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Note:These pages make extensive use of the latest XHTML and CSS Standards. They ought to look great in any standards-compliant modern browser. Unfortunately, they will probably look horrible in older browsers, like Netscape 4.x and IE 4.x. Moreover, many posts use MathML, which is, currently only supported in Mozilla. My best suggestion (and you will thank me when surfing an ever-increasing number of sites on the web which have been crafted to use the new standards) is to upgrade to the latest version of your browser. If that's not possible, consider moving to the Standards-compliant and open-source Mozilla browser.

February 25, 2006


All I can say is … wow.

I’d hate to be one of the former Enron employees who’s [sic] SSN, credit card number, home address, phone number, etc. was readily available for anyone with a rudimentary regex parser

The public’s got a right to know 'n all, but couldn’t they have redacted this information?

Posted by distler at 10:16 PM | Permalink | Followups (1)

February 17, 2006

Innumeracy Watch

Soon after getting my PhD, I went out to buy my first car. The manufacturer was offering very advantageous 1.9% financing, a deal to which I naturally agreed. When I went in to sign the papers, the salesman looked in his little book, and announced, “Your monthly payment will be …,” stating a figure noticeably higher than I had figured. I reached into my breastpocket and pulled out a piece of paper. “According to my calculations, that should be … Why the higher figure, Chet?” (Slimeball car salesmen always seem to have names like “Chet.”) “Oh, that’s the … <mumble, mumble> … insurance.” “I don’t need insurance. I’ll pay the …” There was some hemming and hawing, but the loan papers were redrawn, and I eventually signed.

Which brings us to the sad case of Richard Cohen [via P.Z. Myers], who insists that being ignorant of basic algebra, far from being a handicap, is positively a good thing,

I confess to be one of those people who hate math. I can do my basic arithmetic all right (although not percentages) but I flunked algebra (once), barely passed it the second time…

Here’s the thing, Gabriela: You will never need to know algebra. I have never once used it and never once even rued that I could not use it. You will never need to know – never mind want to know – how many boys it will take to mow a lawn if one of them quits halfway and two more show up later – or something like that. Most of math can now be done by a computer or a calculator. On the other hand, no computer can write a column or even a thank-you note – or reason even a little bit. If, say, the school asked you for another year of English or, God forbid, history, so that you actually had to know something about your world, I would be on its side. But algebra? Please.

Here’s the thing, Mr. Cohen. I don’t care whether you enjoy going through life being cheated by every slimeball named “Chet” who has the good fortune to cross your path. If you’re unable to figure out that the monthly payment, mm, on a loan with Principal, PP, consisting of nn monthly payments at an annual interest rate, pp, is given by the formula1

m=P(1+p1200) n k=0 n1(1+p1200) k m = P \frac{\left(1+\frac{p}{1200}\right)^n}{\displaystyle{\sum_{k=0}^{n-1}} \left(1+\frac{p}{1200}\right)^k}

well, that’s too bad for you. And I’m sure the Chet’s of this world will be only too glad to “help” you figure out whether it’s time to refinance your mortgage or how best to save for retirement. It’s only money after all…

No, it’s when Mr. Cohen turns to commenting on matters of public policy that his innumeracy becomes a threat to the public discourse. And, most of all, it’s when he offers girls like “Gabriella” the ‘wisdom’ that Math is hard and she needn’t worry her pretty little head about it, that I really get steamed.

I have a 10 year old daughter and I’ll be damned if she succumbs to the societal cues, coming from all side, to the effect that girls are just not cut out to understand math. Wallow in your own innumeracy, if you wish, Mr. Cohen. But keep your mitts off my daughter, thank you very much.


Here’s the news article that inspired Mr. Cohen’s column. Apparently, a lot of schools are not equipped to teach algebra to their students and the students are not prepared to learn it. Ergo, it must not really be important…

Update (2/18/2006):

A reader (I have the best readers) wrote in to point out that I should have done a bit more … algebra. Using the identity k=0 n1x k=x n1x1 \sum_{k=0}^{n-1} x^k = \frac{x^n-1}{x-1} one can rewrite (1) in the more calculator-friendly form:
m=Pp1200(1+p1200) n(1+p1200) n1 m = P \frac{\frac{p}{1200} \left(1+\frac{p}{1200}\right)^n}{\left(1+\frac{p}{1200}\right)^n -1}

which, now that I think about it, was probably the form that I actually used.

You Passed 8th Grade Math
Congratulations, you passed!
Congratulations, you got 10/10 correct!

Update (2/25/2006):

You can try your own hand at some of the horrible stuff that Richard Cohen thinks “Gabriela” shouldn’t worry her pretty little head about. I’m not actually that fond of the test. Too many nearly identical questions involving a linear equation in one variable. And at least one of the questions (#6) is of the rote-memorization (“The Gobi desert is in Asia; the Sahara is in Africa.”) variety that Cohen is so fond of.

