Category Archives: Physics

Things I Learned From Websurfing

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I learned several things today from websurfing.

From this comment by elzoro at Not Even Wrong, I learned that Richard Borcherds now has a weblog. The two posts so far are about physics.

From this comment by Peter Woit that the latest issue of the journal Topology is out, and the page that lists the editors is completely blank. (Remember that last year the entire board of Topology resigned to protest the journal’s high subscription fees, and started their own journal, the Journal of Topology.) I think that the publisher has to keep the journal going at all costs, since if the former editors of Topology succeed in completely supplanting their erstwhile journal, the commercial publishers will lose control of mathematical publishing pretty quickly.

From this anonymous comment at Computational Complexity, completely and cynically explains the rationale behind the Clay Millenium Prizes:

The point of the Clay prizes is not to provide motivation to solve the problems (anyone who solves one will have put in far more effort than a million dollars warrants), but rather to tie Clay’s name to the problems, so that nobody will ever discuss the Poincare conjecture without talking about Clay. To accomplish this, the prize has to be impressively large, on the scale of a lottery prize.

Time Is Short

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People of Earth,

Now that this has happened, time is short. I can only assume that the inhabitants of the planet around Gliese 581 have left us unmolested up to this point is that as long as we did not know of their existence we were no threat. Now that the word is out, I can only assume that their long-prepared invasion fleet is under way. Fortunately, we have 20.5 years until word reaches them, and another 20.5 before their planet-killing machines can acheive Earth orbit, so we must use the 41 years of peace left to us to prepare. I am not a crank.

Sincerely,

Walt

Electrical Networks and Random Walks

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People always post interesting links in the comments to Scott Aaronson’s weblog. For example, the other day Paul Beame posted two links that explain the connections between random walks on graphs and electrical networks. One is a complete book on the subject by Doyle and Snell. The other is an article by Chandra, Raghavan, Ruzzo, Smolensky, and Tiwari that further develops the theory.

2007 Abel Prize

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The 2007 Abel Prize has been announced. The winner is S. R. Srinivasa Varadhan for his work on large deviations in probability. Large deviations are asymptotic estimates of rare events. They are of practical importance, for example, in justifying the results of statistical mechanics. Cosma Shalizi’s notebook on large deviations provides an overview and many more links.

I find it interesting that the Abel Prize has taken a turn towards the applied in recent years. The first two awards, to Serre and to Atiyah and Singer, track the expectations of pure mathematicians. In the last three years, though, one prize has gone to Peter Lax, who works in applied PDEs, and now this year Varadhan. (The other winner is Lennart Carleson.)

Why Navier-Stokes is Hard

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Terence Tao has a thoughtful post that explains why proving existence results for Navier-Stokes equations is so hard.

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Revolution, Einstein-Style

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I ran across the oddest anecdote about Einstein. Einstein was teaching a class in Germany in 1918. When in the aftermath of World War I Kaiser Wilhelm abdicated, he put a sign on the classroom door that said “Class cancelled because of revolution.” (This link mentions the story.)

Srednicki on Quantum Field Theory

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Mark Srednicki has written a new textbook on quantum field theory. The final version is not available electronically, but a prepublication draft is.

It’s common for authors to take down the manuscript when the book is published, so it’s nice to see it when an author bucks the trend. Srednicki adopts a reasonable compromise in keeping the final-but-one version available on his site (he warns “This draft contains numerous errors (mostly minor) that are corrected in the published version”).

Mars, Chappelle-Style

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Sean at Cosmic Variance notes that NASA has discovered that everyone is apathetic about their new planned mission to the Moon and then Mars, and that they are in the market for a celebrity spokesperson to change that. They are throwing around obvious names, like David Duchovny and Patrick Stewart, when the answer is obvious. There is only one man for the job of selling the new Mars mission:

Dave Chappelle (warning: long, not safe for work, and you probably won’t think it’s funny).And if NASA is looking for a marketing slogan, they could do worse than what John Baez says here: “the scientific equivalent of putting a goldfish bowl on top of Mount Everest.” Think about it — we’ll never know what’ll happen to that goldfish unless we try. Dare to dream.