Not Even Wrong

As far as academics are concerned, summer has started, which means that there are lots and lots of conferences going on. The past couple weeks we’ve had two here in the Columbia math department, one in algebraic geometry, and another covering various related topics in hyperbolic geometry and knot theory.

Next week 450 or so physicists will gather for the big annual string theory conference, and a couple weeks ago there were more than 400 participants at the big annual SUSY conference, SUSY 2009. For more on this, see reports from Jester and Sabine. Jester’s take on the conference included:

Over 400 participants, not counting squatters. 42 plenary speakers, most of whom witnessed the glorious days when supersymmetry was conceived. Seven parallel parallel sessions to cover every aspect of supersymmetry that has not yet been covered thoroughly enough. Royal coffee break menu fully adequate to the royal conference fee. And so on and on since 16 years and into the future.

Meanwhile, there is no single hint from experiment that supersymmetry is realized in nature… but that should not upset anyone. As my fellow blogger skillfully put it, supersymmetry is the “shining beacon”, the “raison d’etre” and for this reason “the conundrum is how it will be discovered, not if”. That’s why every year we come together to enjoy old familiar faces and old familiar talks. The point is, while waiting for the inevitable, to maintain that kind of spirit that David Lodge praised in his books.

At Santa Cruz this week, there was a conference in honor of the 60th birthdays of Tom Banks and Willy Fischler, blogging from David Berenstein.

At Penn there’s a summer school on Geometry of Quantum Fields and Strings, blogging at Rigorous Trivialities.

On the multiverse front, Thibault Damour has a survey article about constancy of physical constants, where he makes the reasonable argument that checking such constancy is one of our few ways of getting insight into the origin of these parameters of physical theory. Sometimes you see the claim made that string theory predicts time-dependence of constants (since they are moduli parameters), other times the claim is made that string theory does make one prediction, that such constants won’t change (due to energetics of the landscape). Damour summarizes this as

However, there is no firm prediction for the observable level of EP violation. Actually, the current majority view about the “moduli stabilization” issue in String Theory is to assume that, in each string vacuum, the coupling constants are fixed by an energy-minimizing mechanism which is generically expected to forbid any long-range violation of the EP. This, however, makes EP tests quite important: indeed, they represent crucial tests of a widespread key assumption of string-theory model building. This exemplifies how EP tests are intimately connected with some of the basic aspects of modern attempts at unifying gravity with particle physics.
Some phenomenological models (inspired by string-theory structures, or attempting to understand the cosmological-constant issue) give examples where the observable EP violations would (without fine-tuning parameters) be just below the currently tested level.

The “string universality” principle discussed here recently is related to Leibniz’s “Principle of Plenitude”:

all logically possible “things” (be they objects, beings or, even, worlds) have a tendency to (and therefore must, if one does not want contingency – be it God’s whim – to reign) exist.

So, experimental measurements are important not because they can tell us whether string theory is right or wrong, but because they can tell us which kind of string theory is right….

The latest Seminaire Bourbaki was last week, here’s a summary of the talks. Edward Frenkel has posted his survey of Gauge theory and Langlands duality on the arXiv.

Earlier this week I learned from my colleagues one obscure piece of mathematical culture that I had been unaware of. Physicists have the famous story of how Alpher and Gamow brought in Bethe as co-author to improve the author list, but it turns out that mathematicians have a somewhat different story of this kind. At lunch one eminent algebraic geometer started snickering when someone (using standard terminology) brought up the well-known ring associated to an algebraic variety due to David Cox. At this, it was pointed out that Cox was co-author of a famous paper with Steven Zucker, and the story goes that this came about because Cox had decided once he heard of Zucker that a Cox-Zucker paper just was asking to be written. A supposedly authoritative source on the internet claims:

Cox and Zucker were admitted as grad students to Princeton in precisely the hope that they would someday collaborate. This kind of forethought is why Princeton is Princeton.

For a related mention of this, see the Journal of Improbable Research.

