# Choice for 3rd quarter MIP (most important QG paper)

## Which paper(s) will prove most valuable to future research?

100.0%

50.0%

50.0%

0 vote(s)
0.0%

25.0%

25.0%
1. Oct 1, 2008

### marcus

Which of these 3rd quarter 2008 papers do you predict will prove most valuable to future research? Significant papers tend to be cited more in subsequent research---we will soon have citation counts to go by, on some of these, as well as subjective judgment. Polling lets us share information as to which lines of research we think most promising or important.

http://arxiv.org/abs/0809.4464
Effective Theory of Braid Excitations of Quantum Geometry in terms of Feynman Diagrams
Yidun Wan
24 pages, 7 figures
(Submitted on 25 Sep 2008)

http://arxiv.org/abs/0809.2280
On the semiclassical limit of 4d spin foam models
32 pages, 5 figures
(Submitted on 15 Sep 2008)

http://arxiv.org/abs/0807.4481
The Nonperturbative Quantum de Sitter Universe
J. Ambjorn, A. Goerlich, J. Jurkiewicz, R. Loll
37 pages, many figures, Physical Review D 78 063544 (2008)
(Submitted on 28 Jul 2008)

http://arxiv.org/abs/0809.3190
Evaluation of new spin foam vertex amplitudes
Igor Khavkine
19 pages, 4 figures
(Submitted on 18 Sep 2008)

http://arxiv.org/abs/0809.2590
Physical time and other conceptual issues of QG in the example of LQC
Wojciech Kaminski, Jerzy Lewandowski, Tomasz Pawlowski
18 pages, 1 figure
(Submitted on 15 Sep 2008)

http://arxiv.org/abs/0808.0701
Effective theory for the cosmological generation of structure
Martin Bojowald, Aureliano Skirzewski
8 pages, 1 figure, Advanced Science Letters 1 (2008) 92-98
(Submitted on 5 Aug 2008)

2. Oct 1, 2008

### MTd2

I didn't read Lewandowski properly, I just notice this articles 10 minutes ago, but it surely has some important ideas. I will elaborate on this later.

3. Oct 2, 2008

### marcus

Thanks to all who responded so promptly!
About citations---they obviously don't tell the whole story about a paper's importance, just a part of it. And there is sort of a 6 month delay. It takes time for the other researchers to follow up a lead and prepare papers that cite the given one. It could take any where from a couple of months to a year before we get any indication of how much a paper will be cited by other researchers. But nevertheless I'm going to list the links to get cite counts for these papers immediately, to have them handy whenever needed.

http://arxiv.org/cits/0809.4464
http://www-spires.slac.stanford.edu/spires/find/hep/www?rawcmd=c+0809.4464 [Broken]
Effective Theory of Braid Excitations of Quantum Geometry in terms of Feynman Diagrams
Yidun Wan

http://arxiv.org/cits/0809.2280
http://www-spires.slac.stanford.edu/spires/find/hep/www?rawcmd=c+0809.2280 [Broken]
On the semiclassical limit of 4d spin foam models

http://arxiv.org/cits/0807.4481
http://www-spires.slac.stanford.edu/spires/find/hep/www?rawcmd=c+0807.4481 [Broken]
The Nonperturbative Quantum de Sitter Universe
J. Ambjorn, A. Goerlich, J. Jurkiewicz, R. Loll

http://arxiv.org/cits/0809.3190
http://www-spires.slac.stanford.edu/spires/find/hep/www?rawcmd=c+0809.3190 [Broken]
Evaluation of new spin foam vertex amplitudes
Igor Khavkine

http://arxiv.org/cits/0809.2590
http://www-spires.slac.stanford.edu/spires/find/hep/www?rawcmd=c+0809.2590 [Broken]
Physical time and other conceptual issues of QG in the example of LQC
Wojciech Kaminski, Jerzy Lewandowski, Tomasz Pawlowski

http://arxiv.org/cits/0808.0701
http://www-spires.slac.stanford.edu/spires/find/hep/www?rawcmd=c+0808.0701 [Broken]
Effective theory for the cosmological generation of structure
Martin Bojowald, Aureliano Skirzewski

At this point of course all the papers are quite new and the cite counts are mostly still zero. Only three out of the six papers have garnered citations so far.
You can check the links to see which ones were cited and by whom, if you are curious---but I think it is probably too early for it to tell us much at this point.

Last edited by a moderator: Apr 23, 2017 at 4:08 PM
4. Oct 9, 2008

### marcus

It is one of those which has already been cited, even though it came out less than two months ago.

It is a timely paper because it is planned to launch the Planck observatory in April 2009, which is not so far away now.

5. Oct 16, 2008

### marcus

So far four people have responded and entered predictions in the poll.

Some of the papers have been quick to garner citations from other researchers. They only came out in 3rd quarter (July-September) but apparently their findings filled a need in other people's research or seemed otherwise significant.

The Khavkine paper also has three.
The Bojowald Skirzewski has one.

