paul Schwahn found a beautiful explanation of the first one, namely

(103)=(162) \displaystyle{ \binom{10}{3} = \binom{16}{2} }

His explanation uses representation theory. The Lie algebra 𝔰𝔬(10)\mathfrak{so}(10) has a 10-dimensional representation, the ‘vector’ representation V 10V_{10}, and also two 16-dimensional representations, the ‘left and right-handed spinor’ representations S 10 ±.S^\pm_{10}. There’s an isomorphism of representations

Λ 2S 10 +≅Λ 3V 10 \displaystyle{\Lambda^2 S^+_{10} \cong \Lambda^3 V_{10} }

and similarly for S 10 −,S^-_{10}, but we might as well work with S 10 +.S^+_{10}. Here Λ k\Lambda^k means the kth exterior power. For any vector space XX we have

dim(Λ kX)=(dimXk) \displaystyle{ \dim(\Lambda^k X) = \binom{\dim X}{k} }

Thus, taking dimensions, the isomorphism of representations

Λ 2S 10 +≅Λ 3V 10 \displaystyle{\Lambda^2 S^+_{10} \cong \Lambda^3 V_{10} }

instantly gives

(162)=(103) \displaystyle{ \binom{16}{2} = \binom{10}{3} }

It is not super-easy to prove this isomorphism of representations, but it’s still nice to find a deeper layer of meaning underlying what might otherwise seem like a meaningless coincidence!

Can we find good explanations for the other six coincidences?

First let me explain two failed attempts using representation theory, and then three successes using combinatorics.

Representation theory

First: we can look for isomorphisms like

Λ 2S 10 +≅Λ 3V 10 \displaystyle{\Lambda^2 S^+_{10} \cong \Lambda^3 V_{10} }

involving representations of 𝔰𝔬(n)\mathfrak{so}(n) for larger n.n. In fact this isomorphism is part of a pattern! The next one involves the vector and left-handed spinor representations of 𝔰𝔬(12).\mathfrak{so}(12). But it’s this:

Λ 2S 12 +≅Λ 4V 12⊕Λ 0V 12 \displaystyle{ \Lambda^2 S^+_{12} \cong \Lambda^4 V_{12} \oplus \Lambda^0 V_{12} }

so it gives

(322)=(124)+1 \displaystyle{ \binom{32}{2} = \binom{12}{4} + 1 }

or

496=495+1 \displaystyle{ 496 = 495 + 1 }

So we fail to get an equation between binomial coefficients, but we’re close: we’re only off by one.

The second paper I cited, Binomial collisions and near collisions, presents a list of cases where two binomial coefficients differ by one. This is on the list. So we failed to explain an equation between binomial coefficients, but we explained a near-miss.

Here’s another failed attempt at explaining an equation between binomial coefficients. The equation

(782)=(146)=3003 \displaystyle{ \binom{78}{2} = \binom{14}{6} = 3003 }

is fascinating to anyone who knows their exceptional Lie groups. 78 is the dimension of E 6,\mathrm{E}_6, while 14 is the dimension of G 2.\mathrm{G}_2. G 2\mathrm{G}_2 is a subgroup of E 6\mathrm{E}_6 because G 2\mathrm{G}_2 is the automorphism group of the octonions and E 6\mathrm{E}_6 is the isometry group of the bioctonionic plane. We’d get the above equation if the 2nd exterior power of the adjoint representation of E 6,\mathrm{E}_6, upon being restricted to G 2,\mathrm{G}_2, were isomorphic to the 6th exterior power of the adjoint representation of G 2.\mathrm{G}_2.

Amazingly, it seems these two representations of G 2\mathrm{G}_2 are not isomorphic even though their dimensions are the same: both 3003.

Even more amazingly, E 6\mathrm{E}_6 and G 2\mathrm{G}_2 both have irreducible representations of dimension 3003, but they are not the representations I just mentioned.

I would be happy for someone to check these two claims.

Combinatorics

It turns out that the following three coincidences can all be explained by the same style of combinatorial argument:

(212)=(104),(1532)=(195),(782)=(146) \binom{21}{2} = \binom{10}{4}, \qquad \binom{153}{2} = \binom{19}{5}, \qquad \binom{78}{2} = \binom{14}{6}

The argument is not very elegant, but it’s moderately interesting. Mike Stay got it started by asking ChatGPT, and I finished it off.

In each case the argument has three steps. The first two steps are what combinatorialists call bijective proofs: we prove an equation between numbers by proving a natural isomorphism between structures on sets and then taking cardinalities. The third step is non-bijective because it involves taking an equation and dividing both sides by the same number. Maybe we can make it closer to bijective by using groupoid cardinality, which allows for division, but I haven’t tried that.

Step 1: pairs of edges in a complete graph

Starting from the left-hand binomial coefficient in each equation we’re trying to prove, note that the number on top is a triangular number:

21=(72),153=(182),78=(132) 21 = \binom{7}{2}, \qquad 153 = \binom{18}{2}, \qquad 78 = \binom{13}{2}

Note that ((n2)2)\binom{\binom{n}{2}}{2} counts unordered pairs of distinct edges in the complete graph on nn vertices. Two distinct edges either share a vertex or are disjoint, so there are two cases:

• Sharing a vertex: the pair spans 3 vertices and is determined by this 3-element set together with a choice of which vertex is shared. That gives 3(n3)3\binom{n}{3} pairs.

• Disjoint: the pair spans 4 vertices and is determined by this 4-element set together with one of its 3 splittings into two pairs. That gives 3(n4)3 \binom{n}{4} pairs.

By Pascal’s rule, (n3)+(n4)=(n+14).\binom{n}{3} + \binom{n}{4} = \binom{n+1}{4}. But this also has a bijective proof: add a new point to the set of nn vertices, and a 4-element subset of the enlarged set either contains the new point (so involves a 3-element subset of the old ones) or does not (so involves a 4-element subset of the old ones). Hence we have a bijective proof that

((n2)2)=3(n+14) \binom{\binom{n}{2}}{2} = 3\binom{n+1}{4}

This holds for all n.n. For our three cases we get bijective proofs of the following equations:

(212)=3(84),(1532)=3(194),(782)=3(144). \binom{21}{2} = 3\binom{8}{4}, \qquad \binom{153}{2} = 3\binom{19}{4}, \qquad \binom{78}{2} = 3\binom{14}{4}.

It thus remains to prove

3(84)=(104),3(194)=(195),3(144)=(146). 3\binom{8}{4} = \binom{10}{4}, \qquad 3\binom{19}{4} = \binom{19}{5}, \qquad 3\binom{14}{4} = \binom{14}{6}.

Step 2: a double count

Each of the above equations follows by counting a single set in two ways, and then a nonbijective step: dividing these counts by the same number.

• Showing 3(84)=(104)3\binom{8}{4} = \binom{10}{4}. In a 10-element set, count triples (S,x,y)(S, x, y) in two different ways, where SS is a 4-element subset and x,yx, y are distinct points outside SS. Choosing SS first we see there are (104)⋅6⋅5=30(104) \binom{10}{4} \cdot 6 \cdot 5 = 30\binom{10}{4} triples. Choosing xx and yy first we see there are 10⋅9⋅(84)=90(84) 10 \cdot 9 \cdot \binom{8}{4} = 90\binom{8}{4} triples. So, we get a bijective proof that 90(84)=30(104) 90\binom{8}{4} = 30\binom{10}{4} You can see what we’ll do next.

• Showing 3(194)=(195).3\binom{19}{4} = \binom{19}{5}. In a 19-element set, count pairs A⊂BA \subset B with |A|=4|A| = 4 and |B|=5|B| = 5. On the one hand, there are (194)\binom{19}{4} choices of A,A, and for each there are 15 choices of BB since we can add an extra point in 15 ways. On the other hand, there are (195)\binom{19}{5} choices of B,B, and for each there are 5 choices of AA since we can choose AA in (54)=5\binom{5}{4} = 5 ways. So we get a bijective proof that 15(194)=5(195) 15\binom{19}{4} = 5\binom{19}{5} Again, you can see what we’ll do next!

• Showing 3(144)=(146).3\binom{14}{4} = \binom{14}{6}. In a 14-element set, count pairs A⊂BA \subset B with |A|=4|A| = 4 and |B|=6|B| = 6. On the one hand, there are (144)\binom{14}{4} choices of A,A, and for each there are 45 choices of BB since we can add 2 other points in (102)=45\binom{10}{2} = 45 ways. On the other hand there are (146)\binom{14}{6} choices of BB and for each there are 15 choices of AA since we can choose 4 points in (64)=15\binom{6}{4} = 15 ways. This gives a bijective proof that 45(144)=15(146) 45\binom{14}{4} = 15\binom{14}{6} Again you can see what we’ll do next.

Step 3: division

Having proved

90(84)=30(104),15(194)=5(195),45(144)=15(146) 90\binom{8}{4} = 30\binom{10}{4}, \qquad 15\binom{19}{4} = 5\binom{19}{5}, \quad 45\binom{14}{4} = 15\binom{14}{6}

we can now divide by 30, 5 and 15, respectively, and get

3(84)=(104),3(194)=(195),3(144)=(146) 3 \binom{8}{4} = \binom{10}{4} , \qquad 3 \binom{19}{4} = \binom{19}{5}, \quad 3\binom{14}{4} = \binom{14}{6}

as we wanted, completing our proof that

(212)=(104),(1532)=(195),(782)=(146). \binom{21}{2} = \binom{10}{4}, \qquad \binom{153}{2} = \binom{19}{5}, \qquad \binom{78}{2} = \binom{14}{6}.

I don’t see how to use tricks of the same general sort to explain the remaining coincidences

(562)=(223),(1202)=(363),(2212)=(178). \binom{56}{2} = \binom{22}{3}, \qquad \binom{120}{2} = \binom{36}{3}, \qquad \binom{221}{2} = \binom{17}{8}.

The Lind–Singmaster family

Lind and Singmaster were trying to find all n,kn,k with

(nk)=(n−1k+1) \displaystyle{ \binom{n}{k} = \binom{n-1}{k+1} }

I’ll rapidly sketch the key steps of their argument. Simplifying the equation above we get

n(k+1)=(n−k)(n−k−1) n(k+1) = (n-k)(n-k-1)

or

n 2−(3k+2)n+(k 2+k)=0 n^2 - (3k+2)n + (k^2+k) = 0

Solve for nn using the quadratic formula. This formula turns out to have

5k 2+8k+4 \sqrt{5k^2 +8k+4}

in it. So we need 5k 2+8k+45k^2 +8k+4 to be a perfect square!

Now we’re trying to find integer solutions of

5k 2+8k+4=m 2 5k^2+8k+4 = m^2

A quadratic diophantine equation! Multiply by 5 and complete the square:

5m 2=(5k+4) 2+4 5m^2 = (5k+4)^2 + 4

y=5k+4y = 5k+4 is an integer when kk is, so we need to find integer solutions of

y 2−5m 2=−4 y^2 - 5m^2 = -4

This is a ‘Pell equation’, and people know how to solve these. In this particular case we get all the solutions from this fact:

L n 2−5F n 2=4(−1) n L_n^2 - 5F_n^2 = 4(-1)^n

where F nF_n are the Fibonacci numbers 0, 1, 1, 2, 3, … and L nL_n are the Lucas numbers 2, 1, 3, 4, 7, …. These are two sequences satisfying the same famous recurrence relation, just with different initial conditions.

We want nn odd, to get

L n 2−5F n 2=−4 L_n^2 - 5F_n^2 = -4

It turns out y=L n,m=F ny = L_n, m = F_n with nn odd give all solutions of the Pell equation

y 2−5m 2=−4 y^2 - 5m^2 = -4

However, remember I said y=5k+4y = 5k+4 is an integer when kk is. But the converse isn’t always true, and we need kk to be an integer! This clearly happens iff y≡4bmod5.y \equiv 4 \bmod 5.

So we need to know when L n≡4bmod5L_n \equiv 4 \bmod 5 Apparently this happens iff n≡3bmod4.n \equiv 3 \bmod 4. I won’t think about this now… but this is the last hard step.

In summary, we’ve seen

(nk)=(n−1k+1) \displaystyle{ \binom{n}{k} = \binom{n-1}{k+1} }

if and only if y=5k+4y = 5k+4 is a Lucas number L nL_n with n≡3bmod4.n \equiv 3 \bmod 4. We could quit here, but people like to use the identity

L 4i+3−4=5F 2iF 2i+3 L_{4i+3} - 4 = 5F_{2i} F_{2i+3}

to get a formula for kk in terms of Fibonacci numbers. This is gilding the lily, I’d say, but it eventually leads to the formula that de Weger presents:

(F 2i+2F 2i+3F 2iF 2i+3)=(F 2i+2F 2i+3−1F 2iF 2i+3+1),i=1,2,3,… \displaystyle{ \binom{F_{2i+2}F_{2i+3}}{\,F_{2i}F_{2i+3}\,} \;=\; \binom{F_{2i+2}F_{2i+3}-1}{\,F_{2i}F_{2i+3}+1\,}, \qquad i = 1,2,3,\dots }

The takeaway message is: our problem can easily be reduced to a quadratic diophantine equation, then put in Pell form… and it’s known that the sequence of integer solutions of a Pell equation obeys a linear recurrence relation! We luck out in this case and get solutions connected to Lucas and Fibonacci numbers.

It’s probably a lot easier to show that the Lind–Singmaster equations hold. The above argument does a lot more, by showing that every equation of the form

(nk)=(n−1k+1) \displaystyle{ \binom{n}{k} = \binom{n-1}{k+1} }

is in the Lind–Singmaster family. De Weger gets into a lot more number theory trying to rule out various other kinds of coincidences between binomial coefficients. It’s downright scary how these questions pull you into the deep, icy waters of mathematics.

Matt von Hippel — It Got to My Field

For the folks who found this blog from Anthropic’s site, welcome!

For everyone else, I’d better give some context.

Last month, I had a blog post titled “It Only Counts When AI Gets to My Field”. The title was a joke, the content less so. I said that if some of the longstanding problems of my old research field got solved by AI, then I’d sit up and take notice.

The post turned out to be a bit of a self-fulfilling prophecy, after some folks at Anthropic read it and decided to tackle one of the outstanding problems I mentioned. They then invited me to write a post about it on their science blog.

The post is here. I recommend reading it, then coming back. The rest of this post will be a little Q&A.

Q: At the end of that post, it says Anthropic paid you for your time. Can we trust what you wrote?

A: When I agreed to write the post, I made it clear that I was going to give my own opinion, not write an ad for Anthropic. They could propose light edits, but that’s it. And I avoided signing anything with them, not even an NDA, so I could freely tell you if they pushed my boundaries.

They didn’t push my boundaries. They asked me to clarify a few things, and to give more detail on the science. I didn’t change the message or the takeaways.

The reason I asked them to pay me is that, as a freelance writer, I don’t have a salary to fall back on. Time I spend on a project like that post is time I’m not spending on journalistic projects, so if I worked on it for free I’d essentially be using my vacation time for it. The rate I’m charging them is roughly in the middle of what I’d have gotten paid if I used that time on journalism: a bit more than I would have made working for the lower-paying outlets, a bit less than I would have made with the higher-paying ones.

I’m also not expecting this to be the start of a longer-term business relationship or anything like that. So overall, I don’t think I’m incentivized to lie on their behalf. You can trust me.

Q: How confident are you that they did what they said they did?

A: I didn’t get the feeling they were lying. But I didn’t start out skeptical.

I haven’t seen the logs from the LLM, or anything like that. That’s the kind of thing I would dig into if I were more suspicious of their story. If there’s a reason to be suspicious, I’ll ask.

But so far, I don’t feel that I have much reason to be suspicious. They were able to look up details on the fly when I asked them, they didn’t seem to have a polished message they were trying to push past me. And more importantly, as I’ll mention in a bit, I don’t think anything they described is all that outlandish. It lines up, largely, with the capabilities I’d expect their Claude Science platform to have.

It’s also relevant that they didn’t use an internal model for this. It means that scientists will likely be trying out similar problems soon, so if it does turn out they exaggerated something, people are going to figure out quite quickly.

Q: So how big is this? We just saw AI solve a Millennium problem, after all.

A: This was a lot easier than a Millennium problem. But it was also a lot cheaper.

The problem they solved is one with a clear recipe, honed and explained over multiple papers. It’s something I expected to be hard to do without access to a lot of computer power, so I thought it would need to be approached with a novel technique, in order to avoid using that computer power.

In the end, it didn’t need that. As I mention in the post, another group got most of the result at around the same time, with a much smaller amount of AI assistance.

It’s not an easy recipe, to be clear. I think other people will be surprised that a reasonably affordable program like Claude Science can do this without a lot of guidance. I’m not surprised, mostly, because I’ve been paying enough attention to what people have been doing with these things, and carrying out this kind of recipe consistently is actually something the good science AIs can do right now. If you haven’t been following as closely, that’s going to be a lot more surprising.