This past weekend the city of Villeneuve-sur-Yonne organized a science festival entitled La tête dans les étoiles; les pieds sur terre! It featured Lubos Motl speaking on “Physics at the Planck Scale”, and the Bogdanoff brothers on “The Beginning of Time”.

String theorist Oswaldo Zapata continues (see here for an earlier posting about this) his remarkable series of essays about string theory and how it came to dominate research in theoretical high energy physics. The latest one, entitled The Music of the Superstrings is about the metaphorical use of classical music to promote superstring theory, and it concludes:

Metaphors are powerful rhetorical tools. But, at the same time, they are much more than that. Indeed, when used astutely, that is, when anchored in deep shared meanings and aspirations, they can create an enthusiastic army of supporters to the discourse displayed. This has been one of the strongest weapons of string theorists in the battle for the control of future research in high energy theoretical physics.

Zapata examines how and why string theorists have chosen to advertise string theory to the public by claiming a deep connection to music, especially to classical music. He recalls the many ways this analogy has been promoted by many different string theorists, from Brian Greene, who has made it a prominent part of his popular explanations of the theory, to Edward Witten, who told an interviewer in 1988:

In the case of a violin string, the different harmonics correspond to different sounds. In the case of superstring, the different harmonics correspond to different elementary particles.

I’ve always found this kind of thing grating, for a reason that Zapata doesn’t address. Statements like Witten’s give people the impression that the known fundamental particles of nature somehow correspond to the harmonics produced by vibration of a string. This is rather misleading, since all known particles correspond to the lowest energy state of the string. The quantum states corresponding to “harmonics” of a string are all supposed to be at unobservably high energy. The way the theory is sold to the public, via the musical metaphor that electrons and muons are different “harmonics” of a string vibrating at different frequencies makes it seem that such particles can be matched to the characteristic behavior of the harmonics of a string-like mechanical system, which is simply not true.

Zapata also now has a Reactions page, where he has posted links to commentary about his essays, as well as some comments from Bert Schroer in a recent preprint.

Steve Miller pointed me to a fascinating interview with Jim Simons and C. N. Yang, available on YouTube here.

Simons tells the story of how he got kicked out of his job at the IDA in 1968 over his opposition to the Vietnam War, and ended up at Stony Brook as chair of the math department there. He and Yang collaborated on raising money to support anti-war efforts.

They describe how Yang went to Simons to try and find out about fiber bundles and what they might have to do with gauge theory. Simons started by referring Yang to Steenrod’s The Topology of Fibre Bundles, which Yang couldn’t make any sense of (Simons admits he never made it all the way through the book himself). This did in the end lead Simons and Yang to some real understanding of how vector potentials in gauge theory and connections on bundles were the same thing, with monopoles examples of topologically non-trivial bundles. Simons lectured at Stony Brook in 1975 on this, and a paper later that year by Wu and Yang included what became known as the “Wu-Yang dictionary” relating terminology in gauge theory and geometry. Singer learned about this soon thereafter when he visited Stony Brook, and went on to spread the news to Oxford, MIT and elsewhere.

Simons also describes what is going on with plans for the new Simons Center for Geometry and Physics, including some of the thinking that led him to decide to support this. The official ground-breaking ceremony for the new building there was held last week, you can follow construction progress here.

Strings 2009 is about three weeks away, and it will bring 450 or so string theorists to Rome. The topics of the talks at the Strings 200x conferences give a good idea of what the hot topics in the field are, and this year’s talk titles are now available. What’s big this year are scattering amplitudes, as well as the usual AdS5/CFT4 topics, supplemented by the more recently popular AdS4/CFT3. As far as phenomenology goes, the hot topic is definitely local F-theory models, with three separate talks on the subject.

One topic that is not hot is anything mathematical, with no research talks by mathematicians or Witten, and little about mathematically significant topics such as mirror symmetry. What also seems to no longer be hot is either string cosmology or the landscape. No cosmology, multiverse or Boltzmann Brains are to be found among the research talks, although Brian Greene will give a public lecture about the issue of possible multiple universes.