# Most Influential Paper third quarter 2006

## Which 3rd quarter papers do you predict will prove most valuable to future research?

15.4%

30.8%

0 vote(s)
0.0%

53.8%
1. Oct 2, 2006

### marcus

Which of these do you expect to have the greatest future influence on research? Papers are listed alphabetically by author.

A. Barrett and Connes
These are paired in the poll, since Barrett and Connes arrived at the same result at the same time.

http://arxiv.org/abs/hep-th/0608221
A Lorentzian version of the non-commutative geometry of the standard model of particle physics
Barrett

http://arxiv.org/abs/hep-th/0608226
Noncommutative Geometry and the standard model with neutrino mixing
Connes

B. Freidel et al

http://arxiv.org/abs/gr-qc/0607014
Particles as Wilson lines of gravitational field
Freidel, Kowalski-Glikman, Starodubtsev
19 pages, to be published in Phys. Rev. D

"Since the work of Mac-Dowell-Mansouri it is well known that gravity can be written as a gauge theory for the de Sitter group. In this paper we consider the coupling of this theory to the simplest gauge invariant observables that is, Wilson lines. The dynamics of these Wilson lines is shown to reproduce exactly the dynamics of relativistic particles coupled to gravity, the gauge charges carried by Wilson lines being the mass and spin of the particles. Insertion of Wilson lines breaks in a controlled manner the diffeomorphism symmetry of the theory and the gauge degree of freedom are transmuted to particles degree of freedom."

C. Gambini et al

http://arxiv.org/abs/quant-ph/0608243
Relational physics with real rods and clocks and the measurement problem of quantum mechanics
Rodolfo Gambini, Jorge Pullin
19 pages

"The use of real clocks and measuring rods in quantum mechanics implies a natural loss of unitarity in the description of the theory. We briefly review this point and then discuss the implications it has for the measurement problem in quantum mechanics. The intrinsic loss of coherence allows to circumvent some of the usual objections to the measurement process as due to environmental decoherence."

D. Smolin

http://arxiv.org/abs/quant-ph/0609109
Could quantum mechanics be an approximation to another theory?
Lee Smolin
10 pages

"We consider the hypothesis that quantum mechanics is an approximation (accurate only for the description of subsystems of the universe) to another, cosmological theory. Quantum theory is then to be derived from the cosmological theory by averaging over variables which are not internal to the subsystem, which may be considered non-local hidden variables. We find conditions for arriving at quantum mechanics through such a procedure. The key lesson is that the effect of the coupling to the external degrees of freedom introduces noise into the evolution of the system degrees of freedom, while preserving a notion of averaged conserved energy and time reversal invariance.

These conditions imply that the effective description of the subsystem is Nelson's stochastic formulation of quantum theory. We show that Nelson's formulation is not, by itself, a classical stochastic theory as the conserved averaged energy is not a linear function of the probability density. We also investigate an argument of Wallstrom posed against the equivalence of Nelson's stochastic mechanics and quantum mechanics and show that, at least for a simple case, it is in error."

2. Oct 2, 2006

3. Oct 2, 2006

### CarlB

These are all remarkable papers likely to be influential. Was there something in the water these past three months? I picked Smolin's because his paper brings in Nelson and Bohm's versions of QM and could breathe new life into these programs.

4. Oct 2, 2006

### marcus

the first person to make a forecast, and the first to say Smolin "QM as approximation" paper, was Turbo
I think he does what his animal tells him.
It looks a bit like a raccoon, but it isn't
https://www.physicsforums.com/showpost.php?p=957764&postcount=9

I just followed their example
(I'd been reading it and got excited.)

Last edited: Oct 2, 2006
5. Oct 2, 2006

### bananan

I voted Freidel's paper b/c it could give Bilson's ribbons preons a more concrete theoretical basis and allow calculations for particle masses from first principles. Spin and mass-energy and 2nd/3rd generations seem to be unaccounted for with the current preon models. I've suggested Yershov ground his preons in similar models.

Last edited: Oct 2, 2006
6. Oct 2, 2006

### Chronos

Another vote for Smolin. It's an admittedly emotional choice that appeals to my deep seated uneasiness with the inability to reconcile QM with GR. The title is ironic, IMO, because QM is all about approximations. Smolin has a delightful sense of humor.

7. Oct 3, 2006

### marcus

I have to say the response to the poll was wonderful (more than past poll's early days) and took a completely unexpected turn!

thanks all who offered predictions.

