Musings

BaBar is reporting the observation of a narrow $J^P=0^+$ resonance of mass 2.32 GeV/$c^2$. I haven’t looked at the paper, but this sounds very strange. It decays into $D_s^+ \pi^0$. But it’s well above the (combined) masses of the charm and strange quarks. So it can’t be an ordinary meson. They suggest the possibility of a $qq\overline{q}\overline{q}$ exotic.

My, but this blog has taken a techno-geeky tilt…

Anyway, Phil Ringnalda recently objected to serving XHTML as application/xhtml+xml. He wants to serve XHTML because he uses XML-parsing tools in his back-end. But what, Phil asks, if someone posts a comment which is ill-formed XML? Mozilla won’t render it when served as application/xhtml+xml. So he wants the “safety net” that serving up text/html provides.

Never mind that ill-formed XML will cause his back-end XML parser to barf just as surely as it will Mozilla. No, the real answer to the problem of invalid XHTML in comments is, to paraphrase Ronald Reagan,

Trust, but validate!

So, with the help of a patched version of Alexei Kosut’s MTValidate plugin, we make sure that comments posted to this blog are valid XHTML before they get posted.

This won’t stop a malicious poster from sneaking invalid markup onto this blog (there are steps I could take to deal with that, but let’s just say I’d rather not go there), but it should deal pretty well with inadvertent breakage.

Next objection?

Update: Squashed a small bug, where the Validator would send invalid output (!).

A while back, Evan Goer said of this blog that

Jacques Distler may well be the only person on the planet who understands the XHTML 1 specification and uses it properly.

While flattering, this is surely hyperbole. There are plenty who understand XHTML much better than I. And I don’t believe that people can’t do XHTML properly. Most people simply don’t need XHTML. So there’s no incentive for them to do it right.

If they use it anyway, it’s probably a matter of Geek-chic. Slapping an XHTML DOCTYPE on your weblog is like wearing sunglasses at night. It looks cool! But isn’t necessarily very functional.

Anyway, true to his scientific training, Evan decided to test the quality of the XHTML “in the wild”. He decided to focus on the weblogs of the “Alpha Geeks” — the programmers, web-designers, and web-standards advocates — who are, surely, the most hip, Standards-savvy, knowledgeable folks around. If anyone can do XHTML right, they can.

The results of his survey of 119 Alpha Geek XHTML websites was pretty dismal. Only one site passed his 3 tests (he decided not to apply his 4^th, somewhat subjective, “Why Are You Doing This?” test) and a startling 74% didn’t even have a main-page which validated.

So, what should we conclude? Wearing sunglasses at night is not only useless, it can be downright dangerous.

Today is Yom haShoah, Holocaust Remembrance Day.

In honour of the day, I’m putting up a link to this page which I created in the summer of 2001. It was my first foray into QuickTime Streaming Video, and was done in honour of my father, who’d passed away the year before. Those who survived are aging and soon will be gone. Their voices will fade from our collective memory. And little tales of heroism, like this one, will be lost.

So here’s my small act of preservation. If you have some time (and have QuickTime installed!), put your feet up, click play and give it a watch.

I was very puzzled by Phil Rignalda’s recent complaint about Trackback AutoDiscovery, and I said as much. But then (ironically, by reading a trackback on his post), it occurred to me that perhaps the problem wasn’t AutoDiscovery, but leaches.

The subject of Marcus’ (and perhaps Phil’s) concern was gratuitous trackback pings sent to “A-list” blogs by folks hoping that the resulting trackback link would drive some traffic back towards their own site. If that’s the problem then, of course, AutoDiscovery has nothing to do with it. The “leaches” would send their pings manually, if necessary.

If leaches (as opposed to inadvertent gratuitous pings) are the problem, then perhaps the solution, as Marcus suggests, is to refuse trackback pings from repeat offenders. Whether this is a “feature” of the blogging software, or simply done using .htaccess rules doesn’t really matter much.

Update: There’s also a discussion of these issues going on over at Adrian Frost’s blog. Since he didn’t trackback us, let’s trackback him. ;-)

I’m somewhat confused as to what to make of the recent paper by Hertog, Horowitz and Maeda.

The physics they claim is rather strange, so let me set the stage a bit by recounting (as best I can reconstruct it) the mathematical background.

Seems I’m on a Standards rant. Following on Evan Goer’s musings on the widely-held sentiment that the W3C’s recent work is too hideously complex for mere mortals, I read Joe Gregorio’s argument that this brittleness and complexity is bad for innovation

The web is for, and written by, humans. If we want to see the webs historical wild growth continue, it shouldn’t be choked off with machine-legible-only formats.

I 'spose I should be taken out and shot for using MathML — the epitome of machine-readable markup. But, if you could only see the source from which it’s generated, you’d find that perfectly pleasantly human-centric. Sorry if it had to go through the meat-grinder.

On the other hand, Gregorio seems to like the unstructured gobbledygook that is CSS.

