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Our picks for third quarter 2009 MIP (most important QG paper)

  1. Ashtekar et al.

    33.3%
  2. 't Hooft

    66.7%
  3. Benedetti et al.

    16.7%
  4. Lewandowski et al.

    50.0%
  5. Christensen et al.

    16.7%
  6. Dittrich et al.

    33.3%
  7. Woodard

    16.7%
  8. Krasnov

    66.7%
  9. Barrett et al.

    33.3%
Multiple votes are allowed.
  1. Sep 30, 2009 #1

    marcus

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    Of these nine candidates, please indicate the paper or papers which you think will contibute most significantly to future research in 4D quantum gravity. Multiple choice is possible in the poll, so pick several if you wish.

    http://arxiv.org/abs/0909.4221 Ashtekar, Campiglia, Henderson
    http://arxiv.org/cits/0909.4221 Loop Quantum Cosmology and Spin Foams

    http://arxiv.org/abs/0909.3426 't Hooft
    http://arxiv.org/cits/0909.3426 Quantum Gravity without Space-time Singularities or Horizons

    http://arxiv.org/abs/0909.3265 Benedetti, Machado, Saueressig
    http://arxiv.org/cits/0909.3265 Four-Derivative Interactions in Asymptotically Safe Gravity

    http://arxiv.org/abs/0909.0939 Lewandowski, Kamiński, Kisielowski
    http://arxiv.org/cits/0909.0939 Spin-Foams for All Loop Quantum Gravity

    http://arxiv.org/abs/0908.4476 Christensen, Khavkine, Livine, Speziale
    http://arxiv.org/cits/0908.4476 Sub-leading Asymptotic Behaviour of Area Correlations in the Barrett-Crane Model

    http://arxiv.org/abs/0907.4323 Dittrich, Bahr
    http://arxiv.org/cits/0907.4323 Improved and Perfect Actions in Discrete Gravity

    http://arxiv.org/abs/0907.4238 Woodard
    http://arxiv.org/cits/0907.4238 How Far Are We from the Quantum Theory of Gravity?

    http://arxiv.org/abs/0907.4064 Krasnov
    http://arxiv.org/cits/0907.4064 Gravity as BF Theory Plus Potential

    http://arxiv.org/abs/0907.2440 Barrett, Dowdall, Fairbairn, Hellmann, Pereira
    http://arxiv.org/cits/0907.2440 Lorentzian Spin Foam Amplitudes: Graphical Calculus and Asymptotics

    I'll try to give a thumbnail for each one, and say why it might prove important. The list is most recent first so I'll review them in that order.
     
    Last edited: Sep 30, 2009
  2. jcsd
  3. Sep 30, 2009 #2

    marcus

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    Brief thumbnail reviews. Most recent papers first.

    http://arxiv.org/abs/0909.4221 Ashtekar, Campiglia, Henderson
    http://arxiv.org/cits/0909.4221 Loop Quantum Cosmology and Spin Foams
    Until now, Loop cosmo has not used the spinfoam approach, but has been based on a simplified version of canonical LQG. But in the full theory, spinfoam has become the principal way dynamics is handled, so it's time to link cosmology to spinfoam.

    http://arxiv.org/abs/0909.3426 't Hooft
    http://arxiv.org/cits/0909.3426 Quantum Gravity without Space-time Singularities or Horizons
    't Hooft chose this for his annual Erice talk. Radical message: spacetime must be represented in the theory, conformal (scale) symmetries rule, and there's a conformal symmetry which turns black holes inside out. Total mind-blower.

    http://arxiv.org/abs/0909.3265 Benedetti, Machado, Saueressig
    http://arxiv.org/cits/0909.3265 Four-Derivative Interactions in Asymptotically Safe Gravity
    The whole AsymSafe program depends on establishing the finite dimensionality of the hypersurface that is attracted towards the UV fixed point, in the renormalization flow. Benedetti et al. carry this program forward, with progressively less restrictive truncation.

    http://arxiv.org/abs/0909.0939 Lewandowski, Kamiński, Kisielowski
    http://arxiv.org/cits/0909.0939 Spin-Foams for All Loop Quantum Gravity
    Rigorously confirms the fit between spin foams and the spin networks of canonical LQG.