==forecasts so far==
Which 3rd quarter papers do you predict will prove most valuable to future research?

Code (Text):
Barrett's and Connes' (a pair)      0%

Freidel et al.'s        bananan, etera  33.33%

Gambini and Pullin's        0%

Smolin's          CarlB, Chronos, marcus, turbo-1   66.67%

===

I was thinking a Connes/Barrett landslide

BTW there was a rumor or guess that Freidel's next paper (with Aristide Baratin) might be appearing in early October, which is now. Hope it does.

The idea of including the Gambini et al, what prompted it, was the ripples or repercussions of what is in that paper are showing up in the latest Jacques Distler paper---and a frequent junior co-author of Gambini/Pullin is one of Distler's co-authors. Actually he has come here and posted sometimes---IIRC in 2004 anyway sometime back. As a PF poster he should get a little resonance

Last edited: Oct 3, 2006
8. Oct 3, 2006

### turbo

You won't go wrong by listening to me and the "real" Turbo. I am (and he was) incredibly motivated by curiosity about how stuff works. Right now, I see the "hot spot" as the intersection of LQG as defined by Lee and Fotini and the quantum vacuum as defined by Venkata. If you will add the work of Antonio, you're working toward real mechanics for QG. If you're following loop quantum gravity, you probably know who all these people are. If you are not, you are probably too stringy to appreciate the references.

Last edited: Oct 3, 2006
9. Oct 13, 2006

### marcus

as it happens, Perimeter just posted a video today which is of Smolin explaining his idea of a deeper pre-quantum cosmology
that quantum mechanics is a small-system approximation to.

It is a one hour talk with the same title as the paper.
It has a lot more pictures and helps to understand the paper.

At the talk, Anthony Valentini asked a question at the end and also Bianca Dittrich did. There were half a dozen other interesting questions, you may recognize people that i didn't. I think maybe John Moffatt was one.

In our poll, so far 7 people made predictions and 4 out of the 7 predicted a big influence for this paper that the video talk is about:

http://arxiv.org/abs/quant-ph/0609109
Could quantum mechanics be an approximation to another theory?
Lee Smolin
so that is a good thing for those people, because they get more explanation clarifying the paper.

to get the video go here
http://streamer.perimeterinstitute.ca:81/mediasite/viewer/
and click on "seminar series"
================

BTW I guessed that Turbo was talking about Anthony Valentini, but he could have meant some other Anthony.

Last edited by a moderator: Apr 22, 2017
10. Nov 17, 2006

### marcus

So far 10 people registered their prediction of what would turn out to be the most influential QG paper of 3rd quarter.

https://www.physicsforums.com/poll.php?do=showresults&pollid=932 [Broken]

Arivero, who has a good track record for guessing, said Alain Connes paper.
Or rather it was a package of Connes and Barrett's papers that came out simultaneously and both showed how to get the Standard Model with neutrinos out of spectral geometry.

Etera Livine who knows QG research from inside (he is at Lyon now)---and two others: Bananan and Energex---predicted it would be the paper of Freidel Kowalski-Glikman and Starodubtsev

http://arxiv.org/abs/gr-qc/0607014
Particles as Wilson lines of gravitational field
19 pages, to be published in Phys. Rev. D
This at least has the merits of not being a toy model (it is full 4D) and of showing how matter can arise from the underlying entity of the gravitational field.

Six others, including myself (3trQN, CarlB, Chronos, marcus, pelastration, turbo-1) bet that the most important paper would be Smolin's

Last edited by a moderator: May 2, 2017
11. Nov 17, 2006

### CarlB

Smolin took 60% of the vote.

What we have here is a breaking up of the consolidation among matter at the foundations of physics. A landslide. Or would that be a "mandate"?

12. Nov 17, 2006

### arivero

I still think that Connes - Barrett will be influential, but surely it will not reflect in citations because at the end the citations will be to the older papers and to the book to appear next year.

13. Nov 17, 2006

### arivero

About that title, "QM as an aproximation", I think it is misleading mathematically. If you think technically, you can say that QM is an aproximation to classical mechanics.