You may have noticed I left CSS out of the mix. That’s because I believe CSS is very amenable to “view source”. That is, if you want to get up and running and don’t know anything about CSS or HTML, if you viewed the source for a web page and saw ‘background-color: blue’, you have a good change of figuring out what’s going on.

I don’t know. From my own experience (I had no prior knowledge of CSS before I started this blog), no one is going to figure out the CSS2 box model, or the difference between class and id selectors, by ‘viewing source’.

Indeed, quite the opposite. Except for the MathML bits, I think that the XHTML source of this blog is imminently human-readable, whereas the CSS stylesheet looks like the raccoons got into the trash again.

AP: I mean, should we outlaw homosexuality?

Santorum: I have no problem with homosexuality. I have a problem with homosexual acts. As I would with acts of other, what I would consider to be, acts outside of traditional heterosexual relationships. …

[snip]

AP: I’m sorry, I didn’t think I was going to talk about “man on dog” with a United States senator, it’s sort of freaking me out.

Senator Rick Santorum: alway one to raise the tenor of the debate. Read the rest of his scandalous interview with the Associated Press.

If I’m going to be The Lone Man, I can’t very well let bozos who stick control-characters (hex 80 to 9F) in their RSS feeds spoil my validation, now can I?

I patched the mt-rssfeed plugin to strip control characters. Don’t know why I didn’t squash this bug earlier.

Update: A better solution is not to muck with the mt-rssfeed plugin itself, but rather to apply my StripControlChars global text filter plugin to its output.

I don’t know whether to laugh or cry. Honestly, this stuff is not as hard as it looks!

But, on one point, I have to disagree

Note that Distler’s site comes awfully close to failing the MIME-type test. Distler is serving up his pages as application/xhtml+xml to all browsers that support it (such as Mozilla) and text/html to browsers that don’t, such as Internet Explorer. According to the specification, XHTML 1.0 documents “MAY” under certain circumstances be served up as text/html, but XHTML 1.1 documents “SHOULD NOT”. To wit: “In particular, ‘text/html’ is NOT suitable for XHTML Family document types that adds elements and attributes from foreign namespaces, such as XHTML+MathML.” But we’ll give him a pass on this one.

That’s just wrong. Graceful degradation (together with a warning label that MathML posts won’t render correctly in inferior browsers) is the correct behaviour. Having this blog not render at all in Internet Explorer (or Opera or Camino or Safari or …) is incorrect behaviour, whatever the “Standards” may happen to say.

The New York Times reports on Grisha Perelman’s papers (I, II) which claims a proof of Thurston’s Geometrization Conjecture, and hence of the celebrated Poincaré Conjecture.

The Poincaré Conjecture, you’ll recall, is the statement that any compact, connected, simply-connected 3-manifold without boundary is homeomorphic to $S^3$.

Perelman’s proof involved proving properties of the “Ricci flow”

which you’ll recognize as the 1-loop renormalization-group equation for a nonlinear $\sigma$-model on this manifold. The idea is to study the long-time behaviour of this flow (perhaps after repairing some singularities which might form — in finite time — locally on $M$ and after a suitable rescaling of the overall volume of $M$).

I don’t understand any of the details, but if someone who does would like to chime in, that would be very cool!

Update: Paul Ginsparg pointed me to this pretty review by Milnor on the history of the Conjecture.

In a previous rant, I complained that cookies were broken on this blog. I was angry enough that I was willing to blame the problem on anyone from the W3C to Saddam Hussein to Bebe Rebozo.

Well, turns out that it really was a longstanding bug in Mozilla. I don’t know whether my complaint, had anything to do with it, but within hours, a patch was posted to Bugzilla and after a long back and forth, has finally landed in the CVS tree.

So, tomorrow, you’ll be able to grab yourself a copy of the latest nightly build and enjoy the return of cookies and a working “rememberMe” script to this blog.

Tonight was my night to prepare the horseradish.

The recipe books (or so my wife tells me; I haven’t looked) say to leave the lid on the food processor closed for a full half hour after grating the horseradish root.

What do they know? There is nothing (in the legal pharmacopeia) to compare with the experience of lifting the lid of the food processor that first time.

At first, nothing. And then … wham! … you instantly become acutely aware of how extensive the network of sinus cavities in your head really is. Your eyes tear up, and you reflexively grip the counter-top for support.

And, sorry, unlike the rest of my blog, neither my chrain recipe, nor the labels are CC-Licenced.

Update: Ack! Boycott Melissa’s horseradish root. I’ve tried two different batches from two different supermarkets and, despite the initial fireworks, the result, both times, was dull and tasteless. Come to think of it, Melissa’s are purveyors of dull tasteless jicama, dull, tasteless tamarind, and other “speciality produce”. Avoid like … the plague.

The RIAA lawsuit against 4 college students barely registered on my radar. Ho hum, a bunch of college kids caught sharing an egregious number of MP3’s, I thought.

