One can keep track of what is going on in theoretical physics now by taking a look at conference websites. Often after the conference they put up speaker’s transparencies or even audio or video of the talk. Some very recent examples:
Strings and Cosmology
a conference last week at Texas A and M, and
Spring School on Superstring Theory and Related Topics
at the ICTP in Trieste. Among the Trieste lectures, Marcos Marino’s notes give a nice discussion of some things you can do with topological strings. Brandenberger’s notes on “Challenges in String Cosmology” include the peculiar statement that “String cosmology does not exist because non-perturbative string theory is not yet known”. That was my impression too, but this doesn’t really explain why he is lecturing on a subject that doesn’t exist or why people devote many conferences to it.
Among the new papers appearing at the arXiv is Witten’s latest:
Parity Invariance for Strings in Twistor Space
I’m still kind of not seeing why Witten and others are so interested in this. Using strings as a dual to QCD to understand its strong coupling behavior is obviously interesting, but why is reformulating something you understand well (perturbative Yang-Mills) in terms of strings in a super-version of twistor space so interesting? The interesting thing about twistors always seemed to me that they were naturally parity asymmetric, one chirality of spinors is tautologically defined. Witten’s latest paper seems to just be showing how to get rid of this natural chiral asymmetry in this case.
Another new paper is:
The Emergence of Anticommuting Coordinates and the Dirac-Ramond-Kostant operators
by Lars Brink. The Kostant version of the Dirac operator is pretty amazing and too little known, both among mathematicians and physicists. I’m not so sure what Brink is trying to do with it leads anywhere, but there are other applications of it I’ll try and write about some day.