# Most Influential Papers second quarter 2006

## Five bundles of papers are listed. Which will prove most valuable to future research?

28.6%

28.6%

14.3%

28.6%
5. ### three by Majid

0 vote(s)
0.0%
1. Jun 29, 2006

### marcus

Here is the choice for the April-June quarter of 2006:

http://arxiv.org/gr-qc/0606061

two by Rovelli
http://arxiv.org/gr-qc/0604044
http://arxiv.org/quant-ph/0604064

two by Ashtekar
http://arxiv.org/gr-qc/0605011
http://arxiv.org/gr-qc/0602086

two by Baez
http://arxiv.org/abs/gr-qc/0605087
http://arxiv.org/abs/math.DG/0511710

three by Majid
http://arxiv.org/hep-th/0604132
http://arxiv.org/hep-th/0604130
http://arxiv.org/hep-th/0601004

To even things up (make forecasting more difficult) I have bundled recent papers in some cases with earlier ones that we have not considered so far.

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Please register your prediction about the impact on future research of these papers. To make it more challenging I have attempted to HANDICAP by bundling papers together.

In the first quarter prediction poll, arivero, Kea, selfAdjoint, and turbo all picked a paper of Padmanabhan which it now turns out is WAY AHEAD of all the others in terms of citations---their pick will very likely prove to have been the most influential when we look back a year from now.

Here is the first quarter forecast thread:

I don't want the same thing to happen without a contest this time. So I will BUNDLE one paper of Padma, against two by Ashtekar, and two by Rovelli, and two by Baez, and so on.

In a given bundle, only ONE of the papers needs to be second quarter (April thru June) and the other or others in the bundle can be earlier ones which we didn't already consider, usually related somehow to the recent one.

Please try to evaluate and weigh the bundles against each other and guess what will turn out over the next year or so to be most influential or in other words the MOST IMPORTANT PACKAGE (MIP) in this case

Last edited: Jun 30, 2006
2. Jun 29, 2006

### marcus

http://arxiv.org/gr-qc/0606061
Gravity: A New Holographic Perspective
Plenary talk at the International Conference on Einstein's Legacy in the New Millennium, December 15 - 22, 2005, Puri, India

2. two by Rovelli
http://arxiv.org/gr-qc/0604044
Graviton propagator in loop quantum gravity
Eugenio Bianchi, Leonardo Modesto, Carlo Rovelli, Simone Speziale
41 pages, 6 figures
"We compute some components of the graviton propagator in loop quantum gravity, using the spinfoam formalism, up to some second order terms in the expansion parameter."
http://arxiv.org/quant-ph/0604064
Relational EPR
Matteo Smerlak, Carlo Rovelli
7 pages
"We argue that EPR-type correlations do not entail any form of 'non-locality', when viewed in the context of a relational interpretation of quantum mechanics. The abandonment of strict Einstein realism advocated by this interpretation permits to reconcile quantum mechanics, completeness, (operationally defined) separability, and locality."

3. two by Ashtekar
http://arxiv.org/gr-qc/0605011
Gravity, Geometry and the Quantum
Abhay Ashtekar
16 pages, 2 figures. To appear in the Proceedings of the Einstein Century Conference, 15-22 July, Paris, edited by J-M Alimi et al (American Institute of Physics)
"After a brief introduction, basic ideas of the quantum Riemannian geometry underlying loop quantum gravity are summarized. To illustrate physical ramifications of quantum geometry, the framework is then applied to homogeneous isotropic cosmology. Quantum geometry effects are shown to replace the big bang by a big bounce. Thus, quantum physics does not stop at the big-bang singularity. Rather there is a pre-big-bang branch joined to the current post-big-bang branch by a 'quantum bridge'. Furthermore, thanks to the background independence of loop quantum gravity, evolution is deterministic across the bridge."
http://arxiv.org/gr-qc/0602086
Quantum Nature of the Big Bang
Abhay Ashtekar, Tomasz Pawlowski, Parampreet Singh
4 Pages, 2 Figures. Minor changes to match the published version in Physical Review Letters
Phys.Rev.Lett. 96 (2006) 141301
"Some long standing issues concerning the quantum nature of the big bang are resolved in the context of homogeneous isotropic models with a scalar field. Specifically, the known results on the resolution of the big bang singularity in loop quantum cosmology are significantly extended as follows: i) the scalar field is shown to serve as an internal clock, thereby providing a detailed realization of the 'emergent time' idea; ii) the physical Hilbert space, Dirac observables and semi-classical states are constructed rigorously; iii) the Hamiltonian constraint is solved numerically to show that the big bang is replaced by a big bounce. Thanks to the non-perturbative, background independent methods, unlike in other approaches the quantum evolution is deterministic across the deep Planck regime."

4. two by Baez
http://arxiv.org/abs/gr-qc/0605087
Quantization of strings and branes coupled to BF theory
John C. Baez, Alejandro Perez
"BF theory is a topological theory that can be seen as a natural generalization of 3-dimensional gravity to arbitrary dimensions. Here we show that the coupling to point particles that is natural in three dimensions generalizes in a direct way to BF theory in d dimensions coupled to (d-3)-branes. In the resulting model, the connection is flat except along the membrane world-sheet, where it has a conical singularity whose strength is proportional to the membrane tension. As a step towards canonically quantizing these models, we show that a basis of kinematical states is given by 'membrane spin networks', which are spin networks equipped with extra data where their edges end on a brane."
http://arxiv.org/abs/math.DG/0511710
Higher Gauge Theory
John C. Baez, Urs Schreiber
"Just as gauge theory describes the parallel transport of point particles using connections on bundles, higher gauge theory describes the parallel transport of 1-dimensional objects (e.g. strings) using 2-connections on 2-bundles. A 2-bundle is a categorified version of a bundle: that is, one where the fiber is not a manifold but a category with a suitable smooth structure. Where gauge theory uses Lie groups and Lie algebras, higher gauge theory uses their categorified analogues: Lie 2-groups and Lie 2-algebras. We describe a theory of 2-connections on principal 2-bundles and explain how this is related to Breen and Messing's theory of connections on nonabelian gerbes. The distinctive feature of our theory is that a 2-connection allows parallel transport along paths and surfaces in a parametrization-independent way. In terms of Breen and Messing's framework, this requires that the "fake curvature" must vanish. In this paper we summarize the main results of our theory without proofs."