1 Yes, I think I used a computer to evaluate this expression. Computers are great for tasks like that. They are, like any mechanical aid, an extension of, not a replacement for our ability to think quantitatively.

Posted by distler at 5:06 PM | Permalink | Followups (26)

February 16, 2006

Camino 1.0

Camino 1.0 is out. And it finally joins the rest of the Mozilla family in supporting MathML.

It’s quite fast, and has a bunch of slick features1. All in all, it’s a very attractive Cocoa-based browser, a worthy alternative to Safari.

For those who are keeping track, my rule for selecting the MIME-type with which to these pages is

RewriteRule ^$ index.shtml
RewriteCond %{HTTP_USER_AGENT} Gecko|W3C.*Validator|MathPlayer
RewriteRule \.html$|\.shtml$   - [T=application/xhtml+xml]
RewriteCond %{HTTP_USER_AGENT} Chimera|Camino/0|KHTML
RewriteRule \.html$|\.shtml$   - [T=text/html]

which says that the W3C Validator, Gecko-based browsers (including Camino 1.0 and above), and IE6 (and above) with the MathPlayer plugin installed, receive application/xhtml+xml. Everyone else receives text/html. Technically, late-model versions of Opera and Safari could handle application/xhtml+xml. But there’s no point, so I don’t bother.

Update (2/19/2006):

At Zack Ajmal’s urging, I’ve shifted to sending application/xhtml+xml to all UAs with that in their Accept header. My rewrite rule is
RewriteRule ^$ index.shtml
RewriteCond %{HTTP_ACCEPT} application\/xhtml\+xml [OR]
RewriteCond %{HTTP_USER_AGENT} W3C.*Validator|MathPlayer
RewriteRule \.html$|\.shtml$   - [T=application/xhtml+xml]

This change currently only benefits users of Opera 9. But, hopefully, Safari will get fixed someday, too. The bottom line is that, if you don’t see 平和と静けさ displayed in an attractive shade of green, then your browser is — in some fashion or other — defective.

1 That’s the good news. The not-so-good news is that, like Firefox 1.5, it now contains the still-rather-crappy builtin SVG renderer. This make a mess of the SVG figures I include in various blog posts hereabouts. Notably, it

  1. Has no support for the SVG Font Module.
  2. Doesn’t support ViewPort Size negotiation.

Opera’s builtin SVG renderer, and the one in the Safari Nightly builds, have the same problems.

There’s a workaround for the second problem. Adobe Illustrator outputs SVG files which say something like

<svg  width="345" height="249" viewBox="0 0 345 249">

If one changes this to

<svg  width="100%" height="100%" viewBox="0 0 345 249">

they will scale OK in Firefox/Camino and Opera. I’ve done that with the figures here at Musings, but it’s really a bad idea. Instead, the Mozilla, Opera and Safari people should fix their SVG renderers. And, while they’re at it, they can implement the Font Module…

In the meantime, if you have the Adobe SVG plugin installed, you can disable the builtin SVG renderer by going to about:config and setting svg.enabled to false.

Posted by distler at 11:41 AM | Permalink | Followups (12)

February 15, 2006


I’ve written before about Berkovits’s Pure Spinor formalism for the superstring and its relation to curved β\beta-γ\gamma systems. One of the issues one has to deal with is that the algebraic variety one is trying to study (the space of pure spinors) is singular. For d=10d=10 Euclidean pure spinors, it’s a complex cone over Q˜=SO(10)/SU(5)\tilde Q= SO(10)/SU(5). As I discussed, Nekrasov proposed to deal with this particular issue by omitting the tip of the cone.

Grassi and Policastro propose an alternate approach which, they claim, allows one to deal directly with the singular affine algebraic variety. Consider a (set of nn) spin-1 β\beta-γ\gamma system(s) with action S βγ=12πβ i¯γ i S_{\beta\gamma} = \frac{1}{2\pi} \int \beta_i \overline{\partial} \gamma^i One would like to impose some polynomial constraints Φ a(γ)=0 \Phi^a(\gamma)=0 Grassi and Policastro propose to implement this via the Koszul-Tate Theorem. Introduce a set of spin-1 anticommuting ghosts S bc=12πb a¯c a S_{b c}= \frac{1}{2\pi} \int b_a \overline{\partial}c^a and the Koszul-Tate differential δ˜=12πib aΦ a(γ) \tilde\delta = \frac{1}{2\pi i} \oint b_a \Phi^a(\gamma) If there are relations among the constraints, f a(γ)Φ a(γ)=0 f_a(\gamma)\Phi^a(\gamma)=0 then one may need to introduce ghosts-for-ghosts, and the procedure becomes a bit messy. This certainly happens in the pure spinor case, where the Fierz Identities introduce relations of this form.

