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.
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….
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.