Strings 2010: Schedule of Talks

[MTd2]

I was just kidding!

 

[marcus]

Oh, just kidding. I see
Well the answer is that what Witten does or doesn't do is not so important now, but he hasn't shown much real interest in string since around 2006.

In 2007 he gave a talk at Strings 2007 that wasn't about string---it was 3D quantum grav.
He didn't attend Strings 2008.
He gave no paper at Strings 2009, but delivered an evening lecture to the public, that was not about string. And also in 2009 gave a major perspective talk at CERN about the future of physics "away from the high energy frontier" which barely mentioned string.
Practically speaking he has made it clear to the string community that he is a free agent and that they can't exactly count on him. On the other hand there continue to be attractive projects in string mathematics...

 

[marcus]

MTd2 I think your "just kidding" reference to Witten might distract readers. I didn't think his talk was all that interesting or important. We should try to focus on what we can learn from the conference. Weinberg's talk got a lively response. It was probably the most interesting talk that day, maybe the whole week!

I'll copy my post about it, to refresh the memory.

I just listened to portions of talks by Weinberg, Horava, and Lance Dixon.
Weinberg's was the most interesting talk of the conference, for me. And the most nonstringy.
He highlighted recent work by Benedetti Machado Saueressig, and also by Niedermaier. He got more and livelier questions after the talk than any speaker I heard all week, with the most exciting 5 minutes of the conference being a rapid-fire Q&A between Weinberg and Edward Witten.

Witten seemed seriously interested by Weinberg's talk, and jumped right in with questions. The two seemed to immediately understand each other so no time was wasted on hem and haw. Good to hear that level of engagement.

Weinberg pointed out unresolved issues with the Asymptotic Safe gravity approach. We should not take for granted. However: "there's no question Newton's constant runs." And
"effective field theory may be all there is up to arbitrarily high energy."

He was especially interested in applying A.S. to cosmology. It isn't clear yet that the conjectured explanation of inflation will work. If we follow Benedetti Machado Saueressig analysis, there would not be enough "e-foldings" of inflation produced by the running of the constants. Some inflationary episode but ending too soon. Needs work, but judged worth investigating.
=============
Horava said explicitly that his approach is indeed a "plan B to string theory". In other words a lifeboat in case of trouble with the ship of string. But he emphasized the common elements, how techniques could be carried over, so he presented it as an attractive transition path for emigré string theorists. A new but not altogether unfamiliar line of research that some could shift over into.

And then the topic of HOLOGRAPHIC SUPERCONDUCTIVITY has definitely been hot. A lot of people have started working in that area, and gave papers on it.

I think we are seeing a variety of "exit strategies" being presented. Good things for string theorists to work on that are more in the direction of 4D and/or real world. Yet have some carry-over in terms of math techniques---some familiar aspects.

I'm hoping to see more of these "bridges" that will allow string theorists to put their skills to use and steer their careers in more productive directions in the coming years.

Horava's move is kind of ideal in this respect, and he has a lot of followers. Another hopeful sign, IMHO, what Andy Strominger is doing. He is studying real 4D black holes, at least in part, and finding out new stuff. He could go to GR19 and present his Fermi sea paper to the regular GR research community, if he chose to, I think. He is not just a string theorist any more. It would be good if more of them developed that kind of breadth, don't you think?

 

[MTd2]

He is not just a string theorist any more. It would be good if more of them developed that kind of breadth, don't you think?

I think it is great when people start thinking like t'Hooft! Never get attached to any concept as fundamental, like quantum mechanics! Thinking outside the box, instead of clinging to a concept, such as string theory, when we still do not have the means to test it.

It would be a huge win for all theoretical physics if Witten discussed any physics that didn't have any supersymmetry in it.

I like the fundamental of things, like the manufacture of transistors of computers and concepts of nature. So, I didn't take interest in the Kerr-Fermi sea. But is there anything fundamental there?

 

[marcus]

... So, I didn't take interest in the Kerr-Fermi sea. But is there anything fundamental there?

i'm not necessarily the person to ask, and I hope some other(s) may respond. But as far as I know NOT. But I think it has empirical potential. There could be observable consequences. We have to respect anybody who can derive some new observable phenomena from quantum gravity models, or even from classical black hole models. It is such a deep and difficult problem, any kind of authentic phenomenology deserves consideration.

So I think it is maybe not fundamental particle physics, but at this point in history it might turn out to be as important as a modest particle theory innovation might be.

Why wouldn't Strominger get in touch with Bee Hossenfelder, who is running a QG phenom conference this summer? Are these people all so fragmented they don't talk to each other?
Why wouldn't Strominger contribute a presentation to GR19 in Mexico City this July?
I want to see some getting together and some crossing of lines.

 

[MTd2]

The slides of many of the talks are already available:

http://mitchell.physics.tamu.edu/Conference/string2010/TitleofTalks.html

 

[MTd2]

Horava and Weinberg's talk are already available:

http://mitchell.physics.tamu.edu/Conference/string2010/documents/slides/Weinberg.tamu10sw.pdf

http://mitchell.physics.tamu.edu/Conference/string2010/documents/slides/Horava.tamuP4.pdf

Ha! Horava cited Benedetti, Loll, Jacobson and Verlinde!

BTW, his talk have totally new content!

 

[yoda jedi]

string and loop are dead.

 

[petergreat]

string and loop are dead.

My uninformed guess is that string theory won't eventually die unless the LHC 1)Finds no supersymmetry 2) Finds no extra dimension 3) More importantly, finds something completely new which has nothing to do with string theory (4th generation?), so people get distracted away from strings and jump on some new bandwagon.

Another possibility is that the Planck Satellite, soon to release data, discovers some crazily non-Gaussian CMB, so people flow from particle theory to cosmology. Although some aspects of cosmology are also depressing. For example they have been chasing the idea of cosmic strings since the time people didn't know about string theory, but such objects still have no experimental proof. Inflation remains a field which promotes wild guesses about its cause, but no one can convince others.

 

[yoda jedi]

astrophysical high energy photons.

 

[MTd2]

I guess Marcus will really enjoy this talk:

http://mitchell.physics.tamu.edu/Conference/string2010/documents/slides/Dixon.LDNeq8Strings2010.ppt

Dixon says that N=8 SUGRA in 4 dimensions might be in the swampland after all, that is, it is no kind of low energy limit of any type of compactification of any string theory. During the talk you can see that at low loops this theory coincides in many terms but at highest orders, it seems that there is a disagreement between what is obtained from string theory aproximations and direct computations using maximum cut diagrams.

Dixon talks about the possibility that the UV completion might be a punctual theory, not string theory.