We happen to be interested in the particular case where the Φ a\Phi^a are homogeneous quadratic polynomials, so we can assign a grading J g(z)=J βγ(z)+2J bc(z) J^g(z)= J^{\beta\gamma}(z) + 2 J^{b c}(z) such that δ˜\tilde\delta has grading equal to zero.

The claim is, now, that computing the cohomology of δ˜\tilde\delta, restricted to the subspace with non-negative values of the grading gives the correct spectrum of the constrained theory. Grassi and Policastro have checked this in a few simple examples.

In the general case, I’m not quite sure what “correct” means. In their examples, one can resolve the cone to a smooth variety, and the spectrum doesn’t change. That’s the sort of result one would expect from an application of Koszul-Tate. But, as we’ve already seen, resolving the conical singularity in the case of the cone on Q˜\tilde Q give the wrong answer for the pure spinors. The resulting variety has nonzero p 1p_1, and so the curved β\beta-γ\gamma system suffers from an anomaly.

Posted by distler at 11:50 PM | Permalink | Followups (4)

February 6, 2006


As you’ve all probably heard, a furor has erupted about yet another wingnut political Appointee, a certain George Deutsch, a 24-year old Press Officer at NASA, who took up the vital task of putting the secularist astrophysicists in their place

In October 2005, Mr. Deutsch sent an e-mail message to Flint Wild, a NASA contractor working on a set of Web presentations about Einstein for middle-school students. The message said the word “theory” needed to be added after every mention of the Big Bang.

The Big Bang is “not proven fact; it is opinion,” Mr. Deutsch wrote, adding, “It is not NASA’s place, nor should it be to make a declaration such as this about the existence of the universe that discounts intelligent design by a creator.”

It continued: “This is more than a science issue, it is a religious issue. And I would hate to think that young people would only be getting one-half of this debate from NASA. That would mean we had failed to properly educate the very people who rely on us for factual information the most.”
(emphasis added)

I have only a couple of things to add to the fine discussions going on elsewhere.

  1. Yes, Big Bang Cosmology is a Theory. A very well-established Theory. Just like Quantum Electrodynamics is a Theory, Plate Tectonics is a Theory and (yes) Evolution is a Theory.

    I don’t care if you don’t believe in Quantum Electrodynamics. Really. And it’s fine with me if you feel it more theologically-congenial to believe that færies blow the continents around, like soap bubbles in the bath.

    Just don’t presume to tell me that these are the subjects of legitimate controversy and that we, as scientists, need to tread lightly. And don’t expect me to listen respectfully, while you expound on the Færie Theory of Continental Drift.

  2. Stop calling it “The Big Bang Theory.” Nobody calls it that. Makes you sound like a rube.

Update (2/7/2006): Deutch Resigns from NASA

Not, apparently, because he’s a political hack and a scientific ignoramus. But because he lied on his resumé.

As NASA’s top Climate Scientist says,

He’s only a bit player,” Dr. Hansen said of Mr. Deutsch. “He’s amusing because he goes to these extremes, but the problem is much broader and much deeper and it goes across agencies. That’s what I’m really concerned about.”

“On climate, the public has been misinformed and not informed,” he said. “The foundation of a democracy is an informed public, which obviously means an honestly informed public. That’s the big issue here.”

But, in this instance, I guess we’ll take what we can get.

Posted by distler at 8:53 AM | Permalink | Followups (10)

February 5, 2006

The People Garden

The People Garden. A family musical at the Zachary Scott Theater

I’m not much for posting “Today I Had a Cheese Sandwich”-type blog entries. I can’t see why anyone would be interested in the daily details of my life, when their own is surely much more interesting.

But, as I’ve alluded to in several posts, I’ve been spending a lot of time, recently, hanging around the Zachary Scott Theater, here in Austin. Here’s why. My daughter is playing the role of “Adam” in the Zach’s production of The People Garden. It’s a heartwarming little musical about the meaning of life, as revealed in a kindergarten class.

The show is in its final, hectic, week of rehearsals. It opens this Saturday, and runs through March 15. If you’re anywhere near Austin, check it out. I may be a trifle biased, but I’m pretty sure you won’t be disappointed.

Posted by distler at 10:33 AM | Permalink | Followups (4)

February 4, 2006

Behind the Horizon

I never did write about Fidkowski et al’s work on attempting to probe the blackhole singularity in AdS 5\text{AdS}_5, by studying correlation functions of the boundary theory. Hong Liu visited us this week, and gave a nice talk about his work with Festuccia, which gives me an excuse to catch up.

Posted by distler at 3:26 PM | Permalink | Followups (1)