    http://arxiv.org/abs/0908.4476 Christensen, Khavkine, Livine, Speziale
    http://arxiv.org/cits/0908.4476 Sub-leading Asymptotic Behaviour of Area Correlations in the Barrett-Crane Model
    Computing spinfoam amplitudes. The old BC model serves as warmup to tackling the new EPRL model. Use is made of Western Ontario's "Beowulf Cluster" supercomputer.

    http://arxiv.org/abs/0907.4323 Dittrich, Bahr
    http://arxiv.org/cits/0907.4323 Improved and Perfect Actions in Discrete Gravity
    Introduces Regge with curved blocks. Exact (not merely approximate) lattice quantum gravity.

    http://arxiv.org/abs/0907.4238 Woodard
    http://arxiv.org/cits/0907.4238 How Far Are We from the Quantum Theory of Gravity?
    A 100-page commissioned review of the whole field. A particle physicist (Sidney Coleman was his PhD advisor) with thorough expertise in General Relativity makes a cool critical assessment of all the various approaches.

    http://arxiv.org/abs/0907.4064 Krasnov
    http://arxiv.org/cits/0907.4064 Gravity as BF Theory Plus Potential
    Longshot. Author walks away from the Holst form of the Lagrangian that everybody else is using. Takes the Plebanski form and extends it to a larger class of actions. Gets something that might accommodate renormalization more completely than the Holst-based spinfoams now being investigated. I like his nerve and think a few outriders who get clear away from the rest of the wagon-train should be encouraged. :biggrin:

    http://arxiv.org/abs/0907.2440 Barrett, Dowdall, Fairbairn, Hellmann, Pereira
    http://arxiv.org/cits/0907.2440 Lorentzian Spin Foam Amplitudes: Graphical Calculus and Asymptotics
    Graphic calculus means inventing something like Feynman diagrams to organize and conceptualize spin foam amplitude calculations. Authors prove that the set of Lorentz rep labels which EPRL chose is actually forced. It would seem to be the only right set of representations to use for labeling spin foams! Firms up the new model's formula for amplitudes.

    Apologies to anyone whose favorite has been missed. I started out with a list of 14 or 15 candidates, all good interesting papers! I had to cut down the list to make a workable poll.
     
    Last edited: Oct 1, 2009
  4. Sep 30, 2009 #3

    marcus

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    I had to take care of something else and didn't vote my picks on the poll until just now. In the mean time Atyy swiftly got in there and voted first :biggrin: Very glad to see we agree on a couple!

    Five of us have registered our picks already. Thanks to everyone who responded!
     
    Last edited: Oct 1, 2009
  5. Oct 28, 2009 #4

    marcus

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    Thanks to everyone who responded so far by listing their choices in the poll!
    It's now almost one month into the fourth quarter. Still too early to gauge the papers' longterm impact, but we can begin to watch the citations to some of the more useful ones mount up. All but two of the 3rd quarter papers on our poll have been cited at least once in other authors' research.

    We can also start to accumulate a list of 4th quarter papers that seem likely candidates for the 4th quarter MIP poll. Here are some October 2009 papers that impressed me personally as potentially important contributions to QG research.

    Percacci http://arxiv.org/abs/0910.5167 (everybody seems interested in this one)
    Gravity from a Particle Physicists' perspective
    Krasnov http://arxiv.org/abs/0910.4028 (MTd2 called special attention to this)
    Metric Lagrangians with two propagating degrees of freedom
    Baratin-Wise http://arxiv.org/abs/0910.1542 (John Baez put the spotlight on this one)
    2-Group Representations for Spin Foams
    Ashtekar et al. http://arxiv.org/abs/0910.1278 (extends quantum cosmology to non-isotropic cases)
    Loop quantum cosmology of Bianchi type II models
    Padmanabhan http://arxiv.org/abs/0910.0839 (observer-dependent entropy)
    A Dialogue on the Nature of Gravity
     
    Last edited: Oct 29, 2009
  6. Oct 29, 2009 #5
    This is very intriguing. If I'm not mistaken:

    ’tHooft:
    spacetime -> non-emergent
    horizons -> observer dependent
    rationale -> add conformal transfs. to symmetry ops.

    Padmanabhan:
    spacetime -> emergent
    horizons -> observer dependent
    rationale -> entropy observer dependent/gravity thermodyn. interpretation

    I think that both these papers are extremely interesting by themselves and fundamental. Both views are intriguing. It would be interesting to see whether they can be conciliated.
     
