Sorry to have come late to this interesting thread – I hope John, at least, is still reading.
I think that math blogs will flourish to the extent that barriers to entry, both real and perceived, get lower. To some extent that’s simply a function of it being perceived as a “normal” thing for a mathematician to do. More specific thoughts on this:
1. My own blog is quite a bit different from the “usual” math blog, if there’s yet such a thing. Namely: it’s really a personal blog in which about 30% of the posts are in some sense about math, and the rest is about books I’m reading, records I’m listening to, the baseball team I follow – you know, the stuff that 95% of all blogs are about.
On the one hand, I think this makes my blog less “serious” – on the other hand, WordPress makes it very easy for anyone who doesn’t care about my favorite baseball team to read only the posts tagged “math.”
I think many people who don’t feel up to the task of producing the amount of high-quality mathematical exposition per week that Terry does might feel more capable of, thus more inclined towards, doing what I do.
2. Writing good exposition suitable for newcomers to a technical field is very, very hard, and simply can’t be done in a short space. If I asked this of myself all the time I wouldn’t blog. Instead, I use blog posts about new papers I’ve noticed or talks I’ve seen as ways to record for myself what I take to be the main points, or what I want to remember. Sometimes these posts are legible to people outside a specific research area, sometimes not. I think this is OK and we should make sure potential bloggers know this is OK.
3. I rarely use LaTeX in my blog, just as I rarely use LaTeX in e-mails about math. Somehow this works for me as a psychological aid, reminding me that what I’m writing is supposed to be conversational and not something I’d write in a paper.
4. Someone asked above about the actual size of the readership of math blogs. Mine is very small compared to Tim’s or Terry’s or nCat – about 130 subscribers on Google Reader, between 200 and 300 hits most days, somewhere between 0 and 5 comments on most posts. It’s worth telling people that your blog doesn’t have to be mega-popular to be worthwhile; I’ve found my blog to be fantastically satisfying, and I don’t begrudge any of the time spent writing it.
5. Now I’ll throw in one piece of barrier-raising: I think the concern of “sounding stupid” is one that senior folks like me, and many other math bloggers, can safely ignore. But younger mathematicians are not at all wrong to worry about it. I’ve certainly had the experience of hearing that senior mathematician X has formed a bad opinion of young mathematician Y because of wrong or careless postings on Y’s blog.
On the other hand, any blog likely to generate this kind of negative reaction from professor X_1 no doubt increases Y’s name recognition enough to helpful at hiring time, when blog-reading hiring commmittee members X_2, X_3, and X_4 have some prior knowledge of Y’s interests and work.
Re: What Do Mathematicians Need to Know About Blogging?
Cranks. With the ease of the internet, they’re around a lot more than just in unsolicited manuscripts in your mailbox.
No matter what you say, no matter how innocuous, there’s going to be someone who will take dire offense to it, and will not hesitate to let you know. What you need to know as a blogger is that just because one attacks you it doesn’t mean there aren’t a hundred people silently agreeing. Politely, firmly turn the crank aside and ignore him (or ban him if you know how) if he keeps coming back.