Successors to string scuffle (physical assets/liabilities?)

[heinz]

Have any new approaches that you think are important come to light in the past 3 months?

I am discussing with Schiller on his "strand model" on another thread. There are many open issues, in my opinion; but he obviously sees the strand model as a candidate for a theory of everything. Despite the many open issues, I would agree that it is a candidate. This does not mean that I think that it is correct; in my opinion, it is too early to say that, or to say the opposite.

 

[marcus]

In retrospect, a lot of what we were discussing in this thread is actually part of the
no-frills unification trend in fundamental physics!

One of the things we already discussed a lot in this thread is Nicolai's unification gambit, which is kind of the archetypical no-frills proposal. He expounded it in that Wroclaw Planck Scale talk that in the other thread I said would be the "manifesto" of the movement if it is a movement.

And also remember that nearly the top thing in the poll, in this thread, turned out to be ASYMPTOTIC SAFE GRAVITY! And that fact about gravity---its apparent UV fixed point---has provided kind of a backbone for the no-frills approach to get off the ground.
Asymsafe gravity means a number of different things---takes part in several different approaches. I realize now, more that when I set up the poll, that it is not just one thing.

BTW Garrett, who is in touch with the pro theory scene, responded to the poll and chose Asymptotic Safety and the category with most interest/potential. Things like that can serve as straws in the wind for us.

 

[MTd2]

I should had voted for Asymptotic Safety. It is just simple and beautiful. After knowing that, I have no confidence at all at anything supersymmetric beyond the level of providing qualitative toy models.

 

[apeiron]

Horava QG
A video lecture by Horava himself. Fixed camera though. We may get something better after the November conference.
http://online.itp.ucsb.edu/online/adscmt_m09/horava/rm/flash.html
Video: "Quantum Gravity with Anisotropic Scaling"

5 for Loop (Christine, MTd2, tom.stoer, SW VandeCarr, marcus)
2 for AsymSafe (william donnelly, marcus)
2 for SUGRA (arivero, tom.stoer)
2 for CDT (marcus, BigF)
1 for Regge (marcus)
1 for Xiao-Gang Wen ('Sabah)

How come no votes for Horava QG? Matt Visser describes it as this year's feeding frenzy, with two to three papers a day submitted in May and June.

He says it looks like it could underpin either a string or loop interpretation so has the promise of being more basic. It is background dependent of course. But despite being a GR guy, he does not think this is a deal-breaker in practice.

Is there a reason why it is not registering on the "hotness" meter here?

 

[marcus]

Interesting question Apeiron. Something that helped me personally decide was watching Ted Jacobson sum up the Perimeter conference on Horava gravity.
http://pirsa.org/09110066/

Remarkable performance. Jacobson decided to attend the conference as a good way to learn about HorGrav, he had not done research in it, and IMHO probably will not. Naturally he was not intending to present a paper! However he's an old QG hand and highly respected, so (seeing that he was there) the Perimeter organizers asked him to give the summary talk at the end.
Jacobson showed deep insight and a light touch. In my view he demolished HorGrav without showing the slightest desire to do so---in a gentle, casual, offhand way.

That was mid-November 2009. Do you have anything more recent than that from Matt Visser? The Horava fad trajectory has been fast-moving. I'd be curious to know what a distinterested commenter might have to say in the present timeframe.
It's certainly of academic interest, in the sense of being new visible and accessible---if someone wants to write a paper investigating some hypothetical case, some aspect, they can get in quick, write the paper, and get out without too much trouble.

So yeah, Matt Visser's description of a mid-2009 "feeding frenzy" is quite apt. HorGrav was a perfect setup for a feeding frenzy---this regardless of it's eventual prospects.

 

[apeiron]

Visser's comments are pretty recent. I was having lunch with him today after he presented his own summary of Horava for a local GR conference.

He is still very positive, saying it is the cutest thing he has seen in 10 years and more promising than the other lines mentioned here. Despite his very clear presentation of Horava, I still don't really have an intuitive understanding of what it is about though.

He gave a thumbs up to Volovik, thumbs down to Nottale, lots of other interesting comments about this and that.

 

[MTd2]

DO YOU KNOW MATT VISSER PERSONALLY??!?

 

[apeiron]

DO YOU KNOW MATT VISSER PERSONALLY??!?

No, I write about science so was interviewing him.

 

[qsa]

I vote for rovolli since I have conjectured that lattice theory is linked to spin foam( and found later that they are daul). Moreover, lattice theory is also linked to String theory(ising model) and CDT looks like it sits in them middle of them all. AsymSafe looks far on the face of it but I think it is closer to them than one might think. My own Idea links them all, where space-time and matter are one and the same virtually. And it is basically of Ising type model. In a paper I read some months back by Baez he was disappointed when he discovered that a more powerfull theory led to space-time elements(ds^2) to run to much larger than Planck's length. I think he has made a big mistake by dissmissing such results.

http://www.qsa.netne.net

 

[marcus]

...
So far nine people have responded!: eight on the original poll plus Arivero with a "write in" vote for SUGRA.

5 for Loop (Christine, MTd2, tom.stoer, SW VandeCarr, marcus)
2 for AsymSafe (william donnelly, marcus)
2 for SUGRA (arivero, tom.stoer)
2 for CDT (marcus, BigF)
1 for Regge (marcus)
1 for Xiao-Gang Wen ('Sabah)

Thanks to all who have responded so far!

To update at yearend, 12 of us have so far registered what we see as the most promising approaches.
Eleven on the regular poll, making twelve counting Arivero's "write-in" vote for supergravity, which I neglected to include at the start.

6 for Loop (Christine, MTd2, tom.stoer, SW VandeCarr, qsa, marcus)
3 for AsymSafe (garrett, william donnelly, marcus)
2 for SUGRA (arivero, tom.stoer)
2 for CDT (marcus, BigF)
1 for Horava (apeiron)
1 for Regge (marcus)
1 for Xiao-Gang Wen ('sabah)

===============
EDIT, there was still time to edit, so I have added two votes as requested in next post #111.
Horava is now 1+1
AsymSafe is now 3+1

6 for Loop (Christine, MTd2, tom.stoer, SW VandeCarr, qsa, marcus)
4 for AsymSafe (garrett, william donnelly, MTd2, marcus)
2 for SUGRA (arivero, tom.stoer)
2 for CDT (marcus, BigF)
2 for Horava (apeiron, MTd2)
1 for Regge (marcus)
1 for Xiao-Gang Wen ('sabah)

 

[MTd2]

If it possible include 1 for HG and 1 for AS

 

[marcus]

If it possible include 1 for HG and 1 for AS

Done.

 

[ensabah6]

Should LHC find evidence of SUSY, is there a need for there to be a "successor" to string theory? (on the other hand, if LHC does not find such evidence, I wonder what would become of strings)