Nobody but me voted for the Bojowald paper. What a lot of people haven't realized, I think, is that Bojowald is now focusing on deriving PREDICTIONS about early universe structure and the microwave background----deriving predictions of observable effects from non-singular quantum cosmology. He may succeed.

And the Planck CMB observatory is planned for launch April 2009.
I have no idea if or how the financial crisis will affect that. Planck is supposed to observe CMB from a station at the sun-earth L2 point---1.5 million km farther from the sun than the earth is. Similar to WMAP. And be able to see more detail.

I think this Bojo-Skirz paper is part of quantum cosmologist preparing for Planck mission getting a better look at the early universe. So I made it one of my picks.

6. Oct 17, 2008

### MathematicalPhysicist

Marcus your sense of humor is superb.

Most valubale paper, are there also drafts in academia?
Who will win the NPA (national physicists' association)?

(-:

7. Oct 17, 2008

### marcus

That's right. There are close analogies between the world-class physics departments and the world of sports.

Everybody knows which the strong departments are, overall or in a specific field. It comes into sharp focus every year at the big annual conferences. The invited speakers tend to come from a small list of top places. Academics are very conscious of their standing in the League.

It has been this way for several centuries. The scholar game is played for peer-respect points, and it's partly a team sport (to be the top department) and partly individual.

If you are a department chairman (-person) then you gain enormous respect if you make smart picks and build up the standing of your department. You have to have an eye for talent and emerging lines of research. You have to pick the most promising postdocs and first-time faculty appointees. You have to know who goes on the hiring committee.

The real game is played with people instead of papers. It isn't just luck that some departments are top world-class and others are just average ordinary. Somebody built them by the picks they made. Recognizing and developing talent is all-important in the various academic Leagues.

What we are playing here, as you may be realizing, is like a kindergarten version---spotting potential in individual papers rather than in people. How well you understand the field, and see what's going on, is shown by how savvy your picks are.

Last edited: Oct 17, 2008
8. Oct 20, 2008

### marcus

The 3rd quarter only ended three weeks ago, at the end of September, and already four out of the six papers have been cited in subsequent research!

The paper on the foam-geometry path integral by Freidel and Conrady has pulled ahead, it has 4 cites already. As of 20 October, the score card reads:

Khavkine 3
Lewandowski et al 1
Bojowald Skirzewsi 1

Curiously, only two of those responding in the poll picked the Freidel Conrady paper as a prospective winner. We don't have to automatically equate a paper's influence and significance with its cite-count, but it's suggestive. And no one can guess the final outcome at this point. One would need a year or more to be reasonably certain.

Last edited: Oct 20, 2008
9. Oct 21, 2008

### MathematicalPhysicist

Oh well, then I shall wait for the game to get to PS3,XBOX and nintendo-64, I guess the appropiate name would be NPA2009, who will the world series? (-:

10. Oct 31, 2008

### marcus

Now that we are already one month into the fourth quarter we can start assembling a short list of nominees for this quarter's MIP.
Two that have impressed me are:
http://arxiv.org/abs/0810.0514
Quantum Space-times: Beyond the Continuum of Minkowski and Einstein
Abhay Ashtekar
31 pages, 6 figures. To appear in the volume Minkowski Space-time: A Hundred Years Later, edited by V. Petkov (Springer-Verlag,Berlin, 2008) commemorating the 100th anniversary of Minkowski's fusion of space and time in to a 4 dimensional space-time continuum
(Submitted on 2 Oct 2008)

"In general relativity space-time ends at singularities. The big bang is considered as the Beginning and the big crunch, the End. However these conclusions are arrived at by using general relativity in regimes which lie well beyond its physical domain of validity. Examples where detailed analysis is possible show that these singularities are naturally resolved by quantum geometry effects. Quantum space-times can be vastly larger than what Einstein had us believe. These non-trivial space-time extensions enable us to answer of some long standing questions and resolve of some puzzles in fundamental physics. Thus, a century after Minkowski's revolutionary ideas on the nature of space and time, yet another paradigm shift appears to await us in the wings."

This reports current status and outlook in quantum cosmology---with thoughtful perspective on how understanding of spacetime has evolved. Incidentally it only appeared a month ago and has already been cited.
The next paper, by Calcagni and one of Ashtekar's postdocs, is interesting because of phenomenological implications. Calcagni has been thinking about what we can expect to observe as tests of nonsingular (bounce) cosmology.

http://arxiv.org/abs/0810.4330
Loop quantum cosmology and tensor perturbations in the early universe
Gianluca Calcagni, Golam Mortuza Hossain
12 pages. Invited contribution to the special issue of Advanced Science Letters on "Quantum gravity, Cosmology and Black Holes"
(Submitted on 23 Oct 2008)

"We study the tensor modes of linear metric perturbations within an effective framework of loop quantum cosmology. After a review of inverse-volume and holonomy corrections in the background equations of motion, we solve the linearized tensor modes equations and extract their spectrum. Ignoring holonomy corrections, the tensor spectrum is blue tilted in the near-Planckian superinflationary regime and may be observationally disfavoured. However, in this case background dynamics is highly nonperturbative, hence the use of standard perturbative techniques may not be very reliable. On the other hand, in the quasi-classical regime the tensor index receives a small negative quantum correction, slightly enhancing the standard red tilt in slow-roll inflation. We discuss possible interpretations of this correction, which depends on the choice of semiclassical state."

