A random collection of links, on the whole not having anything to do with the holidays:
A Stanford Physics Student in Berkeley is now An American Physics Student in England, and reports from the DAMTP Christmas party, where people were supposed to be wearing “Sci-Fi” costumes, that one physicist came in a black t-shirt with the following printed on the front:
The Anthropic Landscape of String Theory
Leonard Susskind. hep-th/0302019
As far as I can tell, of string theory papers written during the last four years, this is the second most heavily cited (the first is the KKLT one that inspired it). How dare these English people act as if this is some sort of joke?
Raymond Streater’s Lost Causes web-site has always been a wonderful source of anecdotes and opinions. He has a new book coming out any day now from Springer entitled Lost Causes in and Beyond Physics which I’ve just ordered and am looking forward to reading. Streater’s web-site also includes a pretty hilarious commentary on Lubos Motl’s typically absurd review of one of Streater’s earlier books, the deservedly famous PCT, Spin and Statistics and All That, written with Arthur Wightman. I had never realized I was in such good company.
From Streater’s web-site I also found a link to an interesting talk by Guralnick on some of the history he was involved in of work on symmetry breaking in QFT during the sixties which ultimately led to the Glashow-Weinberg-Salam model and what is now known as the Higgs mechanism. The talk tells how leading physicists discouraged work on these ideas as “junk” that wouldn’t lead anywhere and would ensure that one couldn’t get a job. During these years the dominant opinion was that S-matrix theory was the route to future progress, with QFT a dead-end.
Back when I was a physics graduate student I remember every so often picking up a copy of the journal Foundations of Physics and flipping through it, trying to read some of the articles. From what I remember, at the time it struck me as a semi-crackpot phenomenon, mixing a few serious attempts at thinking about foundations with large heaps of nonsense. It seemed clear to me then that serious theorists worked on very different things, trying to understand gauge theories and the Standard Model. A friend of mine who was also a graduate student back in those days recently told me that now the current mainstream literature strikes him as much like that found in the old days in journals like Foundations. I don’t know what this means for physics, but Springer recently announced that Gerard ‘t Hooft (one of the main creators of gauge theory) is taking over as editor-in-chief of the journal. Maybe in times like ours in which there is no experimental guidance, work on foundations should get new emphasis (I think this is one of the points in Lee Smolin’s recent book).
If one wants an overview of recent developments in the interaction of math and physics, one could do a lot worse than read the proposal from various mathematicians and physicists in the Netherlands entitled The Fellowship of Geometry and Quantum Theory (via Klaas Landsman’s web-site).
John Baez’s student Derek Wise has a well-written paper about Cartan connections, and John provides some commentary in his latest This Week’s Finds in Mathematical Physics. I’ve always been fascinated by Cartan connections, since they provide a framework linking very general ideas about geometry with Lie groups. As John notes, they provide a joint generalization of the Riemannian and Kleinian points of view about geometry. They also seem to provide a natural mathematical framework for thinking about the relation between GR and gauge theory. Besides the references given by Wise, one should also note that Kobayshi-Nomizu, the standard reference text among mathematicians on geometry from the point of view of connections, is very much inspired by the idea of a Cartan connection. It seems likely to me that if we ever figure out how to properly understand geometrically how to unify gravity and the standard model, these ideas will be part of the story (although much else will also be required, including an understanding of the role of spinors, and of the geometry behind quantization).
Finally, for comic relief, Kris Krogh pointed me to a talk by Michael Berry from a few years ago, where he describes his experience back in 1985 at CalTech when he was working on quantum physics and zeta-functions, and met up with some of the local string theorists:
I met one of them, who asked what I was working on. When I told him, he fixed me with a pitying stare. “Yes, we have zeta functions throughout string theory. I expect the Riemann hypothesis will be proved in a few months, as a baby example of string theory.”
Update: Several people have pointed out that the Susskind t-shirt or the report about it contain a typo. The correct reference is hep-th/0302219
Update: There’s an interview with me posted on Scienceline, the web-site of the NYU Science, Health and Environmental Reporting Program, with the title Stringing Up String Theory.
Update: Yet another interview, this one with Lee Smolin at IEEE Spectrum on-line, called Thread-bare Theories.