On closer examination, the “crime” of which these fellows stand accused is … the creation of a search engine. What each of them did was create software which indexed the files available as Windows (SMB) FileShares on their campus networks, and thereby provide a searchable web interface for tracking down that Linux ISO image or a term paper on the French Revolution.

In other words, they were doing what Google does, but for SMB FileShares on a LAN, rather than for for the whole WWW. Even without their search engines, a Windows XP user could still search the University LAN for SMB shared files, just a lot less efficiently.

Since the DMCA has a specific exemption for search engines, you gotta wonder what the RIAA hopes to achieve. (Reading this critique of the complaint against one of the students, Daniel Peng of Princeton, leaves little doubt in this layman’s minds as to how the case should be decided.)

The obvious answer is that they are engaged in pure intimidation. Go after some poor, scared-s***less students and win, lose or (most likely) settle, you strike fear in the hearts of their filesharing classmates. After all, if this is what happens to the author of a search engine, imagine what might happen to someone engaged in actual copyright-infringement.

Oh, and if you want to track down some Britney Spears MP3’s, why don’t you try here.

Back when I posted the lyrics to Xena; or, The Warrior Princess, one of our students came to me rather puzzled. He didn’t “get” it because, as it turned out, he’d never heard Gilbert & Sullivan’s Modern Major General nor Tom Lehrer’s The Elements (and here I thought all aspiring scientists were required to commit the latter to memory).

It’s with some measure of relief that I can point “B” to this Flash Animation in honour of Lehrer’s 75^th birthday (which was yesterday) [via More Like This].

Digby brings to our attention a Salon article on the ever-hilarious Jon Stewart’s Daily Show. Stewart skewers the prevailing media smugness with his usual deadpan humour.

You have been warned.

Blogging has been light as of late. One of the reasons is that I’ve been doing a major site-overhaul. “What?” you say, “Your site looks completely unchanged.” Well, exactly.

While trying to write an alternate stylesheet — for reasons that I won’t get into right now — I came to realize that my job was made much more difficult by the existing markup. The MovableType default templates are a morass of nested <div>s and <span>s. On top of that, I had added my own layers of cruft. Wading in, I realized what a tour de force Mena’s CSS stylesheets are.

What to do? Get rid of the unnecessary nesting, use <ul>s for lists of stuff, rather than

<div>
item 1<br />
item 2<br />
...
</div>

and use <h*> for headers, rather than yet more <div>s.

Same visual effect, but much simpler and easier-to-work-with code.

Been meaning to make some comments about this, but just hadn’t gotten around to it.

Lenny Susskind has taken the paper by Kachru et al as an “existence proof” for (meta)stable de Sitter vacua in string theory. I’ve written previously about some of the handwaving involved, and how one might try to improve upon it. But, even if you do believe it constitutes an existence proof, Lenny’s leap of faith — that the existence of one such solution means there must be gazillions of them — is nothing short of breathtaking. There are other things I could grumble about in his paper, but this is the heart of the matter.

Finding stable de Sitter solutions in supergravity is hard. Generically, one expects that supersymmetry-breaking will lead, not to a local de Sitter minimum, but to an instability. (In this class of theories, there’s always a “runaway” direction, where the scalar potential goes to zero at infinity; the problem is to produce a local minimum, with positive vacuum energy, at some finite value of the field.)

Mike Douglas has taken up the crusade, by embarking on a program to “count” supersymmetric “vacua” which, when supersymmetry-breaking is taken into account, would lead to de Sitter vacua. He then hopes to do statistics on the space of such vacua (analogous, I guess, to the Bayesian approach to the Anthropic Principle). But we know from many examples that supersymmetry-breaking can “lift” supersymmetric ground states. The non-supersymmetric theory may have fewer (even metastable) ground states than the supersymmetric one. Even granting all of Lenny’s assumptions, I don’t see the relevance of counting supersymmetric vacua.

Search for terrorist +website on yahoo.com and this blog turns up as #18 in the list of hits.

That is frightening. I shall have to be more circumspect in my comments about string theory.

In addition to being my desktop, Golem is my mailserver/webserver/… and my QuicktimeStreamingServer. This poses a problem because some people have their Quicktime client software configured to use HTTP/Port80 instead of RTSP/Port554. So, when they click “play” on one of the movies, the request is received by Apache instead of QTSS, and they get a 404. It doesn’t matter what garish warning I put on the web page, my Apache error logs show that some people can’t or won’t change their settings.

A few days ago, I realized that this was yet another job for mod_rewrite!

RewriteEngine On
RewriteBase /moviedir/
RewriteCond %{HTTP_USER_AGENT} QuickTime|QTS
RewriteRule ^(.*)$ http://golem.ph.utexas.edu:554/moviedir/$1 [L,R]

In other news, OpenSSH 3.6 is out.

And I decided to do the pure-CSS button thingie for my RSS feeds because the sidebar of my blog just didn’t have enough buttons.

P.S.: In case you couldn’t tell, it’s a spoof.