5. three by Majid
http://arxiv.org/hep-th/0604132
Algebraic approach to quantum gravity III: noncommmutative Riemannian geometry
Shahn Majid
25 pages, 1 figure, to appear in collection B. Fauser and J. Tolksdorf, eds., Birkhauser
"This is a self-contained introduction to quantum Riemannian geometry based on quantum groups as frame groups, and its proposed role in quantum gravity. Much of the article is about the generalisation of classical Riemannian geometry that arises naturally as the classical limit; a theory with nonsymmetric metric and a skew version of metric compatibilty. Meanwhile, in quantum gravity a key ingredient of our approach is the proposal that the differential structure of spacetime is something that itself must be summed over or 'quantised' as a physical degree of freedom. We illustrate such a scheme for quantum gravity on small finite sets."
http://arxiv.org/hep-th/0604130
Algebraic approach to quantum gravity II: noncommutative spacetime
Shahn Majid
26 pages, 2 figures; book chapter to appear in D. Oriti, ed., Cambridge Univ. Press
"We provide a self-contained introduction to the quantum group approach to noncommutative geometry as the next-to-classical effective geometry that might be expected from any successful quantum gravity theory. We focus particularly on a thorough account of the bicrossproduct model noncommutative spacetimes of the form $[t,x_i]=i \lambda x_i$ and the correct formulation of predictions for it including a variable speed of light. We also study global issues in the Poincaré group in the model with the 2D case as illustration. We show that any off-shell momentum can be boosted to infinite negative energy by a finite Lorentz transformaton."
http://arxiv.org/hep-th/0601004
Noncommutative Harmonic Analysis, Sampling Theory and the Duflo Map in 2+1 Quantum Gravity
L. Freidel, S. Majid
54 pages, 2 figures
"We show that the *-product for U(su2) arising in [Freidel-Livine] in an effective theory for the Ponzano-Regge quantum gravity model is compatible with the noncommutative bicovariant differential calculus previously proposed for 2+1 Euclidean quantum gravity using quantum group methods in [Batista-Majid]. We show that the effective action for this model essentially agrees with the noncommutative scalar field theory coming out of the noncommutative differential geometry. We show that the required Fourier transform essentially agrees with the previous quantum group Fourier transform. In combining these methods we develop practical tools for noncommutative harmonic analysis for the model including radial quantum delta-functions and Gaussians, the Duflo map and elements of noncommutative sampling theory' applicable to the bounded SU2,SO3 momentum groups. This allows us to understand the bandwidth limitation in 2+1 quantum gravity arising from the bounded momentum. We also argue that the the anomalous extra time' dimension seen in the noncommutative differential geometry should be viewed as the renormalisation group flow visible in the coarse graining in going from SU2 to SO3. Our methods also provide a generalised twist operator for the *-product."

Most of these papers have been discussed in current PF threads.

Last edited: Jun 30, 2006
3. Jun 29, 2006

### Kea

You've made it much harder by putting Baez's papers in there, but since Stroop theory is being worked on at an alarming rate, meaning more and more ideas appearing every day, I'm still going with Padmanabhan. Maybe I would anyway. This is not a criticism of Stroops...on the contrary...

Perhaps we should start a Padmanabhan thread. I would like to understand his semiclassical holography better. Of course, his Euler equation is so cohomological it's not funny...no, actually, it's very funny really! Peter Woit told me off for trying to talk about Padmanabhan. I really don't know if he was serious or joking.

Last edited: Jun 29, 2006
4. Jun 30, 2006

### marcus

It was nice of you to be voting in poll already. thx. I am glad to learn I succeeded in making it more challenging to pick the winner.
I would not like to be in P.W. shoes. It must be hard to ride that blog which is bucking like a bronco or a resentful steer at rodeo. He will naturally be apt to tell one off or to delete one's post now and then. It is a fine blog tho.

You have a talk to give somewhere, I forget. Sydney? Cindy? Some Oz place.

My intuition is that you would LIKE me to start a Padma thread for you. Although the logical is for you to start it because you (and selfAdjoint) are the ones qualified to attend to it. Instead of waiting for you or him to start it, since you say we should have one, i will proceed.

Last edited: Jun 30, 2006
5. Jun 30, 2006

### arivero

I am taking a conservative option, but I agree with Kea the asessment is problematic here. Majid, Rovelli, and Baez keep threading very deep research lines, and it is not easy to isolate a single paper in a short period.

6. Sep 20, 2007

### marcus

Arivero, your pick is doing the best so far---judging by cites

Ashtekar's two papers total 38 cites
Rovelli (who Mr. Born2Perform predicted would do well) runs a close second at 36.
Kea's pick, Padmanabhan, has 18 to the paper in question.
My pick, Baez, has 15
Majid has 2.

Citations don't tell the whole story. It's subjective which paper you think makes the most valuable contribution to future research. But at present, if we had to go by a quantitative measure, Arivero wins this one.

One reason these forecast polls are interesting is that we find out who are the best-informed guessers, or the people with a knack for predicting. they are the ones who have won several times already in the ten-or-so we've had.