This coming week and the next Princeton will host both the big yearly string theory conference Strings 2014, and Prospects in Theoretical Physics 2014, a program designed to train young physicists in string theory.
Princeton is definitely the right place for this, since it now is very much a singular point in the world-wide theoretical physics research community. At the IAS the director is a string theorist, so is the past director (now faculty member). Of the other four senior HEP theorists, three are string theorists and one might be described as a fellow-traveller. Over at the university, of the nine faculty in HEP theory, all are string theorists except for one junior faculty member.
The Strings 20XX conferences provide a good place to see what the latest trends in string theory are, with the talks chosen to highlight what some of the most influential people in the field consider the most interesting work. I’ve written posts on the blog here about previous such conferences, which one can compare to this year’s to see how the field has evolved. Looking at the list of over 70 talks and their topics, some things that strike me (in many cases, much the same things as in other recent years):
- Talks actually about strings are a small minority (20%), something that has been true for quite a few years. The percentage may have grown from a minimum back in 2011 when some of the speakers were mentioning the small role strings were playing at a string theory conference.
- AdS/CFT and holography remain a dominant theme, as they have for many years. Possible applications of this to condensed matter physics are a continuing hot topic. The previous hot topic of this kind, applying AdS/CFT to heavy ion physics, now seems to be dead, something people would rather not talk about anymore since it never worked out as advertised.
- Amplitudes are the other big hot topic.
- Discussion of the LHC and hoped-for LHC results in the past was often a major topic at these conferences. Now that the LHC results are in and a huge disappointment (no SUSY or extra dimensions), it looks like there’s a chance the LHC will not be mentioned at all at this year’s conference, with “string phenomenology” in general the topic of only a very few talks.
- String phenomenology does have its own yearly conference (see here), but at least as far as the US participants go, the top US research institutions are not represented there, whereas they are heavily represented at the Princeton conference. Whatever “string phenomenology” is these days, it’s not popular at all among the Princeton crowd. It’s no longer being done at the most prestigious US institutions, and in Europe is concentrated in certain places (popular in England for some reason, not at all in France).
- While research into string theory unification schemes now seems to be very unpopular at Princeton, for some reason it’s a topic that the young must still be trained in. The PiTP program includes a series of lectures on string compactications, for which the Princeton people needed to bring in Martijn Wijnholt from Munich, one of the places still doing this kind of thing.
- To the extent there’s anything about connection to experiment, B-modes are the hot topic.
- There was a time when mathematicians were sometimes invited to Strings 20XX, but that’s over and done with. It seems most prominent string theorists no longer want to hear anything from mathematicians.
- Finally, zero about the multiverse or the landscape. Clearly some on the organizing committee still have strong opinions and are not going to tolerate that kind of nonsense.
Witten will just give a 15 min welcoming speech. In the past, David Gross has ended the conference with a “vision” speech. This year there will be five “vision talks”, and it may be interesting to see a wider range of opinions on where the field is heading.
Update: One more notable thing about this version of the yearly conference is that (as far as I can tell), it’s the first one in many years that has not included a promotional public talk about string theory. It may very well be that this was considered unnecessary in Princeton.
Update: Martin Wijnholt’s lectures to the students and postdocs in Princeton about string compactifications are available here. Lots of nice material on Calabi-Yaus and algebraic geometry, nothing at all about extracting the standard model from all this. One thing that has always surprised me is how little most string theorists know about the state of the art of getting particle physics out of the theory. This is less surprising now after seeing the kind of lectures they get on the subject.