So maybe the best way to answer this is: instead of paying $15 million to solve one of the most famous problems in mathematics, they paid $1,000 or so to make a significant next step in an ongoing research program in theoretical physics. This doesn’t tell you much about whether AI can achieve field-defining breakthroughs, but it tells you a lot about the kinds of things a theoretical physicist with $1000 spare budget can do right now.

(As an aside, it feels crazy to me that 90% or more of the compute cost was from the LLM, not the calculation itself. On the one hand, it feels nuts to essentially use ten times more computer power to do this than would have been needed if a human had done the coding. On the other hand, I’ve applied for grants that budgeted more than that per year for travel costs, and spending this kind of money on getting a result seems a lot more useful than spending it on airfare.)

Q: Isn’t it reckless to publicly post a problem for AI like that?

A: I posted my challenge before OpenAI announced their Navier-Stokes result. At that point, there had been a few awkward surprises, but for the most part AI companies had a pattern of talking to an academic first before trying to solve a problem. It’s what they did back in March.

I expected that was what they’d do this time, and got more than a little blindsided when they just solved the problem on their own and reached out to Lance afterwards. I’m lucky that Lance doesn’t seem mad at me about it, it would have been quite understandable if he was.

I did tell them that if they wanted to tackle any of the other problems in that post, they should reach out to one of the scientists involved first, before attempting it. In addition to being polite, it’s a way to make sure that they understand the problem correctly and have a plan to verify the result. They happened to pick a challenge that was particularly easy to verify, but it didn’t have to go that way.

Q: Any thoughts about AI’s future impact on science?

A: If there’s a problem you can’t solve, but you think someone with expertise in another field or better programming skills could, then it’s probably solvable with AI.

A lot of problems don’t fall into that category. I’ve seen people talking online about AI solving quantum gravity, but solving quantum gravity is a question of which bullets you’re willing to bite, not a question of technical skill. That doesn’t mean AI will never be able to address it, but if so it will come from some sort of superpersuader aspect, not merely scientific capabilities.

And of course, some fields do require experiments. People are increasingly building AI-powered labs. I’ll leave it to people from actual experimental fields to think about the potential there.

Q: Can you say something explicit about the bigger risks from AI, now?

A: As I mention in the post, I didn’t learn that much about the bigger questions from this. I’m still not an expert.

But there’s one thing I think is worth emphasizing:

This technology is clearly getting more effective over time. I don’t think they could have done this six months ago. If you’re trying to predict what will happen next, you shouldn’t just assume this is the most powerful it will get, or the cheapest. If you think there’s a limit, you need to argue for it.

Edit: One more thing I should mention, now that I’ve confirmed she’s ok with it: the idea for my challenge came from some discussions at Lancefest, a conference in honor of Lance back in June, and particularly from Anastasia Volovich, whose talk declared the nine-loop calculation “a benchmark – or a ‘challenge’ – against which any “AI takeover” should be measured”.

September 24, 2026

John Baez — Binomial Coefficient Coincidences

These seven equations between binomial coefficients are ‘coincidences’: they aren’t among the four known infinite families. De Weger conjectured that there are no more such coincidences:

• Benjamin M. M. de Weger, Equal binomial coefficients: some elementary considerations, Journal of Number Theory 63, no. 2 (1997), 373–386.

At that time, he and his collaborators checked there were no others involving binomial coefficients less than 1030. Later they checked that there are none involving binomial coefficients less than 1060:

• Aart Blokhuis, Andries Brouwer and Benne de Weger, Binomial collisions and near collisions.

So, De Weger’s conjecture stands open. The four infinite families, by the way, are these:

\displaystyle{ \binom{n}{k} = \binom{n}{\,n-k\,}, \qquad 0 \le k \le n}

\displaystyle{ \binom{n}{0} = 1, \qquad n \ge 0 }

\displaystyle{ \binom{\binom{n}{k}}{1} = \binom{n}{k}, \qquad \qquad 0 \le k \le n}

and the only nontrivial one: the Lind–Singmaster family involving the Fibonacci numbers F_i where F_0 = 0,\ F_1 = 1:

\displaystyle{    \binom{F_{2i+2}F_{2i+3}}{\,F_{2i}F_{2i+3}\,}    \;=\;    \binom{F_{2i+2}F_{2i+3}-1}{\,F_{2i}F_{2i+3}+1\,},    \qquad i = 1,2,3,\dots }

The first three equations in the Lind–Singmaster family are these:

\begin{array}{ccc}   \displaystyle{ \binom{15}{5} }  &= &\displaystyle{\binom{14}{6}}   \\ \\    \displaystyle{\binom{104}{39} } &= &\displaystyle{\binom{103}{40}} \\ \\    \displaystyle{ \binom{714}{272} } &=& \displaystyle{\binom{713}{273}}  \end{array}

I’ll explain the Lind–Singmaster family later. But here’s the question I’m most interested in:

Is there any good explanation for the seven binomial coefficient coincidences?

Today my collaborator Paul Schwahn found a beautiful explanation of the first one, namely

\displaystyle{ \binom{10}{3} = \binom{16}{2} }

His explanation uses representation theory. The Lie algebra \mathfrak{so}(10) has a 10-dimensional representation, the ‘vector’ representation V_{10}, and also two 16-dimensional representations, the ‘left and right-handed spinor’ representations S^\pm_{10}. There’s an isomorphism of representations

\displaystyle{\Lambda^2 S^+_{10} \cong \Lambda^3 V_{10}   }

and similarly for S^-_{10}, but we might as well work with S^+_{10}. Here \Lambda^k means the kth exterior power. For any vector space X we have

\displaystyle{ \dim(\Lambda^k X) = \binom{\dim X}{k}  }

Thus, taking dimensions, the isomorphism of representations

\displaystyle{\Lambda^2 S^+_{10} \cong \Lambda^3 V_{10}   }

instantly gives

\displaystyle{  \binom{16}{2} = \binom{10}{3} }

It is not super-easy to prove this isomorphism of representations, but it’s still nice to find a deeper layer of meaning underlying what might otherwise seem like a meaningless coincidence!

Can we find representation-theoretic explanations—or other explanations—for the other six coincidences?

I have not succeeded, but let me tell you about two failed tries.

We can look for isomorphisms like

\displaystyle{\Lambda^2 S^+_{10} \cong \Lambda^3 V_{10}   }

involving representations of \mathfrak{so}(n) for larger n. In fact this isomorphism is part of a pattern! The next one involves the vector and left-handed spinor representations of \mathfrak{so}(12). But it’s this:

\displaystyle{ \Lambda^2 S^+_{12} \cong \Lambda^4 V_{12} \oplus \Lambda^0 V_{12}  }

so it gives

\displaystyle{ \binom{32}{2} = \binom{12}{4} + 1  }

or

\displaystyle{ 496 = 495 + 1 }

So we fail to get an equation between binomial coefficients: we’re off by one.

The second paper I cited, Binomial collisions and near collisions, presents a list of cases where two binomial coefficients differ by one. This is on the list. So we failed to explain an equation between binomial coefficients, but explained a near-miss.

Here’s another failed attempt at explaining an equation between binomial coefficients. The equation

\displaystyle{  \binom{78}{2} = \binom{14}{6} = 3003 }

is fascinating to anyone who knows their exceptional Lie groups. 78 is the dimension of \mathrm{E}_6, while 14 is the dimension of \mathrm{G}_2. \mathrm{G}_2 is a subgroup of \mathrm{E}_6 because \mathrm{G}_2 is the automorphism group of the octonions and \mathrm{E}_6 is the isometry group of the bioctonionic plane. We’d get the above equation if the 2nd exterior power of the adjoint representation of \mathrm{E}_6, upon being restricted to \mathrm{G}_2, were isomorphic to the 6th exterior power of the adjoint representation of \mathrm{G}_2.

Amazingly, it seems these two representations of \mathrm{G}_2 are not isomorphic even though their dimensions are the same: both 3003.

Even more amazingly, \mathrm{E}_6 and \mathrm{G}_2 both have irreducible representations of dimension 3003, but they are not the representations I just mentioned.

I would be happy for someone to check these two claims.

If anyone knows good explanations of the remaining six binomial coefficient coincidences, please let me know!

The Lind–Singmaster family

Lind and Singmaster were trying to find all n,k with

\displaystyle{ \binom{n}{k} = \binom{n-1}{k+1} }

I’ll rapidly sketch the key steps of their argument. Simplifying the equation above we get

n(k+1) = (n-k)(n-k-1)

or

n^2 - (3k+2)n + (k^2+k) = 0

Solve for n using the quadratic formula. This formula turns out to have

\sqrt{5k^2 +8k+4}

in it. So we need 5k^2 +8k+4 to be a perfect square!

Now we’re trying to find integer solutions of

5k^2+8k+4 = m^2

A quadratic diophantine equation! Multiply by 5 and complete the square:

5m^2 = (5k+4)^2 + 4

y = 5k+4 is an integer when k is, so we need to find integer solutions of

y^2 - 5m^2 = -4

This is a ‘Pell equation’, and people know how to solve these. In this particular case we get all the solutions from this fact:

L_n^2 - 5F_n^2 = 4(-1)^n

where F_n are the Fibonacci numbers 0, 1, 1, 2, 3, … and L_n are the Lucas numbers 2, 1, 3, 4, 7, …. These are two sequences satisfying the same famous recurrence relation, just with different initial conditions.

We want n odd, to get

L_n^2 - 5F_n^2 = -4

It turns out y = L_n, m = F_n with n odd give all solutions of the Pell equation

y^2 - 5m^2 = -4

However, remember I said y = 5k+4 is an integer when k is. But the converse isn’t always true, and we need k to be an integer! This clearly happens iff y \equiv 4 \bmod 5.

So we need to know when L_n \equiv 4 \bmod 5 Apparently this happens iff n \equiv 3 \bmod 4. I won’t think about this now… but this is the last hard step.

In summary, we’ve seen

\displaystyle{ \binom{n}{k} = \binom{n-1}{k+1} }

if and only if y = 5k+4 is a Lucas number L_n with n \equiv 3 \bmod 4. We could quit here, but people like to use the identity

L_{4i+3} - 4 = 5F_{2i} F_{2i+3}

to get a formula for k in terms of Fibonacci numbers. This is gilding the lily, I’d say, but that eventually leads to the formula I showed you:

\displaystyle{    \binom{F_{2i+2}F_{2i+3}}{\,F_{2i}F_{2i+3}\,}    \;=\;    \binom{F_{2i+2}F_{2i+3}-1}{\,F_{2i}F_{2i+3}+1\,},    \qquad i = 1,2,3,\dots }

The takeaway message is: our problem can easily be reduced to a quadratic diophantine equation, then put in Pell form… and it’s known that the sequence of integer solutions of a Pell equation obeys a linear recurrence relation! We luck out in this case and get solutions connected to Lucas and Fibonacci numbers.

There may be a simpler argument, but this is what I’ve seen.

September 17, 2026

Tim Gowers — Why I didn’t sign the Fields medallists’ letter

[This post has been cross-posted to Terence Tao’s blog.]

When I was around 11 I heard for the first time about Fermat’s Last Theorem. I was immediately captivated by the problem statement, as well as by the accompanying story, and made a fairly serious attempt to prove it. And while, unsurprisingly, I failed, I learned a lot from the attempt. Blissfully ignorant of the fact that the n=3 case had been proved by Euler over 200 years earlier, I decided that that would be a good place to start: once I had sorted that out, I was optimistic that I would be ready to tackle the general case.

Since I still couldn’t really see where to start, I decided to simplify the problem further and concentrate on successive differences of cubes, with a view to showing that such a difference could not itself be a cube. At the time I did not know how to express what I was doing in algebraic language, so I did not explicitly try to prove that the Diophantine equation 3n^2+3n+1=m^3 had no solution. Rather, I just worked out some successive differences and stared at them, trying to get some idea of why none of them was a perfect cube. (I should be clear that this story is a reconstruction of what I think probably happened given the few memory traces that remain half a century later rather than a completely reliable account.) At some point, I had the idea of taking the difference sequence of the difference sequence, and discovered that it formed an arithmetic progression. That felt like progress, so I investigated difference sequences a bit more and discovered, purely empirically, the rule that if you start with nth powers and keep taking successive differences, then eventually you get to the constant sequence n!, n!, n!, \dots.

Somehow I never managed to turn this observation into a proof of Fermat’s Last Theorem, and later on my dream of solving it got replaced by other mathematical dreams. However, when I reached the point in my mathematical education where I was taught about taking difference sequences and about what happened to polynomials, I understood those topics much better than I would have if I had not discovered difference sequences for myself and spent happy hours playing around with them. I mention this story just as an illustration of the phenomenon that was strongly emphasized in this letter signed by 25 Fields medallists, that one learns a lot from thinking about a problem, regardless of whether one solves it.

In the end, however, I felt that I could not sign the letter, despite agreeing with much of what it said. Instead, it seemed better to do what I did with the Leiden Declaration and set out my own position in a blog post. But it should be understood that by doing that I am not setting myself up as a member of some opposing camp: indeed one of my worries at the moment is that the mathematical community might become bitterly divided, something I would very much like to avoid. Also, I agree on the fundamental point that we are facing a crisis: I just want to offer a slightly different analysis of what that crisis is. I don’t claim full originality for this analysis, as I know that several other mathematicians have already put forward thoughts that are similar to the ones I have, though (for what it’s worth) I have largely come to these conclusions independently.

On the subject of independence, it will perhaps help if I clarify that while I have contacts in the mathematics group at OpenAI, and have also been given early access to some of their models (typically only a few days before they have been released), and have been given free access to their Pro models once released, I have never been paid by OpenAI. I mention this in the hope, perhaps naive, that what I write will not be dismissed for ad hominem reasons. Another potential reason for my being regarded as “pro-AI” is that, as I have stated publicly several times, I have a group in Cambridge devoted to automatic theorem proving. However, that is actually more of a reason to be anti-AI, since our group has been trying to attack the problem of getting computers to prove interesting theorems by understanding as well as possible how humans prove interesting theorems, so now that LLMs can clearly do it without the help of such insights as we have had, one of the main motivations for our work has disappeared. To put it another way, we have had to swallow the bitter lesson (which of course we were always aware was a distinct possibility, even if the speed at which it happened has taken us by surprise). I do in fact think that it is still a very interesting and valuable intellectual exercise to try to gain this understanding, even if we can use LLMs as black boxes, but that’s a topic for another blog post.

So why didn’t I sign the letter? Let me extract a couple of sentences from it that express what I see as the principal argument being put forward.

But solving problems is only a tool and proxy for achieving the primary goal of conceptual understanding and insight. Forgetting this in the world of AI may turn the tool against the primary goal. Indeed, the mass production at faster and faster pace of “true/false” statements could destroy fertile ground instead of breathing life into new ideas.

Perhaps the main reason I didn’t sign is that I don’t fully subscribe to this view. Instead, I have a more complicated view, which I actually expressed in my essay The Two Cultures of Mathematics a quarter of a century ago, and which can be summarized by saying that there is a spectrum of attitudes in mathematics to the relationship between problem-solving and conceptual understanding. At one end of the spectrum you have mathematicians who are primarily motivated by the wish to solve problems, who see conceptual understanding as a very important means to that end. At the other you have mathematicians who are primarily motivated by the wish to attain conceptual understanding, who see problem-solving as a very important means to that end. I worry that the severe-misalignment letter could be seen as saying that the “right” attitude is to focus on conceptual understanding as the main priority — indeed, the above sentences say that more or less directly. But I think that there are mathematicians all across the spectrum, and that that is a good thing (or perhaps I should say that it has been a good thing up to now — the future is much less certain), and I don’t want to suggest to a large fraction of mathematicians, including myself, that their mathematical temperament is somehow “wrong”.

My own particular mathematical attitude is very similar to one that was beautifully articulated in a Twitter post by Jacob Tsimerman (another non-signatory of the letter), which, now that I look at it, says a lot of what I will be saying here. And that post in turn is a response to Daniel Litt, who is in my opinion one of the wisest commentators on mathematics and AI. His views are expressed in a later post here, which I deliberately didn’t read until finishing this one, and then found, as I expected, that there was significant overlap. I would also like to take this opportunity to recommend an excellent post by Noah Smith entitled The End of the Age of Heroes, in case you haven’t read it.

I have been talking so far about individual mathematical understanding, but I suspect that what concerns most of the signatories is less that than the collective understanding that results at least in part from the human activity of problem solving. My guess is that they would argue, completely coherently, that even if collective understanding is the primary goal, if many individuals are primarily motivated by the wish to solve problems, that’s absolutely fine and contributes to that collective understanding.

With that interpretation, the issue becomes slightly different: is it more important that the collective understanding of the mathematical community should be as advanced as possible or that there should be answers to as many problems as possible? Or are those two aims valuable in different ways, so that there is no point in declaring one of them more important? Or are they so inextricably linked that it makes no sense to argue that one is more important than the other? And when we say “important”, for whom are we saying it is important: for mathematicians, or for society as a whole?