The following is a potentially useful review article in a crucial line of investigation. It already has one citation although it's only been out a couple of weeks.
http://arxiv.org/abs/0810.1978
Background-free propagation in loop quantum gravity
Simone Speziale
Invited contribution to a special issue of Advanced Science Letters edited by Martin Bojowald. 14 pages
(Submitted on 10 Oct 2008)

"I review the definition of n-point functions in loop quantum gravity, discussing what has been done and what are the main open issues. Particular attention is dedicated to gauge aspects and renormalization."

Last edited: Nov 1, 2008
11. Nov 14, 2008

### marcus

As of today, 14 November, our 3rd quarter (June-August) papers have 12 cites.
Of the total 5/12 are to Freidel et al.
On the basis of early performance one could single that one out. On the poll, two people picked it.

There are some good physical reasons why Freidel et al is important. It developes a new method for analyzing spinfoams and proving theorems about spinfoam QG models. It shows how to construct a path integral using the dual simplicial complex of the spinfoam. The path integral allows comparison of several proposed spinfoam models, and also brings spinfoam QG into closer relation to Loll-style Triangulation QG. Thus the paper can potentially play a central role in the convergence of QG approaches we see occurring. One doesn't always see the full significance of a paper at first, it can come as an afterthought.

Now that the 4th quarter is half over, we should look over the list of five possible MIP candidates that we have so far.
===========

http://arxiv.org/abs/0810.0514
http://arxiv.org/cits/0810.0514
Quantum Space-times: Beyond the Continuum of Minkowski and Einstein
Abhay Ashtekar
31 pages, 6 figures. To appear in the volume Minkowski Space-time: A Hundred Years Later, edited by V. Petkov (Springer-Verlag,Berlin, 2008) commemorating the 100th anniversary of Minkowski's fusion of space and time in to a 4 dimensional space-time continuum
(Submitted on 2 Oct 2008)

"In general relativity space-time ends at singularities. The big bang is considered as the Beginning and the big crunch, the End. However these conclusions [use] general relativity in regimes which lie well beyond its physical domain of validity. Examples ... show that these singularities are naturally resolved by quantum geometry effects. Quantum space-times can be vastly larger ... These... extensions enable us to answer of some long standing questions and resolve of some puzzles in fundamental physics..."

http://arxiv.org/abs/0810.1978
http://arxiv.org/cits/0810.1978
Background-free propagation in loop quantum gravity
Simone Speziale
Invited contribution to a special issue of Advanced Science Letters edited by Martin Bojowald. 14 pages
(Submitted on 10 Oct 2008)

"I review the definition of n-point functions in loop quantum gravity, discussing what has been done and what are the main open issues. Particular attention is dedicated to gauge aspects and renormalization."

http://arxiv.org/abs/0811.1396
http://arxiv.org/cits/0811.1396
Fractal properties of quantum spacetime
Dario Benedetti
4 pages, 2 figures
(Submitted on 10 Nov 2008)

"We show that in general a spacetime having a quantum group symmetry has also a scale dependent fractal dimension which deviates from its classical value at short scales, a phenomenon that resembles what observed in some approaches to quantum gravity. In particular we analyze the cases of a quantum sphere and of $\k$-Minkowski, the latter being relevant in the context of quantum gravity."

http://arxiv.org/abs/0811.1572
http://arxiv.org/cits/0811.1572
Gauge invariant cosmological perturbation equations with corrections from loop quantum gravity
Martin Bojowald, Golam Mortuza Hossain, Mikhail Kagan, S. Shankaranarayanan
40 pages
(Submitted on 10 Nov 2008)

"A consistent implementation of quantum gravity is expected to change the familiar notions of space, time and the propagation of matter in drastic ways. This will have consequences on very small scales, but also gives rise to correction terms in evolution equations of modes relevant for observations. In particular, the evolution of inhomogeneities in the very early universe should be affected. In this paper consistent evolution equations for gauge-invariant perturbations in the presence of inverse triad corrections of loop quantum gravity are derived. Some immediate effects are pointed out,...
...stringent consistency conditions arise...which will eventually be further constrained observationally."

http://arxiv.org/abs/placeholder [Broken]
Doubly Special Relativity from 4d Spinfoam models, in preparation
F. Girelli, E.R. Livine and D. Oriti
This is one by Etera Livine and friends which was cited in a recent paper as in preparation. It could appear this quarter and would be important for future research. I'm keeping this item as a place holder just in case the paper appears before yearend.

Last edited by a moderator: Apr 23, 2017 at 10:01 PM