  7. Dec 23, 2009 #6

    marcus

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    More 4th quarter papers for possible inclusion in poll.

    Ashtekar Sloan http://arxiv.org/abs/0912.4093
    Loop quantum cosmology and slow roll inflation

    Dittrich Höhn http://arxiv.org/abs/0912.1817
    From covariant to canonical formulations of discrete gravity

    Lewandowski Kamiński Kisielowski http://arxiv.org/abs/0912.0540
    The EPRL intertwiners and corrected partition function

    Shaposhnikov Wetterich http://arxiv.org/abs/0912.0208
    Asymptotic safety of gravity and the Higgs boson mass

    EDIT: Krasnov Torres http://arxiv.org/abs/0911.3793
    Gravity-Yang-Mills-Higgs unification by enlarging the gauge group (see post #8)

    {{EDIT: I would like to remove this one, as the less essential of the two Krasnov papers http://arxiv.org/pdf/0911.4903
    Effective metric Lagrangians from an underlying theory with two propagating degrees of freedom}}

    Freidel Livine http://arxiv.org/abs/0911.3553
    The Fine Structure of SU(2) Intertwiners from U(N) Representations

    Thiemann Engle Han http://arxiv.org/abs/0911.3433
    Canonical path integral measures for Holst and Plebanski gravity. I. Reduced Phase Space Derivation

    Weinberg http://arxiv.org/abs/0911.3165
    Asymptotically Safe Inflation

    Rovelli Ding http://arxiv.org/abs/0911.0543
    The volume operator in covariant quantum gravity

    Percacci Narain http://arxiv.org/abs/0911.0386
    Renormalization Group Flow in Scalar-Tensor Theories. I
     
    Last edited: Dec 24, 2009
  8. Dec 24, 2009 #7
    I would have included the Causal Set programme by R.Sorkin.

    But as a string theorist myself I'm really interested in the review by Coleman's student, thank you Marcus.
     
  9. Dec 24, 2009 #8

    atyy

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  10. Dec 24, 2009 #9

    marcus

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    Your recommendation is good. I was wondering which of those two Krasnov's to include.

    At least for now, I'd like to edit and replace my original Krasnov pick by the one you suggest.

    We could generally go over to picking bundles of papers by same author on the same theme (which isn't necessarily bad, we've done that sometimes in the past, but gets cumbersome), or we could stick to listing only one hopefully representative paper.
     
    Last edited: Dec 24, 2009
  11. Dec 24, 2009 #10

    atyy

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    Last edited: Dec 24, 2009
  12. Dec 24, 2009 #11

    marcus

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    You are very welcome, Gianni! Thanks for your comment. I'm glad you found the pointer to Woodard's paper helpful. (I gather he must be the Coleman's student you were referring to.)
    Anyone who wants can still vote their choice(s) in the poll. Woodard's review of the whole scene probably deserves more notice. So far it only got one vote in our poll, but we can hardly pretend to be infallible judges :biggrin:.
     
  13. Dec 24, 2009 #12

    MTd2

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    Hmm, what about that Robert Finkelstein paper?
     
  14. Dec 27, 2009 #13

    marcus

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    It's hard to assess the actual importance. He is over 90 years old. He has written several papers on that general topic, which fail to cite research in the same area by other people. For some reason he seems to be working in isolation. As if out of touch.
    http://personnel.physics.ucla.edu/directory/faculty/index.php?f_name=finkelstein [Broken]
    If this were to change---and if that series of papers started being cited by other researchers---I would feel more confident about gauging its relative importance.
    Here is his output since 1990, showing cites:
    http://www.slac.stanford.edu/spires/find/hep/www?rawcmd=FIND+A+FINKELSTEIN%2C+ROBERT++J+AND+DATE+%3E+1990&FORMAT=www&SEQUENCE=citecount%28d%29 [Broken]
    The titles are interesting--he clearly has interesting ideas. Also the titles are somewhat repetitive, recycling the same interesting topical keywords. I have to reserve judgement. Hard to assess.
     
    Last edited by a moderator: May 4, 2017
  15. Dec 27, 2009 #14

    MTd2

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    The importance I see in this approach, as I stated a long time ago, is on finding a way that can goes around Coleman Mandula, without supersymmetry. The only way know, as far as I know, is using quantum groups. I don't know why this is the only way, but it is stated in wikipedia ( :biggrin: ), and sounds like beating the string theorists on their own game.
     
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