I find these hard questions, so I don’t want just to declare an answer to them. (Do you see what I did there?) Instead, I’d like to try to offer at least some argument for any conclusions I come to, even if they are tentative. So let’s compare two scenarios. In the first, which I think is the more likely actually to happen, models become publicly available that are better at solving problems than virtually all mathematicians. If there are a few residual mathematicians who can do things the models can’t, even they work far faster if they make heavy use of the models. Thanks to this, in a short time we get answers to many questions that we have deeply cared about, but the rate at which we receive these answers far exceeds the rate at which the mathematical community can absorb them. In particular, most of the answers are obtained with zero effort from human mathematicians — just prompts such as “Thank you — please continue”.

In the second scenario, there has been an international agreement, for entirely other reasons, to block the public release of models significantly more powerful than the ones we currently have, and the mathematicians within the tech companies agree to hold off from getting their internal models to solve major problems. Instead, they take guidance from the mathematical community, solving problems only when asked to do so by some suitably representative body that decides that the benefit of receiving a solution of a certain problem outweighs the benefits of humans struggling to solve it over a much longer timescale.

I’d like to consider what the difference would be between these two scenarios both for individual and collective understanding. I’ll begin with individual understanding.

One might argue that for individual understanding, not too much would change if we are suddenly flooded with large numbers of big new results. There is already far more mathematics out there than I have any hope of understanding (for example, despite being fascinated when Fermat’s Last Theorem was proved, I have made no attempt to understand the proof), and even among the parts that I do understand, the parts that I understand because I myself discovered them form a very small fraction, though a fraction that I understand more deeply than anything else (at least temporarily — after a while I forget things and lose quite a lot of the understanding I built up). However, one change, which seems positive, from the perspective of the building up of individual understanding, would be that we would have a much bigger choice of results that we could choose to study. Also, if we found ourselves stuck on some point, AI would be able to help us. The main likely negative change is that we would probably cease to exercise that part of our brains that we use when spending months or years struggling with a difficult research problem, which can be hugely helpful in developing understanding.

I say “likely” because in principle there would be nothing to stop us thinking about very hard problems without consulting LLMs, but in practice it seems unlikely that people would put in the same level of effort that they do now. The situation might a bit like what happened with satnavs, where one could always decide not to use them, to keep the part of the brain active that can look at a map, learn a route, and follow it, but in practice most people succumb to the temptation to use a satnav. (In fact, I myself do try to keep that part of my brain active, and was rather proud of finding my way somewhere recently when I had briefly looked up the route on my phone but then forgotten to bring the phone with me when I actually went there.) But even if all we were doing was reading AI output, I think that the problem-solving muscles in the brain wouldn’t atrophy completely. When students are reading maths papers, I strongly advise them (and I think this is pretty standard advice) to read “actively” rather than “passively”, doing things like trying to prove the result for yourself, looking at the paper only when you feel stuck and need a hint, and even then just trying to get the hint and as little extra as possible. If one reads a paper that way, then one is constantly solving problems, some just exercises and some quite a bit harder. It seems likely that an LLM could get to know what our mathematical background is and feed us with just the right hints to allow us to work our way through a mathematics paper in this active way. Yes, we would lose the particularly deep level of understanding and ownership that comes with having solved a hard problem oneself, but it isn’t clear to me that progress in mathematics would suffer as a result. I would be very interested to hear counterarguments to precisely this point. That is, I would be interested to know what use that level of deep involvement with a proof might have in a world where AI is much better than we are at finding proofs.

How about collective understanding? Let me quote a bit more of the letter.

Indeed, the mass production at faster and faster pace of “true/false” statements could destroy fertile ground instead of breathing life into new ideas.

Often these solutions are announced in a rush, leaving no time for a proper writeup, the isolation of new methods and ideas, and citing relevant previous work of others. As in all creative professions, this raises severe attribution and plagiarism questions. Moreover, without the willing mathematicians who must take care of their development and integration into the mathematical canon, AI-conceived ideas would never become fully alive and the crucial human transmission chain between mathematicians would be lost.

I’ll come back to questions about proper citation and focus on what I take as the core worry here: that if results are proved too quickly, then the digestion process will become impossible. I am definitely worried that results will not be properly digested, but for different reasons.

A first remark is that what AI is producing is not just true/false statements: we now know not just that the Navier-Stokes equation with smooth forcing admits finite-time blow-up, but we have a proof of that, which builds on a great deal of wonderful work done by human mathematicians. Many people used to express the worry that AI would solve our favourite problems with utterly opaque proofs, but that has not turned out to be the case, even if their write-ups often leave plenty to be desired. (Incidentally, I see these inadequate write-ups as almost certainly a temporary annoyance and therefore not as a fundamental threat to mathematical practice or future mathematical understanding.)

Secondly, even if the volume of new results is large, mathematics is a highly specialized discipline, so mathematicians can work in parallel. If, for example, we had to digest 1000 important results in a year that were roughly uniformly distributed across mathematics, then most sub-communities of mathematicians would probably want to understand around 30 of them, and for each individual problem there might well be only a small handful of specialists who would be obvious people to take the lead in reaching this understanding, with that handful varying from problem to problem. So it would be a big task, but not necessarily an impossible one.

In this context, it is worth thinking about the huge volume of output of human mathematicians, which seems to have been increasing recently, even before AI. While I have sometimes heard complaints about this, I have certainly not heard suggestions that human mathematicians should slow down the rate at which they prove interesting theorems. That may be partly because the authors of those theorems take the trouble to write their papers well and give good talks. But what about the large quantity of papers, including important ones, that are not written well and whose authors give incomprehensible talks? That can be annoying, but it is a familiar annoyance and not one that we think of as a crisis.

A third point is that even if the volume of AI output is too big for us to be able to digest it properly, that is not necessarily a bad thing. To draw an imperfect analogy, there is now more content available on streaming services than anyone could possibly watch, with the result that there is almost certainly some very good content out there that is hardly watched at all. But that isn’t obviously a worse situation than if there were far less content and all of it received the attention it deserved. Returning to mathematics, if there were too much AI-generated content for us to be able to digest it, then we could choose which parts of it we wanted to digest.

For that we would need to have some idea what was there (a situation a little similar to how human mathematicians typically learn quite a lot about what results are known in their area even when they do not understand their proofs in any detail). One way one could try to achieve that would be to create a well-designed database, probably with AI help. But perhaps that would be unnecessary, and instead one could simply talk to an LLM and ask it to give a bird’s-eye view of whatever area of mathematics one wanted to understand in that knowing-what’s-there way.

The fear seems to be that some very interesting and important parts of mathematics will be discovered by AI and then overlooked, when had they been discovered by human mathematicians they would not have been overlooked. And that may even be the case, but what matters is whether the amount of interesting and important mathematics discovered by AI that is not overlooked will exceed the amount of interesting and important mathematics that would have been discovered and properly digested by humans with AI having played a more modest role.

In short, it seems to me that while a flood of “big” AI results would be likely to increase the amount of important mathematics that was not properly digested, it would also be likely to increase the amount that was properly digested, which seems like a pretty good bargain.

Let me quickly discuss the problem of AI not properly crediting human mathematicians. I agree that this is a serious problem right now, but it is another problem that I see as temporary. Very soon, the whole “credit system” will surely collapse, since finding an amazing proof will be no more of an intellectual achievement than when a citizen scientist spots through their telescope an object that turns out to be a new comet. Until that happens, it is important to give humans the credit they deserve, since careers can depend on it, but that will soon cease to be the case as well. I have to say that I’m puzzled that this problem exists, since I would have thought that if you asked an LLM to look at a proof and tell you which ideas in it are close to ideas that are in the literature already, it would be extremely good at that task. I hope the answer to this conundrum is not that people have been in such a hurry that they have simply not taken the trouble to do this, but I fear that it might be, at least in some cases. If so, then those who have been careless deserve to be criticized, but it is a minor matter compared with the survival of mathematics, especially if the lack of citations is swiftly put right.

Does all this mean that I am optimistic that mathematicians will end up digesting at least as much mathematics in a post-AI world as it would have if AI had not been able to prove major theorems? Not exactly. But my worry is not that we would be unable to do it, but rather that the social structures that currently support this digestion process will be destroyed and not adequately replaced.

One way that might happen is that AI disrupts society so much, or even kills vast numbers of us, that the preservation of something like the current mathematical tradition ceases to be of any concern: all that will matter is the survival of the human race. But that again is a topic for a different blog post (which in fact I am in the middle of writing).

Let’s assume instead that we get lucky and that AI remains more or less under control. My worry then is that we do not manage to transmit what we know to a new generation of mathematicians. Speaking for myself, my main motivation for becoming a mathematician was the dream that I would solve unsolved problems — the more famous the better. I have also always greatly preferred directly thinking about a problem to reading books and papers and generally learning the mathematics of other people. (I’m not saying that’s good, but just stating a fact about myself.) If the dream of solving a famous problem had not existed, I’m not sure whether I would have become a mathematician. I don’t completely rule it out: maybe what really motivated me was that I had an aptitude for the subject and that solving problems was a way of getting respect from a small group of peers. And maybe I could have tried to gain that respect in a different way, such as thinking very hard about an area of mathematics until I was able to demonstrate to others just how well I understood it. But I’m not sure how motivating that would have been for me. I very much hope that there is a pool of young people for whom it will be a powerful motivation, because I think the survival of a human mathematical tradition may well depend on it.

Thus, the primary risk, as I see it, is that a lot of people who would have done a PhD in mathematics and gone on to become custodians of the mathematical tradition will no longer wish to do so. Those of us who have PhD students, including me, need to try as hard as we can to come up with imaginative ways for them to use their time productively (in consultation with the students themselves, obviously). Whether or not we do a good job with that could make a huge difference to the future of mathematics. A related risk is that the perception among policy-makers will be that mathematicians are no longer needed and that funding will become much harder to come by: we urgently need to come up with good ways of explaining the value of having a large pool of human mathematical experts, even if it is no longer part of their role to find new proofs of theorems.

A final reason that I didn’t sign the letter is that I wasn’t really sure what it was demanding that isn’t happening already. It seems likely that in a matter of not very many months LLMs will be released that are able to solve major mathematical problems, and they will presumably have no trouble at all with more run-of-the-mill problems. However much we might regret that, there is no chance that the impact of such models on mathematics will persuade AI companies to stop their release, though perhaps concerns about safety will lead to some delay and give us a bit more time to work out how to adapt. Assuming that they are released, there will be a flood of new results, whether we like it or not, and it will no longer be the AI companies producing them, though perhaps the pattern will continue that the AI companies will have access to more powerful models and so will obtain more than their fair share of headline results. So I felt that there was nothing to be gained from criticizing AI companies for generating too many solutions too quickly. In fact, it may well be that all that does is bring forward by a couple of months what was going to happen anyway, and perhaps it will even allow the results to be released in a more controlled way than they would have been if they had been discovered by random people once the models were publicly available. Under the circumstances, I think the best we can do is recognise the changes that are coming and try to work out the least unsatisfactory way of dealing with them.

September 11, 2026

Andrew Jaffe — The Talk I Gave on September 12

More 25th anniversary thoughts and recollections.

I had moved to Oxford less than two weeks before, still settling into my new life in the UK, working at Imperial College in London. That day, I was heading off to Durham, in the north of England, to a conference called “A New Era in Cosmology” — my first big talk now that I had started my permanent academic job. I was going to be a bit late, only able to arrive toward the end of the first day of the conference: September 11, 2001.

My train left in the late morning. A few hours in, passengers were starting to talk about an attack on New York City. This was in the days before smartphones and constant communication — I didn’t even have a mobile phone. The discussions around me were getting more and more frantic, and I was doing my best to piece together the story.

I was born in New York City, and much of my family still lived in the area. My parents lived in the suburb of Fort Lee, New Jersey, right across the Hudson River from Manhattan; from the apartment where I grew up, we had a fantastic view from the 18th floor. My father worked in The City, commuting every morning by car from New Jersey to midtown Manhattan. He would have been at his office that day.

I considered getting off the train somewhere en route, perhaps Sheffield or York, to try to get some more information, but I just stayed on the train. I was able to get a taxi from the station in Durham to my hotel, listening to the news. I was able to call my partner, back in Oxford, who had, luckily considering the pressure on transatlantic calls, been able to get in touch with my family in New York and New Jersey. Everyone was, thankfully, alright, although at this point my father was still in Manhattan. He had noticed all the emergency vehicles speeding downtown, thinking that it was a motorcade for some foreign dignitary, but it was the first fleet of emergency responders heading towards the twin towers after the first collision. Eventually, he made it home, to my family’s apartment overlooking the Hudson. But it was so close to the George Washington Bridge, a piece of vital infrastructure thought to be in danger after the first attack, that he had to be let off a mile or so away and walk the rest.

As for me, I had to give the first talk on 12 September, about the “new era in cosmology” that coming CMB measurements would usher in. We started, understandably, with a few moments of silence, and I remember trying to come up with some appropriate words with which to start, something about needing to persevere even in the face of terrible events. I also recall that it was given on old-fashioned transparencies (I should try to dig it out of my files…) and that it was actually one of the better talks I had ever given, calmed, or at least slowed compared to my usual nervous agitation, by the events.

(My friend and colleague Peter Coles was also at the conference, offering his own reminiscences on his blog.)

As I mentioned in my last post, 9/11 feels like a milestone, and a millstone — the world hasn’t been the same since. And we still need to persevere in the face of terrible events.

Andrew Jaffe — The Talk I Gave on September 12

More 25th anniversary thoughts and recollections.

I had moved to Oxford less than two weeks before, still settling into my new life in the UK, working at Imperial College in London. That day, I was heading off to Durham, in the north of England, to a conference called “A New Era in Cosmology” — my first big talk now that I had started my permanent academic job. I was going to be a bit late, only able to arrive toward the end of the first day of the conference: September 11, 2001.

My train left in the late morning. A few hours in, passengers were starting to talk about an attack on New York City. This was in the days before smartphones and constant communication — I didn’t even have a mobile phone. The discussions around me were getting more and more frantic, and I was doing my best to piece together the story.

I was born in New York City, and much of my family still lived in the area. My parents lived in the suburb of Fort Lee, New Jersey, right across the Hudson River from Manhattan; from the apartment where I grew up, we had a fantastic view from the 18th floor. My father worked in The City, commuting every morning by car from New Jersey to midtown Manhattan. He would have been at his office that day.

I considered getting off the train somewhere en route, perhaps Sheffield or York, to try to get some more information, but I just stayed on the train. I was able to get a taxi from the station in Durham to my hotel, listening to the news. I was able to call my partner, back in Oxford, who had, luckily considering the pressure on transatlantic calls, been able to get in touch with my family in New York and New Jersey. Everyone was, thankfully, alright, although at this point my father was still in Manhattan. He had noticed all the emergency vehicles speeding downtown, thinking that it was a motorcade for some foreign dignitary, but it was the first fleet of emergency responders heading towards the twin towers after the first collision. Eventually, he made it home, to my family’s apartment overlooking the Hudson. But it was so close to the George Washington Bridge, a piece of vital infrastructure thought to be in danger after the first attack, that he had to be let off a mile or so away and walk the rest.

As for me, I had to give the first talk on 12 September, about the “new era in cosmology” that coming CMB measurements would usher in. We started, understandably, with a few moments of silence, and I remember trying to come up with some appropriate words with which to start, something about needing to persevere even in the face of terrible events. I also recall that it was given on old-fashioned transparencies (I should try to dig it out of my files…) and that it was actually one of the better talks I had ever given, calmed, or at least slowed compared to my usual nervous agitation, by the events.

(My friend and colleague Peter Coles was also at the conference, offering his own reminiscences on his blog.)

As I mentioned in my last post, 9/11 feels like a milestone, and a millstone — the world hasn’t been the same since. And we still need to persevere in the face of terrible events.

September 09, 2026

John Baez — The E6 Root Polytope

I’ve been thinking about the exceptional Lie algebra E6, as a spinoff of my project on E7, so I want to get a good mental picture of the E6 root polytope. This is 6-dimensional polytope with remarkable symmetry.

Let’s climb up to it, starting with some of its 4-dimensional faces, which are called 4-demicubes because you get them by taking a 4-dimensional cube, or tesseract, and removing every other corner. The 3-demicube is just a tetrahedron, since you can fit two tetrahedra in a 3-dimensional cube like this:

The 4-demicube builds on this fact in a surprising way.

I’m going to use the technology of Dynkin diagrams, or technically Coxeter diagrams: they’re closely related, and the difference is invisible here. I won’t explain them, just use them. I explained them here:

• Symmetry and the fourth dimension: part 3, part 4, part 5, part 6.

Let’s dive in!

The 4-demicube lives in 4 dimensions. It has 8 vertices.