14. Dec 19, 2006

### marcus

Nominations for the October-December Poll

Nominations for the fourth quarter? Good words for any of these? Others you think should be on the ballot?
This is primarily for background independent QG preprints appearing October through December 2006.

http://arxiv.org/abs/hep-th/0611042
Hidden Quantum Gravity in 4d Feynman diagrams: Emergence of spin foams
Aristide Baratin, Laurent Freidel
28 pages, 7 figures

"We show how Feynman amplitudes of standard QFT on flat and homogeneous space can naturally be recast as the evaluation of observables for a specific spin foam model, which provides dynamics for the background geometry. We identify the symmetries of this Feynman graph spin foam model and give the gauge-fixing prescriptions. We also show that the gauge-fixed partition function is invariant under Pachner moves of the triangulation, and thus defines an invariant of four-dimensional manifolds. Finally, we investigate the algebraic structure of the model, and discuss its relation with a quantization of 4d gravity in the limit where the Newton constant goes to zero."
====================

http://arxiv.org/abs/gr-qc/0612071
Plebanski Theory and Covariant Canonical Formulation
Sergei Alexandrov, Eric Buffenoir, Philippe Roche
18 pages

"We establish an equivalence between the Hamiltonian formulation of the Plebanski action for general relativity and the covariant canonical formulation of the Hilbert-Palatini action. This is done by comparing the symplectic structures of the two theories through the computation of Dirac brackets. We also construct a shifted connection with simplified Dirac brackets, playing an important role in the covariant loop quantization program, in the Plebanski framework. Implications for spin foam models are also discussed."

===================
http://arxiv.org/abs/gr-qc/0611154
MacDowell-Mansouri gravity and Cartan geometry
Derek K. Wise
34 pages, 5 figures

"The geometric content of the MacDowell-Mansouri formulation of general relativity is best understood in terms of Cartan geometry. In particular, Cartan geometry gives clear geometric meaning to the MacDowell-Mansouri trick of combining the Levi-Civita connection and coframe field, or soldering form, into a single physical field. The Cartan perspective allows us to view physical spacetime as tangentially approximated by an arbitrary homogeneous 'model spacetime', including not only the flat Minkowski model, as is implicitly used in standard general relativity, but also de Sitter, anti de Sitter, or other models. A 'Cartan connection' gives a prescription for parallel transport from one 'tangent model spacetime' to another, along any path, giving a natural interpretation of the MacDowell-Mansouri connection as 'rolling' the model spacetime along physical spacetime. I explain Cartan geometry, and 'Cartan gauge theory', in which the gauge field is replaced by a Cartan connection. In particular, I discuss MacDowell-Mansouri gravity, as well as its recent reformulation in terms of BF theory, in the context of Cartan geometry."

=============
http://arxiv.org/abs/hep-th/0610241
Gravity and the standard model with neutrino mixing
Ali H. Chamseddine, Alain Connes, Matilde Marcolli
71 pages, 7 figures

"We present an effective unified theory based on noncommutative geometry for the standard model with neutrino mixing, minimally coupled to gravity. The unification is based on the symplectic unitary group in Hilbert space and on the spectral action. It yields all the detailed structure of the standard model with several predictions at unification scale. Besides the familiar predictions for the gauge couplings as for GUT theories, it predicts the Higgs scattering parameter and the sum of the squares of Yukawa couplings. From these relations one can extract predictions at low energy, giving in particular a Higgs mass around 170 GeV and a top mass compatible with present experimental value. The geometric picture that emerges is that space-time is the product of an ordinary spin manifold (for which the theory would deliver Einstein gravity) by a finite noncommutative geometry F. The discrete space F is of KO-dimension 6 modulo 8 and of metric dimension 0, and accounts for all the intricacies of the standard model with its spontaneous symmetry breaking Higgs sector. "
================

http://arxiv.org/abs/hep-th/0612170
From noncommutative kappa-Minkowski to Minkowski space-time
Laurent Freidel, Jerzy Kowalski-Glikman, Sebastian Nowak
6 pages

"We show that free kappa-Minkowski space field theory is equivalent to a relativistically invariant, non local, free field theory on Minkowski space-time. The field theory we obtain has in spectrum a relativistic mode of arbitrary mass m and a Planck mass tachyon. We show that while the energy momentum for the relativistic mode is essentially the standard one, it diverges for the tachyon, so that there are no asymptotic tachyonic states in the theory. It also follows that the dispersion relation is not modified, so that, in particular, in this theory the speed of light is energy-independent."

Last edited: Dec 19, 2006
15. Dec 20, 2006

### Chronos

Dammit, marcus, you make the choice too hard. These are all fascinating papers. I am partial to the last one you listed.

16. Dec 20, 2006

### marcus

thanks! in that case I will be sure to include it.
We don't have to put all of these titles on the poll itself.
It should be an interesting range of choice but not overwhelming.
So these are just some ideas for ones to include.
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