- #36
MTd2
Gold Member
- 2,028
- 25
Witten's talking about 4D is no surprising. His most important contributions, since the beginning of his career, were about 3D and 4D theories. He got a fields for that.
Last edited:
MTd2 said:Did horava say something about his work with Cenke Xu, the one where he cites CDT?
http://arxiv.org/abs/1003.0009
There is a discussion about it here:
https://www.physicsforums.com/showthread.php?t=382873
marcus said: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.
marcus said: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'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.MTd2 said:... So, I didn't take interest in the Kerr-Fermi sea. But is there anything fundamental there?
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.yoda jedi said:string and loop are dead.