You get it from a 4-dimensional cube, which has 24 = 16 vertices, by keeping every other vertex, throwing away half. That leaves 8.

What are its top-dimensional faces, aka ‘facets’? Surprise: there’s only one kind! All of them are regular tetrahedra.

In higher dimensions the demicube has two kinds of facet. You get a simplex-shaped facet from every other vertex, formed when you remove it. And you get a demicube-shaped facet from each of the cube’s facets. But in 4 dimensions the two kinds happen to be the same shape!

Eight of them are tetrahedra. These appear at the 8 corners you sliced off: one per removed corner.

Eight more come from the 8 faces of the 4-dimensional cube. These are 3-demicubes. But as we’ve seen, the 3-demicube is also a tetrahedron!

So the 4-demicube is especially symmetric: it has 16 tetrahedral facets. You can find coordinates where its vertices are

(±1, 0, 0, 0),   (0, ±1, 0, 0),   (0, 0, ±1, 0),   (0, 0, 0, ±1)

It’s actually one of the 4-dimensional regular polytopes, sometimes called the 4-orthoplex. It’s also called the 16-cell because it has 16 facets. It’s the 4-dimensional cousin of the octahedron, which has 8 triangular facets.

You can read some of these facts off the D4 Dynkin diagram, if you know what you’re doing. As you can see above, this diagram has a central node with three arms, each just 1 edge long: a perfectly symmetric three-pronged star. To get the 4-demicube, you ring the tip of any one arm.

To get the facets of the 4-demicube, delete an unringed node so the piece still holding the ring stays connected, and see what diagram survives. There are two choices: you can delete the tip of either other arm. But either way, what’s left is a straight chain of 3 nodes—the so-called A3 diagram—with a ring at one node at the end. This gives the tetrahedron.

Both choices give the same shape of facet, a tetrahedron, because all three arms of the D4 Dynkin diagram are interchangeable. That ceases to be true in higher dimensions!

 

Next, the 5-demicube. This lives in 5 dimensions and has 16 vertices.

You get it from a 5-dimensional cube—which has 25 = 32 vertices—by keeping every other vertex, throwing away half. That leaves 16.

What are its top-dimensional faces, or ‘facets’? There are two kinds!

Sixteen of them are 4-dimensional analogues of the regular tetrahedron, called 4-simplexes. These appear at the corners you sliced off: one per removed corner.

The other ten come from the ten faces of the 5-dimensional cube. After you take every other vertex, they become 4-demicubes. These are precisely the 4-demicubes we saw in the last section!

You can also read these two kinds of facets from the D5 Dynkin diagram. As you can see above, this diagram has three arms of lengths 2, 1, 1 (edges from the central branch node). To get the 5-demicube, you ring the tip of either length-1 arm. That ringed diagram encodes the whole polytope.

To get the facets, delete an unringed node so the piece still holding the ring stays connected, and see what diagram survives.

There are two choices.

If you delete the tip of the other length-1 arm, what’s left is a straight chain of 4 nodes—the diagram whose polytope is the 4-simplex. That gives the 4-simplex faces.

Or you can delete the tip of the length-2 arm. Then what’s left is a shorter branching diagram, the one I showed you in my last post! That gives the 4-demicube faces.

So the 5-demicube has both 4-simplex and 4-demicube faces.

Next let’s go up to the 6th dimension, which was my goal all along.

 

The E6 root polytope lives in 6 dimensions. It has 72 vertices.

What are its facets? You can read them straight off the E6 Dynkin diagram, using the same procedure we’ve been using so far.

As you can see, the E6 Dynkin diagram has three arms of lengths 2, 2, 1 (edges from the central branch node). To get the root polytope, you ring the node that’s the tip of a length-1 arm. That fact is not obvious, but let’s go ahead and do that.

Then, to get the facets, delete any unringed node such that the piece still holding the ring stays connected, and see what diagram survives.

There are two choices: the two other nodes at tips of the Dynkin diagram.

However, deleting either of these nodes leave a D5 diagram with a ring on one node, and this gives the 5-demicube we saw last time: a 5-cube with alternate vertices removed.

So the facets of the E6 root polytope are all the same shape: 5-demicubes!

With more work, we can count the facets of the polytopes we’ve been studying:

• The E6 root polytope has 54 facets, all 5-demicubes. They come in two kinds, because we had two choices of which node to delete, so there are really 27 ‘positive’ 5-demicube facets and 27 ‘negative’ 5-demicube facets.

• The 5-demicube has 16 4-simplex facets, one for each vertex that we removed from the 5-cube to create this demicube, and 10 4-demicube facets, one for each facet of that 5-cube.

• The 4-demicube has 8 3-simplex facets, one for each vertex that we removed from the 4-cube to create this demicube, and 8 3-demicube facets, one for each facet of that 4-cube. But both the 3-simplex and the 3-demicube are the familiar tetrahedron. So in fact the 4-demicube has 16 tetrahedral facets. Indeed, the 4-demicube is the 4-dimensional analogue of an octahedron: the so-called 4-orthoplex, or 16-cell.

Using some fancier math I explained here, we can count all the faces of the E6 root polytope. This polytope, is also called 122 due to the shape of its Dynkin diagram: the ring is on a branch of length 1, not counting the central node, while the other two branches have lengths 2. You can look up all this information on the Wikipedia page 122 polytope:

Faces of the E6 root polytope, or 122
dim faces count
5 5-demicubes 54 = 27 + 27
4 4-demicubes = 4-orthoplexes 270
4 4-simplexes 432 = 216 + 216
3 3-simplexes = 3-demicubes = tetrahedra 2160 = 1080 + 1080
2 2-simplexes = triangles 2160
1 1-simplexes = edges 720
0 0-simplexes = vertices 72

The 5-dimensional facets are all 5-demicubes, but as we’ve seen, they come in two kinds: that is, they lie in two orbits of the symmetry group. We can call 27 of them ‘positive’ 5-demicubes and 27 of them ‘negative’ demicubes. Of the 4-dimensional faces, 270 are 4-demicubes and 432 are 4-simplexes. Moreover the 4-simplexes come in two kinds: 216 are faces of positive 5-demicubes while 216 are faces of negative 5-demicubes. Let’s call the first kind of 4-simplex ‘positive’ and the second kind ‘negative’. The 3-dimensional faces are all tetrahedra, but they come in two ‘kinds’: 1080 of them are faces of positive 4-simplexes, and 1080 are faces of negative 4-simplexes. None is the face of both a positive and negative 4-simplex.

If you’re curious about how to count these things, see how some of us counted all the faces of the E8 root polytope here:

• John Baez, Integral octonions (part 5), The n-Category Café, September 3, 2013.

Here is a table of faces for the E7 root polytope, which is also called 231:

Faces of the E7 root polytope, or 231
dim faces count
6 221 polytopes 56
6 6-simplexes 576
5 5-orthoplexes 756
5 5-simplexes 4032
4 4-simplexes 16128 = 4032 + 12096
3 3-simplexes = tetrahedra 20160
2 2-simplexes = triangles 10080
1 1-simplexes = edges 2016
0 0-simplexes = vertices 126

Its 4-dimensional faces are all 4-simplexes, but they come in two ‘kinds’: that is, they lie in two orbits of the symmetry group of this polytope. Of the 4-simplexes, 4032 are the face of three 5-orthoplexes, while 12096 are the face of one 5-orthoplex and two 5-simplexes.

Here’s the E8 root polytope, also called 421:

Faces of the E8 root polytope, or 421
dim faces count
7 7-orthoplexes 2160
7 7-simplexes 17280
6 6-simplexes 207360 = 138240 + 69120
5 5-simplexes 483840
4 4-simplexes 483840
3 3-simplexes = tetrahedra 241920
2 2-simplexes = triangles 60480
1 1-simplexes = edges 6720
0 0-simplexes = vertices 240

There are two kinds of 6-simplex faces: 138240 of them each lie in one 7-simplex and one 7-orthoplex, while 69120 of them each lie in two 7-orthoplexes (and no 7-simplex).

Andrew Jaffe — Second test post

Andrew Jaffe — Test post

Checking some infrastructure…

September 08, 2026

n-Category Café The E6 Root Polytope

I’ve been thinking about the exceptional Lie algebra E6, as a spinoff of my project on E7, so I want to get a good mental picture of the E6 root polytope. This is 6-dimensional polytope with remarkable symmetry.

Let’s climb up to the E6 root polytope starting with some of its 4-dimensional faces, which are called 4-demicubes because you get them by taking a 4-dimensional cube, or tesseract, and removing every other corner. The 3-demicube is just a tetrahedron, since you can fit two tetrahedra in a 3-dimensional cube like this:

The 4-demicube builds on this fact in a surprising way.

I’m going to use the technology of Dynkin diagrams, or technically Coxeter diagrams: they’re closely related, and the difference is invisible here. I won’t explain them, just use them. I explained them here:

• Symmetry and the fourth dimension: part 3, part 4, part 5, part 6.

Let’s dive in!

The 4-demicube lives in 4 dimensions. It has 8 vertices.

You get it from a 4-dimensional cube, which has 24 = 16 vertices, by keeping every other vertex, throwing away half. That leaves 8.

What are its top-dimensional faces, aka ‘facets’? Surprise: there’s only one kind! All of them are regular tetrahedra.

In higher dimensions the demicube has two kinds of facet. You get a simplex-shaped facet from every other vertex, formed when you remove it. And you get a demicube-shaped facet from each of the cube’s facets. But in 4 dimensions the two kinds happen to be the same shape!

Eight of them are tetrahedra. These appear at the 8 corners you sliced off: one per removed corner.

Eight more come from the 8 faces of the 4-dimensional cube. These are 3-demicubes. But as we’ve seen, the 3-demicube is also a tetrahedron!

So the 4-demicube is especially symmetric: it has 16 tetrahedral facets. You can find coordinates where its vertices are

(±1,0,0,0),(0,±1,0,0),(0,0,±1,0),(0,0,0,±1)(\pm 1, 0, 0, 0), \quad (0, \pm 1, 0, 0), \quad (0, 0, \pm 1, 0), \quad (0, 0, 0, \pm 1)

It’s actually one of the 4-dimensional regular polytopes, sometimes called the 4-orthoplex. It’s also called the 16-cell because it has 16 facets. It’s the 4-dimensional cousin of the octahedron, which has 8 triangular facets.

You can read some of these facts off the D4 Dynkin diagram, if you know what you’re doing. As you can see above, this diagram has a central node with three arms, each just 1 edge long: a perfectly symmetric three-pronged star. To get the 4-demicube, you ring the tip of any one arm.

To get the facets of the 4-demicube, delete an unringed node so the piece still holding the ring stays connected, and see what diagram survives. There are two choices: you can delete the tip of either other arm. But either way, what’s left is a straight chain of 3 nodes—the so-called A3 diagram—with a ring at one node at the end. This gives the tetrahedron.

Both choices give the same shape of facet, a tetrahedron, because all three arms of the D4 Dynkin diagram are interchangeable. That ceases to be true in higher dimensions!

 

Next, the 5-demicube. This lives in 5 dimensions and has 16 vertices.

You get it from a 5-dimensional cube—which has 25 = 32 vertices—by keeping every other vertex, throwing away half. That leaves 16.

What are its top-dimensional faces, or ‘facets’? There are two kinds!

Sixteen of them are 4-dimensional analogues of the regular tetrahedron, called 4-simplexes. These appear at the corners you sliced off: one per removed corner.

The other ten come from the ten faces of the 5-dimensional cube. After you take every other vertex, they become 4-demicubes. These are precisely the 4-demicubes we saw in the last section!

You can also read these two kinds of facets from the D5 Dynkin diagram. As you can see above, this diagram has three arms of lengths 2, 1, 1 (edges from the central branch node). To get the 5-demicube, you ring the tip of either length-1 arm. That ringed diagram encodes the whole polytope.

To get the facets, delete an unringed node so the piece still holding the ring stays connected, and see what diagram survives.

There are two choices.

If you delete the tip of the other length-1 arm, what’s left is a straight chain of 4 nodes—the diagram whose polytope is the 4-simplex. That gives the 4-simplex faces.

Or you can delete the tip of the length-2 arm. Then what’s left is a shorter branching diagram, the one I showed you in my last post! That gives the 4-demicube faces.

So the 5-demicube has both 4-simplex and 4-demicube faces.

Next let’s go up to the 6th dimension, which was my goal all along.

 

The E6 root polytope lives in 6 dimensions. It has 72 vertices.

What are its facets? You can read them straight off the E6 Dynkin diagram, using the same procedure we’ve been using so far.

As you can see, the E6 Dynkin diagram has three arms of lengths 2, 2, 1 (edges from the central branch node). To get the root polytope, you ring the node that’s the tip of a length-1 arm. That fact is not obvious, but let’s go ahead and do that.

Then, to get the facets, delete any unringed node such that the piece still holding the ring stays connected, and see what diagram survives.

There are two choices: the two other nodes at tips of the Dynkin diagram.

However, deleting either of these nodes leave a D5 diagram with a ring on one node, and this gives the 5-demicube we saw last time: a 5-cube with alternate vertices removed.

So the facets of the E6 root polytope are all the same shape: 5-demicubes!

With more work, we can count the facets of the polytopes we’ve been studying:

• The E6 root polytope has 54 facets, all 5-demicubes. They come in two kinds, because we had two choices of which node to delete, so there are really 27 ‘positive’ 5-demicube facets and 27 ‘negative’ 5-demicube facets.

• The 5-demicube has 16 4-simplex facets, one for each vertex that we removed from the 5-cube to create this demicube, and 10 4-demicube facets, one for each facet of that 5-cube.

• The 4-demicube has 8 3-simplex facets, one for each vertex that we removed from the 4-cube to create this demicube, and 8 3-demicube facets, one for each facet of that 4-cube. But both the 3-simplex and the 3-demicube are the familiar tetrahedron. So in fact the 4-demicube has 16 tetrahedral facets. Indeed, the 4-demicube is the 4-dimensional analogue of an octahedron: the so-called 4-orthoplex, or 16-cell.

Using some fancier math I explained here, we can count all the faces of the E6 root polytope:

dim faces count
5 5-demicubes 54 = 27 + 27
4 4-demicubes = 4-orthoplexes 270
4 4-simplexes 432
3 3-demicubes = 3-simplexes = tetrahedra 2160 = 1080 + 1080
2 2-simplexes = triangles 2160
1 1-simplexes = edges 720
0 0-simplexes = vertices 72

If you’re curious about how to count these things, see how some of us counted all the faces of the E8 root polytope here:

Andrew Jaffe — 25 & 60

Twenty-five years ago, I moved from San Francisco to the UK, from a fellowship at Berkeley to a permanent job at Imperial College, London. A lot has changed since then. I was 35; now I am 60. It was two weeks before 9/11; the world hasn’t seemed as open and free since.

I arrived from the Bay Area just after the first dot-com bubble burst. London, adjusting to New Labour after almost two decades of Thatcher and Thatcherism, felt exciting and vibrant. But just weeks after I arrived came the horror of 9/11, and its years-long aftermath, especially the Iraq war which eventually doomed Blair’s premiership and probably led the way to the 2010 election, the disaster of “austerity” as a wrong-headed attempt to deal with the 2008 recession, and eventually to the more-disastrous Brexit on this side of the Atlantic. Similar politics, though with very different timing, led back in the USA to Obama, one of the few rays of political hope over the last quarter-century, but then, of course, to Trump. And everywhere since 2001 the rise of nativist populism making me feel at home, well, pretty much nowhere — a rootless cosmopolitan. Higher education, scientific funding, and curiosity-driven research are in a parlous state in both the US and the UK.

But: despite a few difficult years in the mid-2000s, I have prospered. Our analysis of data from the Planck satellite has solidified our standard cosmological model — but also given us new problems and puzzles to think and worry about. I have written a book, The Random Universe, trying to explain how we know what we know as scientists and as human beings. And my family, my wife and two daughters, are a source of joy and excitement that inspire me every day.

So now I am 60. I was honoured and humbled a couple of months to ago to be joined by many of my colleagues and scientific friends at a conference here in London. That, and getting a Transport For London 60+ Travel Card, makes it hard to avoid feeling old. But those colleagues and friends (many of whom are older than me) reassured me that it’s only the beginning of a new chapter.

September 06, 2026

John Baez — The Mantle

As we descend from the base of Earth’s crust through the mantle, the rock does not remain unchanged. Pressure and temperature rise inexorably, and the minerals that thrive at the surface are forced, step by step, into new and denser crystallographic arrangements. This is the story of those transformations.

In this tale, I’ll act like I know a bit about minerals. I actually don’t: there are a bewildering variety, and I can never remember them. So don’t worry: when you come across a jargon-filled patch of prose, just power through it. You might learn a little… or you can just ignore it. The overall point here is that the Earth is made of beautiful crystalline structures that change character in complex ways as we descend.

