2007 Paper of the Year (A+ for leadership ability )

[marcus]

2007 Paper of the Year (A+ for "leadership ability")

in junior high school they started telling us about "leadership ability" which apparently was exemplified by some guy who was good at sports, didn't bug the teachers, and was perhaps a bit cleaner than usual. It certainly wasn't clear to me what "leadership ability" meant, but we were supposed to develop it and be recognized for it. Now I realize that it is a quality which a technical research paper can have, but rarely does.

It's pretty obvious now in nonstring QG what the 2007 paper of the year is going to be. It came out 1 November and tops everything from the first ten months, in terms of future significance of the research. Not only that, it also manages to be clearly written in only 8 pages!

But the paper also has some other quality.

It does something that a pure theory research paper isn't usually expected to do.

It tells a story which heals and unifies a community of ideas that was showing signs of conflict. It puts things together. That is why it is an especially interesting paper.

Also Etera, who posts here sometimes, is on board with this one.

A brilliant stroke, so brilliant I almost hold my breath and don't mention, is citing Thiemann Master Constraint as a precursor to the two key EPR papers.

http://arxiv.org/abs/0711.0146

The story it tells is inclusive, everybody has a part, and it fits together several disparate things that weren't fitting together before:
spinfoam, the discrete area spectrum, the immirzi, the lorentzian version, the canonical ancestor LQG...

We have two more months left in 2007. Let's see if anything appears that tops this.

 

[Chronos]

It is a truly remarkable paper, marcus. Topping this one will not be easy.

 

[marcus]

It is a truly remarkable paper, marcus. Topping this one will not be easy.

I'm glad you agree! Renate Loll is still in there kicking BTW. Did you see her latest?
========================

I'm going to try to describe a MAP (a perspective or outline) of non-string QG. Hopefully it will help put things in context. At the moment (because of review papers by Krasnov, Loll, Percacci) it is easy to say where some of the main non-Loop approaches are. So it is a good time to draw the map.

Three main sectors of Loop-community work:

1. Marseille new vertex
suggested review = what I'm saying will probably be paper of the year

2. Penn State cosmology
suggested review = Ashtekar's latest
new feature = Bojowald on big bang nucleosynthesis

3. Perimeter braid network combining geometry and matter states
no review, but see recent papers by Smolin and Wan
work in preparation by Bilson-Thompson, Hackett, Kauffman

Three related non-discrete QG approaches betting on asymptotic safety

1. Legoblock path integral
Loll's review just came out
(CDT let's the size of the blocks go to zero)

2. Running couplings--going with the flow
Percacci's review called, appropriately enough, "Asymptotic Safety"
(Reuter-Percacci let the energy scale k go to infinity)

3. Hodge star gravity, where the Hodge dual replaces metric d.o.f.
Krasnov's review just came out "Non-metric gravity: a status report"
(see section 3 on Renormalizability)

Invisible horses
Garrett Lisi representing geometry + matter with an exceptional group E8 connection
Jesper Grimstrup's combining QG with Connes NCG standard particle model
=======================

Here are some links

Marseille new vertex:
http://arxiv.org/abs/0711.0146
https://www.physicsforums.com/showthread.php?t=194651

Perimeter braid network describing matter and geometry:
http://arxiv.org/abs/0710.1548
https://www.physicsforums.com/showthread.php?t=190053

Penn State quantum cosmology:
http://arxiv.org/abs/0710.3565
https://www.physicsforums.com/showthread.php?t=194678
https://www.physicsforums.com/showthread.php?t=194994

Utrecht Legoblock path integral:
http://arxiv.org/abs/0711.0273
https://www.physicsforums.com/showthread.php?t=196244

Mainz-Trieste Fixed-point gambit:
http://arxiv.org/abs/0709.3851

Krasnov non-metric (i.e. Hodge star) gravity:
http://arxiv.org/abs/0711.0697
https://www.physicsforums.com/showthread.php?t=158899

I'm leaving out lots of interesting work (Baez, Wise, Perez, Thiemann, Dittrich,...)
Hard to see the field in its entirety. This outline fails to emphasize the importance of numerical work (Loll's group, Christensen's, Rideout's...)

======EDIT TO REPLY TO NEXT POST======
Grosquet, you are quite right. Andy Randono just recently posted his PhD thesis: work on validating the Kodama state. I have left this out along with some other interesting work (Baez, Wise, Perez, Thiemann, Dittrich,...) I mentioned. I will get that Randono link, to have here as a reminder.
http://arxiv.org/abs/0709.2905
In Search of Quantum de Sitter Space: Generalizing the Kodama State
Andrew Randono
Ph.D. dissertation, University of Texas at Austin. 150 pages
(Submitted on 18 Sep 2007)

 

[grosquet]

Marcus:
You mentioned in previous threads, Randono's work on Kodama & the Immirzi parameter. I was wondering how that relates to this new paper. I'm a LQG fan who has read Smolin's LQG chapter in 3 Roads to Quantum Gravity many times, & of course all the great information you provide here on the entire LQG field in many threads.

 

[Chronos]

I really like Loll's concept. It is elegant, but not uniform. Fractal spacetime makes perfect sense to me.

 

[marcus]

I really like Loll's concept...

I do too! It sets the bar high for would-be fundamental theories of spacetime.
If you go by Loll's standard the theory oughtn't even take the dimensionality of space for granted---even the largescale three-dee-ness of it has to emerge dynamically.

BTW I was glad to see you registered a prediction. I now think that you and Packard are likely to be proven right.

 

[marcus]

...
I'm going to try to describe a map ...of non-string QG. Hopefully it will help put things in context.

Three main sectors of Loop-community work:

1. Marseille new vertex
suggested review = what I'm saying will probably be paper of the year

2. Penn State cosmology
suggested review = Ashtekar's latest
new feature = Bojowald on big bang nucleosynthesis

3. Perimeter braid network combining geometry and matter states
no review, but see recent papers by Smolin and Wan
work in preparation by Bilson-Thompson, Hackett, Kauffman

Four related non-discrete QG approaches betting on asymptotic safety

1. Legoblock path integral
Loll's review just came out
(CDT let's the size of the blocks go to zero)

2. Running couplings--going with the flow
Percacci's review called, appropriately enough, "Asymptotic Safety"
(Reuter-Percacci let the energy scale k go to infinity)

3. Hodge star gravity, where the Hodge dual replaces metric d.o.f.
Krasnov's review just came out "Non-metric gravity: a status report"
(see section 3 on Renormalizability)

4. E8 gravity+matter---- Lisi structure, representing geometry + matter with an E8 connection

Invisible horse
Jesper Grimstrup's combining QG with Connes NCG standard particle model
=======================

I edited this map from the earlier post. I'm wondering if it is kind to the subject matter to divide the approaches up this way. Grouping them in small clusters makes them easier to remember and assimilate but it may obscure too.
Is it fair to say that LQG approaches assume a fundamental scale-----some structure down there that you can't go smaller than?

And the other approaches, don't they all avoid posing a limit to how small? so that in some sense the latter group help each other. If Reuter-Percacci asymptotic safety gains credibility that also lends some extra to Lisi.

Loll doesn't have a limit to how small, either, unless I misunderstand. In her construction you let the block size go to zero.
============

Mentally I put a large bet on Rovelli's 1 November paper, for being the year's most significant in QG.
And as soon as I did that, almost the next day, two new papers appeared
Renate Loll's
Garrett Lisi's

Now I'm much less confident about my initial nomination. If I'd known about the other two I might have proposed a three-way race. There is a redface smilie symbol around here somewhere. Yes, here it is