The Mohorovičić discontinuity

Our story begins at the boundary where Earth’s crust, rich in feldspar and quartz, gives way to the denser mantle beneath. We see this boundary through its effect on seismic waves, and it’s called the Mohorovičić discontinuity or “Moho”. The Moho does not lie at one fixed depth: it’s 5–10 kilometers below the seafloor, but 30–50 kilometers below most continents, and as much as 70–80 below young mountain belts like the Himalayas.

The mantle just below the Moho mainly consists of a rock called peridotite, which is made mostly of olivine and pyroxene, with smaller amounts of garnet (or, at shallower depths, spinel). Peridotite has a delicious coarse green appearance:



More precisely, this is what peridotite looks like up here. But when geochemists talk about the bulk composition of the upper mantle, they often use an idealized model called pyrolite—not a rock you can pick up, but a hypothetical recipe Ted Ringwood proposed in the 1960s for the primitive upper mantle.

Why? Since the Earth has had a convecting mantle, solid mantle rock wells up in places. As it does, the pressure drops, and a bit of it melts: the minerals with lower melting points. This melt flows upward. It’s called basalt. It builds the Earth’s crust. But it leaves a residue behind, made of minerals with higher melting points.

In Ringwood’s theory, which for expository purposes I’ll assume is true, pyrolite is what mantle rock is like before any partial melting depletes it of basaltic ingredients. The name is a portmanteau of pyroxene and olivine, the two dominant minerals. Pyrolite is about 60% olivine; the remaining 40% is mostly pyroxenes plus garnet.

• A pyroxene is a mineral built from single, unbranched chains of corner-sharing SiO₄ tetrahedra, with metal cations—chiefly Mg, Fe, and Ca—linking the chains together. The general formula is XY(Si,Al)₂O₆, where X and Y are those cations.


• Olivine is a green silicate, (Mg,Fe)₂SiO₄:


Its crystal structure in the upper mantle is an orthorhombic arrangement of isolated SiO₄ tetrahedra knit together by magnesium and iron in octahedral sites. It’s called the α-phase because we’ll see some more compressed phases as we descend.

• A garnet is built from separate SiO₄ tetrahedra held together by cations, but assembled into a dense, hard, characteristically cubic-symmetry crystal. There are different kinds of garnet, but the general formula is X₃Y₂(SiO₄)₃: three divalent X cations, two trivalent Y cations, and three isolated silica tetrahedra. The mantle’s garnet is largely pyrope, Mg₃Al₂(SiO₄)₃.


As we descend, the pyroxenes and garnet gradually dissolve into each other, producing a new high-pressure mineral called majorite. Here’s a rare sample from a meteorite fall in Canada:


So even before the dramatic change 410 kilometers down, the rock is no longer the simple olivine-pyroxene-garnet assemblage we had further up.

The 410-kilometer discontinuity

Roughly 410 kilometers down, the pressure reaches about 13,000 atmospheres and the temperature hovers around 1,400°C. Olivine can no longer hold its familiar shape. It transforms to its β form: wadsleyite, a mineral with the same chemical formula but a fundamentally different atomic arrangement. Instead of isolated SiO₄ tetrahedra, wadsleyite contains paired Si₂O₇ groups, and the oxygens pack more densely. The density jump is sharp enough to be detected globally by seismologists as a reflector of earthquake waves.

Wadsleyite has a remarkable property: it can hold several weight percent of water locked within its crystal structure. The transition zone may thus contain more water than all the oceans combined! However, very little wadsleyite has been seen on the Earth’s surface. Here’s a bit from that same meteor fall in Canada:


The 520-kilometer discontinuity

Descend further, to around 520 kilometers, and the temperature goes up only a little, to roughly 1500–1600°C, since convection here is strong. The pressure goes up to about 175,000 atmospheres. At this point wadsleyite transforms into the γ form of olivine: ringwoodite. This is denser, still chemically Mg₂SiO₄, but now with cations packed into tetrahedral and octahedral holes in a close-packed oxygen framework—the most efficient packing geometry that nature offers for this composition:


Ringwoodite is named for the great Australian geochemist Ted Ringwood, who studied these transitions. Here’s an artificially manufactured sample:


For a long time the mineral’s existence in the mantle was purely hypothetical. But in 2014, a tiny grain was discovered as an inclusion inside a diamond brought up from the deep mantle by an eruption, providing the first direct proof of its existence in Earth’s interior.

The 660-kilometer discontinuity

At a depth of 660 kilometers and a pressure of roughly 230,000 atmospheres, the most dramatic phase transition of all occurs. Ringwoodite does not merely rearrange into a still more dense form! Instead, it decomposes into two entirely new minerals: bridgmanite (MgSiO₃) and ferropericlase (MgO). The majorite garnet also decomposes, yielding davemaoite (CaSiO₃), which is stable through the rest of the lower mantle:



The 660-kilometer discontinuity is sharp, globally consistent, and marks the conventional boundary between the upper and lower mantle. One reason it’s important is that enormous slabs of colder, denser rock sink through the upper mantle until they hit this discontinuity, where the phase change between ringwoodite and bridgmanite creates a kind of barrier.

These slabs are 30–100 kilometers thick and hundreds to a thousand kilometers across! Some punch straight through into the lower mantle and keep sinking. But many flatten out when they hit the barrier, sometimes lying there and piling up for tens of millions of years. You can see this in seismic images beneath Japan and the Marianas. Numerical models suggest that they pile up until they overwhelm the barrier and flush down in a comparatively sudden avalanche—lasting mere millions of years.

The lower mantle

This is the realm of bridgmanite, probably the most abundant mineral in the Earth. Bridgmanite is a beautifully symmetric cage of corner-sharing SiO₆ octahedra, with Mg tucked into the large cavities between them. It accommodates enormous pressure because there is very little void space left to compress.



It is a striking fact that while bridgmanite is the most abundant mineral on the planet, it went unnamed until 2014, simply because no natural hand-sized specimen had ever been recovered. Everything we know about it comes either from high-pressure laboratory synthesis, from microscopic grains in shocked meteorites, or from the indirect testimony of earthquake waves that have traveled through 2,000 kilometers of it.

For over 2,000 kilometers of descent, from 660 to roughly 2,700 kilometers down, bridgmanite and its companion ferropericlase reign without significant further phase change. Seismic velocities increase steadily, but there are no dramatic discontinuities.

The D″ discontinuity

As we approach the core-mantle boundary—at depths around 2,700 kilometers, pressures of approximately 120,000–125,000 atmospheres, and temperatures of 2,200–3,7000°C—even bridgmanite yields. It transforms into the post-perovskite phase. Post-perovskite is a layered, sheet-like structure of SiO₆ octahedra, quite different from bridgmanite’s three-dimensional cage, making it potentially much weaker and more prone to flow.

This transition is believed to be responsible for the seismic D″ discontinuity observed at 2,900 kilometers depth. The D″ layer is a highly dynamic region, likely the site of storage of subducted materials and the source of deep mantle plumes.

A summary of the descent

The table below summarizes the major transitions:

Depth (km)        Minerals
0–410 olivine (α) + pyroxenes + garnet
410 → wadsleyite (β)
520 → ringwoodite (γ)
660 → bridgmanite + ferropericlase + davemaoite
660–2700 bridgmanite dominates
~2700 → post-perovskite
2900 → liquid iron core

The interesting thing about this story is that it was told first by seismology—the sharp jumps in wave speeds at 410 and 660 kilometers were detected long before geologists could reproduce those pressures in the lab—and only later checked by diamond-anvil cell experiments squeezing tiny mineral samples to millions of atmospheres. The rocks never rise to the surface to tell their story directly, so much of the tale above is just theory.

Which minerals are there the most of?

We can estimate how much of the Earth is made of wadsleyite, ringwoodite, and bridgmanite using known shell volumes, estimated densities, and mineral proportions from the pyrolite model.

Step 1: Earth’s mass budget by layer

The Earth’s total mass is M⊕ ≈ 5.972 × 1024 kg. The mass budget by layer is approximately:

•    Crust: ~0.4% of Earth’s mass
•    Upper mantle + transition zone (35–660 km): ~18% of Earth’s mass
•    Lower mantle (660–2,891 km): ~49% of Earth’s mass
•    Core (outer + inner): ~32.5% of Earth’s mass

Step 2: The transition zone (410–660 km)

Using PREM densities averaging ~3,760 kg/m3 across the transition zone, and the volume of each spherical shell:

Wadsleyite zone (410–520 km):
Shell volume ≈ 4.8 × 1019 m3
Shell mass ≈ 1.76 × 1023 kg
Fraction of Earth’s mass ≈ 2.9%

Ringwoodite zone (520–660 km):
Shell volume ≈ 5.9 × 1019 m3
Shell mass ≈ 2.24 × 1023 kg
Fraction of Earth’s mass ≈ 3.8%

In the pyrolite model of mantle composition, forms of olivine (wadsleyite and ringwoodite) make up roughly 60% of the transition zone by mass, with the remaining ~40% being majoritic garnet. Applying this correction:

Wadsleyite: 0.60 × 2.9% ≈ 1.8% of Earth’s mass
Ringwoodite: 0.60 × 3.8% ≈ 2.3% of Earth’s mass

These estimates carry roughly 20–30% uncertainty, mainly from the assumed 60% olivine proportion in the transition zone, which varies with local temperature and bulk composition.

Step 3: Bridgmanite (660–2,700 km)

The lower mantle holds about 49% of Earth’s mass—it is an enormous shell! Bridgmanite constitutes approximately 80% of the lower mantle mineral assemblage (by mass) in the pyrolite model:

0.80 × 49% ≈ 39% of Earth’s mass

This is consistent with the well-cited literature figure that bridgmanite comprises approximately 38% of the planet’s mass—making it the single most abundant mineral in the Earth by a vast margin.

Mineral Depth (km) Fraction of Earth’s Mass
Wadsleyite 410–520 ~1.8%
Ringwoodite 520–660 ~2.3%
Bridgmanite 660–2,700 ~38–39%
All three combined 410–2,700 ~42%

Thus, these three minerals—all members of the same Mg₂SiO₄/MgSiO₃ chemical lineage—together constitute roughly 42% of Earth’s entire mass. All other named minerals on Earth, including quartz, feldspar, calcite, diamond, and the roughly 3,800 others known to mineralogists, divide up the remaining scraps.

September 01, 2026

n-Category Café Three Generations in E7

It’s long been a mystery why there are 3 generations of quarks and leptons: three sets of particles, apparently identical except for how they interact with the Higgs boson. It would be nice if there were some good physical explanation. Nobody knows one. Barring that, it would be nice if some beautiful mathematical structure made this pattern seem natural. That’s what my new paper is about.

I’ll keep this nontechnical. I’ll say a bit about what the paper does, what it does not do, what led up to it, and how I wrote it.

This is my third paper about exceptional algebraic structures and the Standard Model. When you classify famous gadgets in algebra, beautiful gadgets with fancy names like ‘simple Lie algebras’ and ‘Euclidean Jordan algebras’ and ‘positive hermitian Jordan pairs’, you tend to get infinite series of them — together with a few exceptions that can be built using the octonions. This is a bit spooky, so I’ve been interested in this for a long time.

A few physicists have hoped that these exceptions are good for something. For example, maybe the quirky features of our best theory of particle physics, the Standard Model, aren’t accidental. Perhaps they fall out naturally from some exceptional algebraic structure.

It’s a long shot, but we’ve been stuck on figuring out new fundamental laws of particle physics for so long — roughly since the early 1980s — that it’s worth a try.

In 2018, Michel Dubois-Violette and Ivan Todorov noticed that the gauge group of the Standard Model falls out as symmetries of the so-called ‘exceptional Jordan algebra’ together with some ordinary Jordan algebras sitting inside it. I tried to clarify that here, with a huge amount of help from an excellent young mathematician:

It’s very nice, because the Jordan algebras in question arise naturally when you try to axiomatize the foundations of quantum physics. It would be so cool if something about quantum physics made the Standard Model seem mathematically natural!

But really this result only concerns the gauge bosons in the Standard Model: the photon, gluons, and the W and Z bosons. It says nothing about the fermions — that is, the quarks and leptons. And it seems quite hard to get those into the picture.

In 2020, Latham Boyle tried to solve this problem by tensoring the exceptional Jordan algebra with the complex numbers. This made one generation of fermions appear quite naturally! But the connection to the foundations of quantum physics seemed lost: tensoring the exceptional Jordan algebra with the complex numbers seems at first like it might be just a formal trick.

This spring, Latham and his student Endre Bokor and I showed the connection to quantum physics is not lost:

The idea is to work, not with Jordan algebras, but with more general things called Jordan pairs, which have been studied by mathematicians since at least 1975. We showed that you can still do quantum physics with Jordan pairs. And we showed that there’s an ‘exceptional’ Jordan pair that naturally contains the Standard Model gauge group and one generation of fermions!

This Jordan pair is built from the bioctonions: the octonions tensored with the complex numbers. And it’s closely related to an exceptional Lie algebra called 𝔢 6\mathfrak{e}_6.

This is nice because the work of Dubois-Violette and Todorov used a smaller exceptional Lie algebra called 𝔣 4\mathfrak{f}_4. Going up to 𝔢 6\mathfrak{e}_6 gives the room to include one generation of fermions.

There’s an even larger exceptional Lie algebra you can use to build a Jordan pair: it’s called 𝔢 7\mathfrak{e}_7. Bokor, Boyle and I tried using this to get three generations of fermions. There are things that make this tempting: not just the fact that 𝔢 7\mathfrak{e}_7 is bigger, but the fact that the Jordan pair you get from it has a kind of three-fold symmetry. But we couldn’t get it to work.

Around this time I got very interested in some work that someone had sent me in October 2025. My inbox is packed with new theories of physics. Since the rise of large language models the inflow has increased: I get about two emails a day from someone telling me they’ve made a revolutionary discovery in physics. Practically none of these theories appeal to me. But this paper, and this thesis, were different:

He claimed to fit three generations of fermions into the exceptional Lie algebra 𝔢 7\mathfrak{e}_7.

When I started seriously trying to understand this paper, I wound up translating it into a language I’m more comfortable with, and expanding on the ideas a bit. So I wrote this:

Here’s the basic idea.

The idea

There is a standard way to fit the Lie algebra of the Standard Model gauge group, which I call 𝔤 SM\mathfrak{g}_{\text{SM}}, into the Lie algebra 𝔢 7\mathfrak{e}_7. You can construct a Lie algebra LL that fits between them:

𝔤 SM⊂L⊂𝔢 7 \mathfrak{g}_{\text{SM}} \subset L \subset \mathfrak{e}_7

As a vector space we have

𝔢 7≅L⊕V \mathfrak{e}_7 \; \cong \; L \oplus V

for some vector space VV of dimension 3×323 \times 32.

Moreover, the Lie algebra 𝔤 SM\mathfrak{g}_{\text{SM}} acts on VV, via the 𝔢 7\mathfrak{e}_7 Lie bracket, precisely as it does on three generations of Standard Model fermions and their antiparticles, including right-handed neutrino and its antiparticle — but ignoring spin!

There is, in fact, a very interesting three-fold symmetry built into 𝔢 7\mathfrak{e}_7, which is revealed when we put the Standard Model Lie algebra 𝔤 SM\mathfrak{g}_{\text{SM}} into it. It permutes the three generations.

Like Nasmith, I am not proposing a theory of physics. I’m only observing a fascinating mathematical pattern that might (or might not) be of some use in physics.

There are lots of things this pattern does not include: basically, everything I didn’t already mention. It does not include the spin of the fermions and gauge bosons. It does not include the Higgs boson, though in some sense it comes close (see the paper). It does not include a Lagrangian, so it doesn’t say anything at all about particle masses or interactions.

I could say a lot more about what my paper does do… most importantly, where this Lie algebra LL comes from! The details are very interesting. There’s also the curious role of the right-handed neutrinos. But I’ve already spent weeks explaining all these things in my paper, so I won’t do it here. Instead let me say a bit about how I wrote the paper.

Writing the paper

I’ve been wanting to keep up with how AI is transforming math. About a year ago a friend gave me a subscription to Claude Pro. I wanted to test it out, despite my many misgivings, including how large language models are contributing to global warming and income inequality. Given the amazing things that people have recently done in math using large language models, I didn’t think that never trying them out would put me in the best position to make good decisions about the future.

So, I wrote this paper with help from Claude Opus 4.8.

I started by giving it Nasmith’s paper and asking a long series of questions about that paper over several days. The results were very interesting and helpful. Eventually I asked it to summarize and expand on our conversation. It quickly spat out a 10-page paper.

This paper was written in a breezy, pleasant style — but also quite hard to understand in detail, since it mixed Nasmith’s terminology with the Lie algebra terminology I prefer, and the proofs skipped over some steps.

It took me about three weeks of hard work to fully understand and re-express all the ideas a way that I like. For a while I felt dumb and frustrated, because when I asked Claude to fill in the gaps in proofs, it used math I was not very competent in, like the theory of regular subalgebras, and the theory of minuscule representations. But I learned this math, and everything turned out to be basically correct — in part, I’m sure, because Nasmith’s original work was correct.

For several weeks I checked, reorganized, expanded and completely rewrote this material. By the end everything was written in a style I like, emphasizing the ideas I consider important, proving things fairly carefully, and adding a lot of expository material — for example, explaining the theory of regular subalgebras.

Almost no traces of Claude’s original writeup remain, even though I was deeply influenced by them. My proofs make few references to deep theorems, though they assume solid familiarity with simple Lie algebras and their root systems. The proofs also require no brutally hard computations — though Claude was eager to do such computations to check things.

Any mistakes in this paper are my own.

I’m not sure what conclusions I draw from writing this paper. I’m writing another math paper now, with a human coauthor, and I have no desire to get help from a large language model. For work on my own it could be very helpful. Fields medalist Jacob Tsimerman says it roughly doubles his productivity. Would using it be so bad for the environment, or so bad for society, that I should avoid it? Maybe. I deliberately stuck with Claude Opus 4.8 instead of something more powerful, to see what I could do with what you get from a $20/month subscription. But maybe that’s still bad.

I avoid flying to conferences, which in some ways cripples my ability to keep up with new trends and influence people — but I don’t mind that. It gives me more time to think.

I will think carefully about my next move.

August 13, 2026

Tim Gowers — What sort of maths are LLMs good at?

For the sake of anyone who might read this blog post in the distant future (a month from now, say), let me mention that I am writing it a few days after OpenAI announced that it had solved ten major problems in mathematics and theoretical computer science, including the first construction of a non-sofic group, and a proof that the multicolour Ramsey number R(3,3,...,3) (where there are k 3’s) grows superexponentially in k. The first was, to judge from various talks I have been to, one of the most important unsolved problems in group theory, and the second was a major open problem in Ramsey theory that I didn’t necessarily expect to see solved in my lifetime, though of course such expectations now have to be revised. The reason I want to be clear about the timing is that I shall be discussing the current capabilities of LLMs in the full expectation that those will continue to change rapidly. So it is likely that in not too long from now, if there is anything interesting in what I write, it will be interesting mainly as a record of what the situation looked like in early August 2026.

These results, and the other eight on the list, are extraordinarily impressive, but it still doesn’t seem to be the case that LLMs are better than all humans at all aspects of mathematics. If they were, then their big speed advantage over us would mean that there would be much more of a flood of results. So it is natural to wonder about what kinds of problems LLMs are good at, and about where there is still room for improvement. I don’t pretend to have a good answer to this question, where a good answer would be a crisp classification that would fit the current examples well, but it is an interesting exercise to try to rule out some bad answers, and to try to identify potential answers that aren’t obviously contradicted by the evidence.

Are LLMs particularly good at finding counterexamples?

A first remark here is that LLMs are not just good at finding counterexamples: they can find proofs of difficult statements as well. However, it is notable that the most famous problems they have solved have almost all been with counterexamples rather than proofs. That is true of the two problems mentioned above, and also of the Jacobian conjecture and the unit distance conjecture.

If one wants to theorize that LLMs are particularly good at finding counterexamples, then there are two things it would be good to do to make the theory more convincing. The first may sound unproblematic: it is to decide when solving a problem counts as finding a counterexample. Once that is sorted out, the second is to come up with a potential explanation of why LLMs would be particularly well suited to solving problems of that particular kind.

What does it mean to find a counterexample?

Why am I suggesting that it is not completely obvious what it means to find a counterexample? Surely, one might suggest, all it means is that you have a statement of the form “Every object of such and such a type has such and such a property,” and you exhibit an object of the given type that does not have the given property.

However, this doesn’t always work. Consider a famous result of Vinogradov, which states that every sufficiently large positive integer is a sum of three primes. The negation of this statement is (or is equivalent to) the statement that for every positive integer N there exists an integer n\geq N such that n is not a sum of three primes. In other words, it states that every positive integer N has a certain property. Seen in this light, Vinogradov found an example of a positive integer N that does not have the given property. Do we want to say that Vinogradov found a counterexample? Clearly not — the result should obviously be classified as a theorem and not a counterexample.

Thus, we cannot just naively say that LLMs are particularly good at negating universally quantified statements: there has to be something about the nature of the universal quantification. With the three-primes example, it is clear that Vinogradov did not think, “How am I going to find N with this property?” Rather, what he thought would have been more like, “I’ve got an integer n that is very large. How am I going to show that it is a sum of three primes?” In other words, all his focus would have been on the universally quantified n, with the existentially quantified N being a sort of afterthought once the details of the proof have been worked out.

In general, many interesting results, when they are stated formally, begin with an alternation of two or three (or more) quantifiers. The question then becomes to determine which is the first “interesting” quantified variable in some sense. Here’s another example to illustrate the point, from the theory of finite-dimensional normed spaces. I’ll give a few mathematical details for those curious, but if you don’t care about those, then you can skip the next three paragraphs and should get the gist of what I am saying about this example.

Let X and Y be two n-dimensional normed spaces and let T be a linear map from X to Y. We say that T is a C–isomorphism if there exists \lambda>0 such that \lambda\|x\|\leq\|Tx\|\leq C\lambda\|x\| for every x\in X. By rescaling we can always take \lambda to be 1, in which case we have that \|x\|\leq\|Tx\|\leq C\|x\| for every x\in X. If C=1, then this tells us that T is an isometry. In general, the Banach-Mazur distance d(X,Y) between X and Y is defined to be the smallest C such that there exists a C-isomorphism from X to Y. It is easy to see that the logarithm of the Banach-Mazur distance is a metric on the set of isometry classes of n-dimensional normed spaces. A less easy fact, but still not too hard, is that the resulting metric space is compact: in fact, it is known as the Banach-Mazur compactum.

It is natural to wonder what the diameter of the Banach-Mazur compactum is, and here things get interesting. A result of Fritz John states that every n-dimensional space X has distance at most \sqrt n from \ell_2^n. (The idea of the proof is as follows: pick inside the unit ball of X an n-dimensional ellipsoid of maximal volume; that is the unit ball of a normed space Y that is isometric to \ell_2^n; it can be shown that the identity map is a \sqrt n-isomorphism between X and Y.) From Fritz John’s theorem and the (multiplicative) triangle inequality, it follows that d(X,Y)\leq n for any two n-dimensional normed spaces. That is, the diameter of the Banach-Mazur compactum is at most n. But might it be substantially less than that?

An indication that the answer is not obvious comes from looking at the spaces \ell_1^n and \ell_\infty^n. The identity map between these two spaces is an n-isomorphism, but one can do much better by mapping the standard basis vectors not to themselves but to vertices of the unit cube, with the vertices chosen to be as orthogonal as possible. In particular, if there exists an n\times n Hadamard matrix, then the corresponding linear map is a \sqrt n-isomorphism. One can push this observation and deduce that for any p,q\in[1,\infty] the Banach-Mazur distance between \ell_p^n and \ell_q^n is O(\sqrt n). It is also easy to show that d(\ell_1^n,\ell_2^n)=\sqrt n, so \ell_p-spaces hardly improve on the easy lower bound, and do not improve on it at all in dimensions n for which an n\times n Hadamard matrix exists.

In 1981, Gluskin famously solved the problem by determining the correct asymptotics for the diameter of the Banach-Mazur compactum. Informally, what he showed was that the diameter is within a constant of the upper bound that follows immediately from Fritz John’s theorem. If we make the quantification explicit, then the statement we end up with is

\exists c>0\ \forall n\ \exists X,Y\in K_n\ d(X,Y)\geq cn,

where I have written K_n for the set of all n-dimensional normed spaces. (If you want to argue that it is not a set, then let me specify in addition that the underlying vector space is \mathbb R^n.) In words, there is a positive constant c such that for every positive integer n there are n-dimensional normed spaces X and Y such that the Banach-Mazur distance between X and Y is at least cn.

I can’t continue without very briefly describing the beautiful and highly influential idea Gluskin had for solving this problem. He took X and Y to be normed spaces whose unit balls were random symmetric convex sets defined as follows: take the standard basis vectors and a handful of other random unit vectors, as well as the negatives of all these vectors, and take the convex hull. Gluskin then showed that if two normed spaces are chosen from this distribution, then with high probability their Banach-Mazur distance is at least cn.

But back to the main point, which is that the logical form of the above statement is very similar to the logical form of Vinogradov’s theorem, which is

\exists N\ \forall n\geq N\ \exists p_1,p_2,p_3\in P\ \ p_1+p_2+p_3=n

where I have written P for the set of primes. And yet, Vinogradov’s result is unquestionably a theorem, while Gluskin’s result is unquestionably a counterexample, or at least an example.

What is the important difference between the two statements? It seems to be that in Vinogradov’s three-primes theorem the number n plays a more essential role in the statement that is to be proved about the various quantified variables. In Vinogradov’s theorem, that statement is n=p_1+p_2+p_3, whereas for Gluskin’s theorem the statement to be proved is

\dim X = \dim Y = n and d(X,Y)\geq cn,

which we can write equivalently as

\dim X = \dim Y = n and d(X,Y)\geq c\dim X.

In the case of Vinogradov’s theorem, the whole challenge is to get those three primes to add up to n, whereas for Gluskin it is not remotely challenging to get the dimensions of X and Y to equal n: the challenge is to get X and Y to be very far from each other, relative to their common dimension.

There is a further complication to bear in mind here, which is that via the process known as Skolemization, a universally quantified statement of the form \forall x\in X\ \exists y\in Y\ \ P(x,y) can be converted into an existentially quantifed statement \exists f:X\to Y\ \forall x\in X\ \ P(x,f(x)). (For this to be an equivalence one needs the axiom of choice, but it is certainly a sufficient condition.) This is not just a piece of logical trickery, but it often reflects quite accurately how we think about some problems. For instance, it is more natural to think of Gluskin’s example as a recipe for constructing (or at least proving the existence of) a pair of suitable normed spaces for any given dimension n, or in other words to construct a suitable function from \mathbb N to pairs of normed spaces by giving its value at each n, than it is to think of it as a statement that says that every positive integer n has a certain complicated property.

Yet another complication is that some universally quantified statements follow naturally from existentially quantified statements, or may even be equivalent to them. For example, the theorem that a 2-dimensional torus is not homeomorphic to a 2-dimensional sphere is a universally quantified statement (every map from the torus to the sphere fails to be a homeomorphism), but the natural way to prove it is to prove the existential statement that there is an invariant that distinguishes the two spaces. For an example of where a universal statement is equivalent to an existential statement, consider a statement of the form that a vector x\in\mathbb R^n does not belong to the convex hull of a certain compact set A. The statement that no convex combination of elements of A is equal to x is equivalent to the existence of a linear functional \phi:\mathbb R^n\to\mathbb R and a \lambda\in\mathbb R such that \phi(x)>\lambda and \phi(a)\leq\lambda for every a\in A. In both these cases it feels natural to regard the result as a theorem that is proved via an existential statement, perhaps because it is the theorem that is ultimately what interests us. But using “what interests us” as a criterion to determine what counts as a counterexample seems a little vague, and is a difficult criterion to use if we want to explain convincingly why AI should be good at finding counterexamples.

A more general argument against the notion that there is something about existential statements that is particularly suited to AI is that the need to establish existential statements pervades almost all of mathematical research, regardless of the nature of the headline result being aimed for. For example, if I want to prove a statement by induction, I may well look for a strengthening of the statement that serves better as an inductive hypothesis. Or if I want to prove that every object of type T with property P also has property Q, then I may well look for a property R that follows from P and can be used to prove Q. These are more metamathematical existence problems, but the distinction can be somewhat blurred, and more importantly, when trying to prove a statement S, it is often the case that the main question in our minds is less, “Why is S true?” and more, “What could a proof of S be like?” To give an example, I feel I understand pretty well why Goldbach’s conjecture is true — a highly plausible probabilistic model of the primes implies it and agrees closely with computational data — but if I were making a serious attempt to prove it, that understanding, which many mathematicians have had for a century or so, would be of limited help. Rather, my main task would be to try to find proof techniques that were powerful enough to make those heuristic ideas rigorous.

What is the difference between an example and a counterexample?

Logically, every statement of the form \exists x\ P(x) is a counterexample to the universally quantified statement \forall x\ \neg P(x). However, we do not describe all existential statements as counterexamples. For example, if I were to say, “The \ell_p-spaces with 1\leq p<\infty are all separable, as is c_0, but \ell_\infty is not separable,” I would not describe the second part of that assertion as a counterexample to the claim that all Banach spaces are separable. Rather, I would present it as probably the most basic example of a non-separable space. The important point seems to be that there was no particular reason to think that all Banach spaces would be separable, and finding an example of a non-separable space is not very difficult.

I think the first point is more important here: we are more inclined to call an object a counterexample if the existence of that object disproves a statement that we had quite good reason to believe. It often happens that after repeated unsuccessful attempts to prove a statement, mathematicians begin to feel that it has no particular reason to be true, even if it seems to be hard to come up with a counterexample to it. In such a situation, if a counterexample is eventually found, it may have lost something of its “counter” feel. My impression is that the construction of a non-sofic group comes into this category. There have been several proposals in the literature for how one might construct such a group, and I don’t think there were many (or even any?) experts who strongly believed that all groups were sofic. So it feels more natural to say, “OpenAI came up with the first example of a non-sofic group” than to say, “OpenAI found a counterexample to the soficity conjecture” (despite the fact that that section of their paper is entitled “A counterexample to the soficity conjecture”).

Likewise, it seems to me that the new lower bound for multicolour Ramsey numbers is more of an example than a counterexample. I think quite a lot of people believed that the bound should be exponential, so for them it was a counterexample, but others, myself included, were more neutral about it. As a matter of fact, I have worked on the problem in the past (a long time ago) in an equivalent formulation, which asks how many triangle-free graphs on n vertices you need if you want their union to be the complete graph K_n. If you take bipartite graphs, then it’s easy to see that you need \log_2n of them, but that bound can be improved if instead you observe that a complete 5-partite graph can be written as a union of two triangle-free subgraphs, and therefore it is possible to write the complete graph as a union of 2\log_5n triangle-free graphs. It is then tempting to try to do better, with triangle-free graphs that are less dense but that make up for it with unbounded chromatic number — a necessary condition if one wishes to use a sublogarithmic number of graphs, which is equivalent to showing a superexponential lower bound for R(3,3,\dots,3). All this is to say that when I worked on the problem, my efforts were concentrated on what turned out to be the right direction, so for me OpenAI found an example of what I (weakly) expected, rather than a counterexample.

Where does this leave us?

I would like to find a coherent explanation of the conjunction of the following facts.

  1. The most notable mathematical results proved by LLMs have tended to be ones that we would classify as examples or counterexamples, where counterexamples are, broadly speaking, existence statements that disprove statements that we expected to be true.
  2. Many statements can be formulated as existence statements when we would usually think of them as universal statements, and vice versa, so what we consider to be an example depends on the mathematical context of a statement as well as its logical form.
  3. LLMs are pretty good at proving universal statements as well: it’s just that the strongest statements they have proved that we would think of as theorems have mainly not been at the level of the strongest statements that we would think of as counterexamples.

Given these facts, it seems likely that what LLMs are good at is something else, which happens to have as a consequence that they are good at the kind of existence problem that we would normally classify as asking to find a non-trivial example.

Let us consider two things that we can be confident that LLMs are good at. One of them is knowing a lot of mathematics: if a problem can be solved by means of a relatively standard argument, it is highly likely that an LLM will be able to find and use that argument. The other is the ability that an LLM has simply by virtue of being a computer: it can work at huge speed (compared with humans at least) and can therefore afford to make a large number of unsuccessful attempts at a problem before it finds a solution.

Without even looking at what LLMs have actually managed to solve, one might guess that these two features would lead to their having a somewhat different style from human mathematicians. Very roughly, LLMs would have the edge when there is more of a probabilistic element to the proof-finding process: they would be good at problems for which the best method is to try a lot of ideas, not necessarily particularly novel, until at some point you get lucky. Humans on the other hand would be better (for the moment) at finding more “surprising” and “conceptual” arguments, where the appropriate method is to dig deeper and deeper into a problem until the solution reveals itself. (It is hard to say exactly what this means, but I hope that any experienced researcher reading this will know what I am talking about.)

This raises two questions: does the guess above correspond at all to the reality that we are observing, and is there any reason to suppose that what I have tentatively described as the “LLM style” of doing mathematics would lead naturally to LLMs discovering several counterexamples (or just examples) to long-standing conjectures, even if that was by no means all they could do?

I don’t pretend to have a scientific answer to either question, but the reactions of experts to several of the remarkable solutions that ChatGPT has found do lend some support to the idea that LLMs work in more of a try-lots-of-things-till-you-get-lucky way. People often seem to react by saying something like, “Initially I was amazed that the problem had been solved, but on closer inspection I realized that the approach was actually not all that novel, and one that with the right small hint a suitably expert human could have found quite easily.”

For the second question — whether the LLM style is well suited to finding (counter)examples — I think matters are less clear, because there are many ways of searching for a counterexample, and some of them fit better than others the style I have described. Here are a few general methods. (I don’t claim that the list is exhaustive.)

  1. Look for an off-the-shelf example. Here one has a stock of fairly standard examples and one simply tries them out one after another to see whether any of them fails to satisfy the given statement. For example, Ryan O’Donnell ends his wonderful book on the analysis of Boolean functions with some tips, one of which is, “If you have a conjecture about Boolean functions, test it on dictators, majority, parity, tribes (and maybe recursive majority of 3). If it’s true for these functions, it’s probably true.”
  2. Build an example from basic examples and standard construction methods. For an algebraic problem, for instance, one might start with some standard examples, but then take products or quotients or limits.
  3. Make heavy use of metavariables. The word “metavariable” comes from computer science, and in particular from automatic theorem proving, and refers to the practice that in mathematics would correspond to writing, “where x is to be chosen later,” (in which case x is the metavariable). In a paper we usually do this only in fairly simple situations such as when we need to choose a number \epsilon>0 that is small enough for later arguments to work. But when we search for an example of an object x that satisfies some property Q (which may well be a conjunction of simpler properties Q_1,\dots,Q_k), it is often not a good strategy to specify x completely and only then to check whether it satisfies Q. Instead, it can be more fruitful to do almost the opposite: we start by saying virtually nothing about x and simply launch into proving that it satisfies Q. In the course of doing so, we find that we need x to satisfy a property P_1. If we are lucky we can describe in a nice way a very general class of objects x that satisfy P_1. For instance, we may be able to find a parametrized class: we identify some function f and show that f(y) satisfies P_1 for every y of a certain type. The problem is then reduced to finding y such that $Q(f(y))$ holds, which is a more specific version of the original problem. There may be many iterations of this process, or a mixture of this process and other processes, before an example is eventually found.
  4. Try to prove the opposite. If one wishes to find x such that Q(x), it can be surprisingly helpful to start by attempting to prove the statement \forall x\ \neg Q(x). The reason this can be helpful is that using our standard methods of attempting to prove something, we may end up identifying a key lemma that would suffice: that is, we may find an intermediate property R that implies \neg Q in a non-trivial way and thus reduce the problem \forall x\ \neg Q(x) to \forall x\ R(x). Turning things round again, it may well then be that finding a counterexample to R is easier than finding a counterexample to \neg Q (that is, an example that satisfies Q). Of course, there is no guarantee that a counterexample to R will be an example of Q, but sometimes we are lucky and it is. More often, we can use the idea of the previous method, noting that it is at least a necessary condition of an example of Q that it should not be an example of R, so one can try to describe a general class of objects that fail R and in that way reduce the problem.
  5. Successive approximation. Sometimes, when we are searching for an example of x such that Q(x), we write down a moderately plausible guess x_0 not because we think it has a chance of working (if we did, then we would be using the first strategy), but because we hope that if x_0 does not satisfy Q, then we will be able to diagnose what went wrong and specify a new guess x_1 that does not have that defect. Again, this strategy can either be iterated or combined with one or more of the other strategies.
  6. Just-do-it proofs. Sometimes we need x to satisfy infinitely many properties Q_1,Q_2,\dots, each of which is, individually, quite easy to satisfy. In such situations, we often “build” x inductively bit by bit, ensuring at the ith stage of the process that however the building process continues, x will satisfy Q_i.
  7. Pick a random example. Often it is very hard to give an explicit example of an x that satisfies Q, but there is a natural probability distribution for which one can show that if one chooses x randomly from that distribution, then with high probability (or at least non-zero probability) it will satisfy Q.
  8. Pick a generic example. In more infinite contexts, it may again be quite hard to give an explicit example of an x that satisfies Q, but one may be able to show that the set of x that fail Q is or measure zero, or is a meagre set, or is small in some other way.

There is no particular reason to suppose that LLMs would be equally good at each of the methods above. So perhaps what we are observing is not quite that LLMs have a particular ability to find examples, but more that they are particularly good at finding examples (and proofs) in a certain way. Looking at the above techniques, one might imagine that they would be very well suited to checking off-the-shelf examples, finding just-do-it proofs (since that is a rather standard method with lots of instances in their training data), using the probabilistic method (unless, as often happens, significant new ideas are needed to show that the probabilities work out), and picking generic examples. The other three methods described above — use of metavariables, trying to prove the opposite, and using successive approximation — require more of an ability to judge whether the approach one is taking is likely to be fruitful. Here it seems at least possible that humans will sometimes have an advantage, but the conditions that a problem would need to satisfy are quite stringent. One would need an example to be one that lies at a leaf of a very large search tree — too large to be searched for by a combination of moderate mathematical ability and brute force — but that can be found by a mathematician with a sufficiently good nose for when they are making progress that they can prune the search tree very substantially.

Why wouldn’t LLMs also have that “nose”? I don’t rule out that “nose” is an emergent property of the way LLMs are trained, and that within a year or two they will have it to the same extent that we have it. But for now, in my interactions with ChatGPT, I do have a distinct impression that they haven’t got there quite yet. When I discuss an open problem with 5.6 Pro, I am often presented with approaches that sound promising until I think about them carefully, and then seem quite a lot less promising. And they will also often end a response by saying, “I have not managed to answer the question you asked, but have managed to reduce it to the following much narrower and more precise question,” which sounds very promising until it has happened five times without any obvious progress having been made. It isn’t completely obvious how they will get better at this, since their training data will not be full of examples of fruitful and less fruitful directions to pursue when trying to solve problems: all they will typically see is tidied up proofs that hide the thought processes of their discoverers. Of course, human mathematicians also don’t get to learn much about how to do research from the experience of other mathematicians, and yet we somehow manage to pick it up. But the situation is a little different for us, in that a lot of what we learn is by doing rather than emulating.

Another reason it is not obvious that “nose” is a property that emerges naturally when LLMs are scaled up is that if LLMs make heavy use of their broad knowledge and can afford to do a lot more brute-force search than humans can, then they will lack the incentive that humans have to prune the search tree ruthlessly. It could conceivably be that their successes so far are achieved using methods that for a human would be considered extremely inefficient, but that because of their superior speed and knowledge, the combinatorial explosion these methods will lead to has not yet become apparent.

It would be very interesting to try to test this experimentally, but it is also difficult, because if an LLM has what looks like the kind of idea that could only be the result of “deep thought” about a problem, we can never be sure that it has actually carried out that deep thought, as opposed to finding a model argument already in the literature, or in other words exploiting the deep thought of a human mathematician. It would probably be easier (but still not easy) to test it by using models that are less powerful than the latest ones and that have been to some extent shielded from the mathematical literature: one could give them a carefully designed suite of problems and see whether the ones that the LLMs solve have particular characteristics.

It may seem as though I am desperately clinging to the hope that humans will continue to be able to make meaningful contributions to mathematical discovery for a while yet, but while I do indeed hope that, I am not making any assertions of the form “LLMs will never be able to do X”. I think it is likely that they will, and given the pace of progress over the last three years it will probably happen quite soon. But I do think that there may be a hurdle for LLMs to clear and it seems at least possible that it won’t be cleared as straightforwardly as some of the previous hurdles.

In that connection, it would also be interesting to see whether a different reward structure leads to LLMs being able to solve different kinds of problems. For example, if during training an LLM (or machine-learning system of some other kind) is not just rewarded if it ends up with a solution, but also penalized if it explores too many dead ends or if it “cheats” by getting the answer from the literature, perhaps it would be incentivized to go about the research process in a more human way and thereby achieve better results for classes of problems where it is yet to make a big impact.

If the hurdle is cleared, either by pure scaling up or by some more thoughtful method, it will be quite difficult to know when that has happened, since, as just mentioned, an idea that seems very original and surprising may just be lurking somewhere in an LLM’s training data. But I would be confident that it had been cleared if an LLM were to come up with a proof that was as surprising to me as the solution of the cap-set problem was in 2016: the previous best known bounds were completely eclipsed, the method was utterly different from anything I had thought about trying, and afterwards there was a flurry of activity as people came to understand what this wonderful new technique was capable of.

Conclusion

I wasn’t quite sure where I would end up when I started this post, and now that I’ve got to the end, I feel that my main conclusions are not particularly new or surprising, but I hope that the route to them is of some interest. The main points I have made are the following.

  1. “Finding an example” is in practice not the same thing as proving a statement that begins with an existential quantifier.
  2. If it is true that current models are particularly good at finding examples, that is probably not because they have a particular affinity for existential statements, but more because the proof-discovery methods that are appropriate for finding certain kinds of examples play to the obvious strengths of LLMs: wide knowledge and the ability to explore many paths of the search tree that humans would judge to have a low probability of success.
  3. It seems likely that LLMs will carry on improving very quickly. However, if, contrary to expectations (mine at least), there turns out to be some residual class of problems (or other mathematical activities) for which humans continue to have the edge for a while, it is likely that those will be problems for which the mysterious human ability to prune the proof-discovery search tree is particularly advantageous: that is to say, problems where the search tree is deep and has a large amount of branching, so that without rigorous pruning a search is not feasible even for a computer.
  4. A good sign that LLMs have reached human level for a much wider class of problems will be if they start proving theorems using methods that, like much of the very best human mathematics, are new and surprising but that with hindsight come to seem beautiful and natural. They should also be methods that are difficult to stumble on by accident. It is hard to say precisely what would count as such a proof, but I think we’ll recognise it when we see it.

July 29, 2026

Secret Blogging Seminar — An experiment with AI-assisted writing

As in David’s most recent post, there’s been a lot in the news about finding proofs and counterexamples with AI. Last weekend, I decided to try an experiment with writing using AI. I learned a lot, and wanted to quickly discuss the experiment and my thoughts on it here. Lots of people are certainly already doing this, but I haven’t seen many people talking about it.

The starting point is that Victor Ostrik and I started a project back in 2017, generalizing a result of Kuperberg about quantum G2, from generic q to q a root of unity. Namely, we showed that for q a root of unity outside of a specific finite list, the Karoubi completion of the G2 spider category is equivalent to the category of tilting modules of the Lusztig form of the quantum group G2. At some point during those 9 years, we did a little bit of writing, and at some point I gave a talk on it, but otherwise we did very little writing. This was not for mathematical reasons, but rather for executive function reasons on my end, the global pandemic, and both of us becoming directors of graduate study. This suggested an interesting challenge: could I use LLMs (specifically ChatGPT 5.6 Sol work mode mostly at “very high” intensity, via IU’s “Edu” subscription) to write this paper that was essentially mathematically complete, but almost entirely unwritten, and how quickly could this be done. To some extent this was a free experiment, because realistically I don’t think we’d have ever finished the paper at this point, and so it’s not replacing a bespoke paper that could have existed.

After spending a decent chunk of the time from Saturday until now on it, I now have a draft that I’m pretty happy with. I want to emphasize although mathematically this is Victor and my joint work, and although Victor has allowed me to make this post, he has not signed off on the accuracy and all errors at this point should be blamed entirely on me. Also my work is supported under NSF DMS grant 2000093 and Simons Foundation grant MPS-TSM-00007608.

Ok, here’s what I did:

  1. First, I asked if Sol could one-shot the main theorem. The answer was yes, though for a somewhat simple reason: Bodish-Wu write “It is possible to adapt the approach from [1], which itself is based on [7], to prove that the Karoubi envelope of [the G2 web category] is equivalent to the category of tilting modules as long as $[2], [3] \neq 0$.” That is to say, Elijah already proved the same result for C2, and a similar argument will work for G2. So the robot supplied the similar argument. I asked it to write that argument up, and then to check it over for good references and to read it like a referee would and make edits. This took around 30 minutes. Here’s the resulting file.
  2. Second, I uploaded my talk slides (and the tiny file already written, which was mostly useless), and asked Sol to give a proof of the main results following the slides. Again I asked it to edit it. This took around 30 minutes. Here’s the resulting file.
  3. Then I looked at the files. As mathematical exposition, I consider both to be garbage.
  4. Then I spent several days giving feedback attempting to improve the second file based on my talk. At no point did I edit the source directly. Most of this was in what I would call the style of a (low executive function, see above) PhD advisor. That is, I would kinda skim the file, get annoyed about something, and tell it to fix it. While it was fixing the paper, I would skim some more to try to find something else that annoyed me. This was a long process! It took three days, nearly 100 prompts, 10-15 hours of reasoning, plus another 10-15 hours of non-reasoning computer time. This used nearly an entire week of my generous budget, and Sol estimates that this would cost around $100 (within a factor of 2) at metered rates. Eventually I got to a version of the paper that I’m pretty happy with. Here’s the resulting file.

I thought I’d distill some thoughts and some questions from the process, I’m of course very curious for your thoughts on the matter.

Comments:

  1. This was much faster than I could have written the paper myself, though slower than I thought it would be. I think the final product is comparable in quality to a typical math paper of mine. On the other hand, I think that compared to my fastest writing collaborators it was not orders of magnitude faster, and the quality is not close to the output of the best mathematical expositors. AI at this point is much worse at writing paper than finding counterexamples to conjectures.
  2. In this case, I was not very worried about errors, because I already had thought through the whole argument and was highly confident that it would work (modulo getting the exactly correct list of exceptions). Nonetheless, I felt like Sol did not make errors more frequently (or of a worse character) than I would expect of myself or a collaborator. Most errors were stuff like “Oh, forgot to check whether this theorem actually works at all roots of unity.” This is typical of my experience with 5.6, which is dramatically better at doing math accurately than previous ChatGPT models.
  3. In this case the vast majority of the ideas were already present from Victor and my work. In particular, the goal was not just to write a proof, but to write our specific proof. Nonetheless, I do think the model contributed mathematically in one key way: in my original sketch I always worked over each q individually, and the model preferred to work integrally, and this resulted in some very nice simplifications in Section 4.1. If and when we turn this into a real preprint, I will include a brief discussion of the intellectual contribution from the model.
  4. I was surprised when I printed out and read a near-final draft, that this feels to me like a paper I wrote. That is the voice is not different enough from what I would write with a human collaborator to feel like it’s not in large part mine.
  5. The experience is disconcertingly similar to advising a PhD student on a paper. That said, a PhD student would need less handholding on their second paper, but an LLM won’t really learn.
  6. I was surprised about how important “prompt engineering” remains, and I think that if I were to write another paper this way I would be able to write it faster and better. The key points are that the model is lazy and easily distracted (both properties I find highly relatable!). It’s lazy in the sense that if you ask it to do a lot of work all at once it will take shortcuts and not do a good job. At one point I had to be like “no, go look at exactly how I made TikZ diagrams, now make all your diagrams actually good like that.” It’s easily distractible in that if you’re not clear about the scope of your question and the document is long, it will start spending crazy amounts of time doing who knows what. Like it wrote the whole first draft in 20 minutes, but then when the paper was 50 pages long, I asked it to switch the order of two paragraphs and it took an hour. Make clear requests and not too many requests at once. Form a plan first and then implement the plan. Be specific about whether it should be editing the document, and if so in which sections. For simple tasks, medium intensity is better than very high.
  7. Starting again from sketch, I’d try to follow Terry Tao’s advice for writing and start with an outline and gradually flesh it out, rather than trying to start with a one-shot paper and then editing.

Questions:

  1. To what extent is this final paper adding any value to the original talk? Especially considering that readers themselves could use an AI model to flesh out points in the talk that they didn’t understand? Maybe we should just be focusing on talk-length digests and formal checking, rather than traditional papers?
  2. What should we do with this paper? I don’t want to make someone hand-referee it, because it doesn’t seem fair when it wasn’t hand-written. Probably we will put it on the arxiv once we’ve human-checked it fully and Victor has signed off on it, so that other people can use the results if they need to.
  3. Given the speed-up, when does it still make sense for me to write papers by hand? (Relevant here that I’m a very slow writer and don’t really enjoy it, the way I enjoy say preparing and giving a talk.)
  4. What does this mean for PhD advising? Many PhD students need a similar amount of guidance to what I gave the model in this project. But you can now remove the student from the loop (either intentionally, with the advisor just writing using LLM assistance rather than having students, or unintentionally, with the student just feeding all the suggestions to an LLM and reporting back to the advisor).
  5. Have any of you done better with AI-assisted paper writing? My points 6 and 7 above sounds like something where someone is going to say “blah, blah, scaffolding, blah, blah, multi-agent…”

What a strange world to live in…

July 26, 2026

Tim Gowers — Thoughts about the Leiden Declaration

Last September I went to a workshop at the Lorentz Centre in Leiden to discuss mathematics and AI with historians, philosophers, computer scientists, AI researchers, and mathematicians of several different flavours (though there was a surprising preponderance of algebraic geometers). The whole event was extremely stimulating, with some talks but also a lot of time set aside for discussion. One of the concrete outcomes of the workshop was the Leiden Declaration, which has now been signed by over 3000 people. Given that I was part of the workshop, it might seem a bit strange that I am not one of the signatories of the resulting declaration. The reason is not so much that I disagree with it in any concrete way, but more that in several places it makes confident assertions and recommendations that I feel somewhat uncertain about. So instead I prefer to try to articulate my views about the issues raised by the declaration and put them in this blog post. Before I do that, I would like to make clear that I am very glad that the Leiden Declaration exists and I think that it has done a lot of good in focusing people’s minds on the issues that AI is forcing the mathematical community to grapple with, which are more acute now than they were last September.

Let me begin by quoting a passage from the declaration that sets out “what we take to be characteristic values of mathematical research that we have a joint interest in preserving”.

  1. There are many reasons to pursue mathematical research, ranging from intellectual curiosity to a desire to solve practical and societal problems. Underlying much of mathematics is the activity of proof. Mathematical proofs are regarded as conferring the highest degree of certainty to their conclusions, as well as imparting understanding of why their conclusions are true. These characteristics of proof support the scientific integrity of mathematics.
  2. Results are attributable to specific authors who take credit for their discovery and assume responsibility for their correctness. These principles ground the merit-based standards to which we aspire in mathematical research.
  3. Mathematical arguments are regarded as transparent and subject to independent verification. They may be extremely long or difficult, but in principle no proprietary knowledge or equipment should be required to understand them.
  4. Mathematicians share a concern for proper evaluation of mathematical work relative to shared standards of depth, difficulty, and significance.
  5. Mathematics produces not only a body of results, but also understanding, clarity, and judgment among the communities of mathematicians who have shaped them, often in the context of their own autonomously guided research. This expert knowledge is essential, both to effectively use mathematics, and to continue to articulate new and significant research questions. A key source of strength of the discipline has long been the autonomous shaping of the direction of research and the methods used to pursue it.

The first thing I would say about these values is that they are undoubtedly values that are widely held by mathematicians, including, with some qualifications, me. The main qualification I have concerns point 4: I find the notion of “proper evaluation” somewhat problematic, given that different mathematicians can have very different judgments without either of them being clearly wrong, especially when it comes to the significance of a piece of mathematics. Also, these judgments are used for purposes such as the acceptance of papers in journals, hiring and promotion decisions, the awarding of prizes, and so on, that are part of a system that copiously rewards a few people — I myself have hugely benefited from it — but doesn’t necessarily adequately reward a lot of people who are doing less visible work that is essential to keeping the whole enterprise going.

But the more important point is whether these values are ones that we should fight for in the future, as the Leiden Declaration suggests. I find that clearer for some of them than others. For example, it seems to me that the importance of rigorous proof will be even greater in an AI age than it was before — if the output of AI is not underpinned by rigorous proof, then the kinds of difficulties one already hears about with certain areas of human mathematics (see for example many talks by Kevin Buzzard arguing for the value of formalization) would be hugely magnified. But what about the attribution of results to specific authors, who take both credit and responsibility for them? Suppose that at some point in the future AI becomes more autonomous, reading the literature and solving many problems that it finds. Suppose also that its solutions are autoformalized, so there is no serious doubt about their correctness. In such a situation, there would be nothing for a human to take credit for or responsibility for. Does that mean that we should declare such results undesirable and threatening to mathematical values?

Of course, something could well be missing in such a situation: perhaps the proofs would be badly written and hard to follow, which would mean that they lacked something we all very much value. So let me extend the thought experiment slightly. What if by that stage one could take one of these outputs and ask an LLM to explain the ideas, and what if LLMs did a very good job at that? That is not particularly hypothetical, since they are often pretty good at this job already, but I am imagining a world in which they are much better than they are now, as they will presumably become.

So now we would have a world in which a lot of problems had been solved, we were sure that the solutions were correct, and we had an LLM ready to explain those solutions in as much or as little detail as we wanted. Is that a future we should resist, and if so, why?

One obvious reason is that it would take a huge part of the fun out of the subject. It is extremely satisfying to struggle with a mathematical problem for months or even years and eventually solve it. But I worry about that argument, because it seems to be saying that we should resist doing mathematics the easy way because a tiny fraction of the world’s population gets huge pleasure from taking orders of magnitude longer to do it. That is not to say that I wouldn’t be sad that a way of life that has sustained me for the last forty years was not available any more — of course I would. I just find it hard to use it as a reason to argue that we should try to preserve the “ownership structure” of mathematical results. If we arrive at a world where mathematical theorems are no longer associated with mathematicians, maybe that won’t be any more problematic than the fact that stars aren’t named after astronomers and most aren’t named at all. I’m not necessarily in a hurry for that world to exist, but maybe once the transition had happened, people would be OK with it.

The third value I share in an uncomplicated way, and I have already discussed the fourth. The fifth value is one that I hold very strongly, though I’m not so keen on the idea of experts consciously “shaping the direction of research”, something that I see as happening more organically. Obviously there are some notable examples of mathematicians who have created wonderful programmes of research, but even there I would like to credit other mathematicians with understanding what is wonderful about those programmes and contributing to them enthusiastically as a result, rather than being told what direction to pursue and meekly doing so (which is probably not what the declaration is actually trying to suggest, but it has a slight flavour of that for me).

But that’s a minor quibble when set against my main worry about the effect of AI on mathematics, which is the possible destruction of mathematical culture. There is at the moment an extraordinary body of knowledge and expertise that exists not just in the mathematical literature but in the heads of mathematicians all round the world. Imagine if AI didn’t exist and a pandemic broke out that for some reason wiped out all mathematicians and nobody else. All the literature would still be there, but nobody would have the faintest idea what to do with it. To revive a mathematical tradition under those circumstances would be extremely difficult and take decades. Now imagine a slight variant of that, where AI does exist and because of it people are no longer motivated to put in the years of effort it takes to reach the level of expertise that a typical research mathematician has now. After a decade or two, we might arrive at a situation where the mathematical literature has, in some form, been vastly expanded, but there is no corresponding community of human experts who have a shared understanding of parts of it. Almost all of mathematics would be like the areas that we have more or less forgotten about today, areas that exist in papers written many decades ago that nobody reads any more. (I won’t name any such area because I don’t want accidentally to suggest an area that many people still love and work on.)

This, it seems to me, is a possibility that we should try very hard to resist, but I agree with many other commentators who say that in order to resist it, we will need to give less priority to some of our current values — and I would include ownership of mathematical results in that list — and more to others. For example, if Person A gets an LLM to one-shot a solution of an important open problem (which is formalized, possibly automatically, so there is no doubt about its correctness) but Person B makes the effort to digest the solution and explain it in a way that other mathematicians can understand and learn from, then I think we will want Person B to get the lion’s share of the credit. The credit would be of a slightly different from what it is now, which could be described as admiration for somebody’s talent, insight, speed (I mean here the purely factual statement that speed is often admired — I would prefer that to be less the case) and hard work. It would be more like the gratitude that one feels already for somebody who writes a beautiful textbook that makes a whole area of mathematics coherent and accessible.

Maybe that is what the “research mathematicians” of the future should do: make a selection from a vast sea of AI-generated mathematics and write a book about it in such a way that other mathematicians can read the book and feel the kind of enrichment that we feel when we get to grips with an area of mathematics.

At this point I have to admit that there’s a pessimistic side of me that asks the following general question whenever anyone says anything about what the role for humans might be in the future: why do you think that AI wouldn’t be able to do it? For example, with the suggestion I’ve just made, what reason is there to suppose that ChatGPT 8.2 wouldn’t be able to have a short interaction with you about your mathematical tastes and background and then write the ideal textbook just for you? Humans are likely to be better at this kind of curating for a little while yet, but is it a fundamentally human ability that AI could never hope to emulate?

In a world where AI wrote bespoke textbooks (or more likely, just taught people in some more direct way), something would be lost that feels important: mathematics as a collective endeavour. If we all just learnt cool bits of maths for our own private satisfaction, we would miss the considerable pleasure that comes from discussing mathematics with others, though even that could in principle be restored by a benign LLM that deliberately taught many people the same cool bits of the subject, though an LLM that could do that sort of social engineering would raise all sorts of safety issues.

Let me now turn to the section of the declaration about potential threats. I’ll put my comments on each one in square brackets.

  1. Current automated techniques can produce plausible but unreliable (or even incorrect) arguments which are difficult to distinguish from correct mathematical proofs. This applies not only to informal arguments, but also to formalizations, where the difficulty lies in the translation between computer-encoded and human presentations of concepts. These fast-moving developments put our present system of review under increasing pressure, jeopardizing our ability to implement traditional standards for the correctness, transparency, and independent verifiability of proof. [This feels like less of a problem now than it did last September, partly because the best LLMs hallucinate a lot less than before, and partly because autoformalization is improving all the time — I have just used harmonic.fun’s Aristotle system to formalize a complicated paper in Lean and I didn’t need to know any Lean to do it.]
  2. Technologies that draw extensively on the published mathematical commons undermine the traditional system of attribution. Models trained on published works frequently return outputs that do not properly cite the human works they synthesize. Many current models are also built on data obtained by systematically exploiting licenses and access arrangements that were not made with artificial intelligence in mind, or indeed by simply violating copyright protections. [This is a problem at the moment, when ownership of results is important, and I am very much in favour of people making an effort to give appropriate credit for mathematical ideas that AI may have used. However, in the longer term, as I have already discussed, I think this ownership structure will break down and the issue will become less important. It also seems possible that LLMs will become better at revealing their sources.]
  3. Technologies which affect the way in which mathematics is practiced may disturb the current system of incentives. The use of artificial intelligence — and thus also the sort of problems which it can address — may become incentivized for its own sake, disrupting our mechanisms for hiring, funding, and recognition. This disadvantages researchers who do not have access to the technologies or decision-making related to them, or who are unwilling to use technologies controlled by organizations whose values they do not share. [These seem to me to be genuine problems. I think there is simply no point in hoping that our current system of incentives will not be disturbed — it obviously will. I am not necessarily too worried if our mechanisms for hiring, funding and recognition are disrupted, as I don’t find those mechanisms unproblematic as they are, but disadvantaging researchers who do not have access to good LLMs is something I certainly think we should worry about.]
  4. Proper evaluation is endangered if results are communicated through informal channels such as press releases or blog posts, often without any research paper or other disclosure of information necessary for scientific evaluation. This practice seeks publicity for new results on market timelines before the accepted processes of community evaluation in mathematics can take place. In many cases this leads to simplifications in reporting, such as overemphasizing the significance of automated tools and undervaluing the prior human contributions which have made those tools possible. Such oversimplification risks influencing public opinion in a way that not only damages perceptions of mathematics, but also misleadingly uses specific mathematical tasks as metrics for the general reasoning capacities of commercial products. [I think this can be a problem, but I think it is not as serious a problem as some of the others, since when results get overhyped, there seems to be no shortage of people publicly (and rightly) pointing that out.]
  5. These developments put the autonomy of mathematics under threat. The increasing involvement of technology companies in mathematical research raises the risk that research questions may come to be prioritized because of their amenability to automated mathematics, rather than expert judgment of their deeper significance. Indeed, broader understanding of the field may be permanently lost in the process of automation. With university budgets under pressure, this reshaping also changes professional incentives in a manner which encourages the collaboration of researchers with technology companies on asymmetric terms. If left unchecked, these trends go beyond threatening researchers’ autonomy, affecting the scope and depth of mathematical research itself. [I think this could be a problem, but it also seems to me that mathematicians have a lot of power here. For instance, if a technology company were to produce a lot of research that mathematicians did not find all that interesting or important, I don’t think they would be able to use their financial and other resources to persuade us to change our minds. Rather, what seems to happen is that mathematicians say, “Yes that does X but it doesn’t do Y,” and the tech companies then feel challenged to do Y.]

There follow eleven recommendations for individual mathematicians. I agree with almost all of them. The one that I’m not so sure about, for reasons I’ve basically already gone into, is this.

Affirm the humanity of authorship. Credit and responsibility continue to belong to humans within the mathematical community and should not be given to automated systems. Artificial intelligence may obscure, but does not replace, the collective human labor behind a result.

I’m not sure what that really means. For example, should we affirm the humanity of authorship in the case of the solution to the unit-distance problem? Some humans did a wonderful job of explaining the proof that OpenAI’s model came up with, and the model made use of some highly non-trivial mathematics produced by humans, but the solution itself has not been credited to any human, and nor should it be in my view.

Under recommendations for mathematical organizations and not-for-profit research funders I again agree with several of them but have my doubts about some. An interesting case is the following.

Protect the rights of authors. Automated mathematics presents new challenges to the rights of authors, and societies should be proactive in the development of sample licensing agreements to protect these rights. In particular, material should not be used as training data without consent, and publishing agreements should allow authors to opt-out [sic] of the use of their work in this way.

This recommendation seems to belong to a world in which journal articles are the main means of dissemination of mathematics. But that has long since ceased to be the case: almost all dissemination now takes place via arXiv preprints, with journals limited to providing a little extra mark of prestige. Once an article is on arXiv, it is on the internet and one can hardly ask for it not to be used as training data. So this recommendation, if it applies at all, will apply to a tiny fraction of articles that are published without first appearing on arXiv. More generally, what right of an author is being compromised when an article is used as training data? We don’t object if human mathematicians use our articles to help train themselves to become better mathematicians — indeed, we will typically be delighted that somebody else thought our articles worthy of their attention. So the objection to a machine doing the same would have to be that for some reason one did not want machines to get better at mathematics in a similar way. I can imagine grounds for such a wish: perhaps somebody is worried about the threat that LLMs pose to traditional mathematical practice, or perhaps they worry that mathematical ability of LLMs will transfer to much more dangerous reasoning ability. But there’s a more complicated discussion to be had here than one might think from reading the recommendation.

The next recommendation is this.

Insist on appropriate publication outlets. Demand that mathematical results continue to be published in peer-reviewed venues such as journals, proceedings, and books. Informal mechanisms such as press releases or blog posts can provide a valuable supporting role, but they cannot replace peer-review or community scrutiny.

For reasons that I’ve gone into many times, I am not too fond of the current publication system, so I can’t get behind this recommendation. Indeed, if the current system becomes unsustainable because of a flood of AI-generated and AI-aided content, I would regard that as a beneficial consequence of AI. However, that doesn’t mean that I would advocate a total free-for-all. I’ve already said that one of my worries is that if mathematical content is not sufficiently organized, then the traditions that we all value could die. I just think that what we will want to do to preserve those traditions is likely to be a lot more innovative than clinging on to the peer-reviewed journal system.

I have highlighted in this post the parts of the declaration that I have doubts about, either because I disagree with them or, more typically, because I sort of half agree with them but want to add many qualifications. That may make the post come across as rather negative, but that is not my intention. The parts I disagree with are in the minority, and I think it is important that a declaration such as this should be made. I should also make clear that my views are evolving all the time, largely because the speed of progress of LLMs has taken me by surprise, but also as a result of conversations I have had or opinions that other mathematicians have expressed online.

I’ll end with two further clarifications. The first is that it may seem as though I am taking it for granted that LLMs will soon be better than humans at all aspects of mathematical problem solving, and maybe also problem posing, theory building, formulation of definitions, etc. I do think all that will happen at some point, but whereas some people say that it will obviously happen within the next two to three years, I would say that it might happen as soon as that, but I don’t rule out that we’ll get lucky and find that we can do interesting AI-assisted maths for quite a bit longer than that before AI doesn’t need us any more.

The second is that I think I have acquired a reputation as somebody who celebrates what is going on. But if, for example, I post on Twitter saying that such-and-such an AI solution is a remarkable development, the word “remarkable” is meant to indicate no more nor less than that I found it very surprising. My feelings about the possibility of AI solving all sorts of problems that interest me are much more mixed. I’ve had the experience twice now of seeing GPT 5.6 Pro one-shot a solution to a problem that I very much liked and had thought about hard (in both cases with much younger collaborators, who, with my approval, were the ones who prompted the LLM). It felt very strange and not particularly pleasant to have the rug pulled out from under my feet like that. On the other hand, I was quite pleased to see the problems solved. It’s actually a similar feeling to the one I have had many times when a problem I am fond of and have thought about gets solved by another human mathematician.

Another factor for me is that I have invested a lot of thought into automatic theorem proving of a more traditional kind. One of my main motivations for that was the hope that the work I put into it would extend the state of the art, measured by which problems a computer can solve. That ship has sailed now, and that saddens me. I still think that there is value in the work that I and my group are doing, but it has become a tougher sell.

So I personally have already found AI quite disruptive, and this is just the beginning. I would have preferred the developments to happen at a slower pace. But I don’t see any practical way to slow them down, so the best we can do is probably to face up to the changes that are being thrust upon us and do what we can to maximize the benefits and minimize the damage. The Leiden Declaration may not be perfect, but it makes an important and positive contribution to that effort.