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Who the top quantum cosmology researchers are

  1. Jun 27, 2007 #1

    marcus

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    By quantum cosmology QC I mean research using a quantized version of the familiar classical Friedman-LeMaitre model used in mainstream cosmology.
    Quantum cosmology is beginning to have an impact on regular cosmology.

    It offers answers to certain puzzles and also prospects of testing QC models by astronomical observation (the prospect of testing has started to attract the attention of phenomenologists: such as Roy Maartens of Portsmouth UK).

    So this is a fairly new research field of growing importance---which had some false starts in the 1970s and 1980s but now seems to be taking off. And accordingly its interesting to try to identify the TOP EXPERTS in it.

    I can supply some names, and check to see what the objective measures are---like publication and citations record---invited talks at major conferences, and so on. But maybe some other posters will have OTHER names they want to propose, and we can check out other people's track records and so on.

    the main thing is to get started with the process.
     
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  3. Jun 27, 2007 #2

    marcus

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    Martin Bojowald is an obvious pick for world's top QC expert. I hadn't checked his cites record on SPIRES but I just did a few minutes ago and here it is

    http://www.slac.stanford.edu/spires...+TOPCITE+50+&FORMAT=www&SEQUENCE=citecount(d)

    He has 15 publications in QC that have each been cited over 50 times----ranging from 147 cites down to 53 cites. That's really good, I think, because QC is a small field and just beginning to be recognized by regular cosmologists and observational astronomers.

    Of course his total publications are way more---well over 100 peerreview journal articles, including 4 in Physical Review D last year---but these are the highly cited ones. His most recent articles have not had time yet to accumulate citations, so they don't show up on this list.
     
  4. Jun 27, 2007 #3

    marcus

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    Before we look for other world-class QC researchers of similar stature, I will give an idea of what Bojowald's research is about. One way to do that is to list these 15 highly cited papers and you can see by the titles and get a rough idea. His work involves things of general interest to cosmologists:
    1. singularity removal (conditions prior to big bang)
    2. inflation (some inflation is an intrinsic result, nothing extra put in by hand)
    3. dark energy (possibiity of explaining accelerated expansion without a "negative pressure" field or other additional assumptions)
    However the third of these topics only emerged this year---so the relevant article hasn't yet had time to make this list.

    1) Absence of singularity in loop quantum cosmology.
    Martin Bojowald (Penn State U.) . CGPG-01-2-1, Feb 2001. 4pp.
    Published in Phys.Rev.Lett.86:5227-5230,2001.
    e-Print: gr-qc/0102069
    Cited 147 times

    2) Mathematical structure of loop quantum cosmology.
    Abhay Ashtekar, Martin Bojowald (Penn State U. & Schrodinger Inst., Vienna) , Jerzy Lewandowski (Warsaw U. & Penn State U. & Schrodinger Inst., Vienna) . CGPG-03-4-4, Apr 2003. 29pp.
    Published in Adv.Theor.Math.Phys.7:233-268,2003.
    e-Print: gr-qc/0304074
    Cited 125 times

    3) Isotropic loop quantum cosmology.
    Martin Bojowald (Penn State U.) . CGPG-02-2-2, Feb 2002. 30pp.
    Published in Class.Quant.Grav.19:2717-2742,2002.
    e-Print: gr-qc/0202077
    Cited 108 times

    4) Inflation from quantum geometry.
    Martin Bojowald (Penn State U.) . CGPG-02-6-2, Jun 2002. 4pp.
    Published in Phys.Rev.Lett.89:261301,2002.
    e-Print: gr-qc/0206054
    Cited 106 times

    5) Dynamical initial conditions in quantum cosmology.
    Martin Bojowald (Penn State U.) . CGPG-01-4-3, Apr 2001. 4pp.
    Published in Phys.Rev.Lett.87:121301,2001.
    e-Print: gr-qc/0104072
    Cited 83 times

    6) The Inverse scale factor in isotropic quantum geometry.
    Martin Bojowald (Penn State U.) . CGPG-01-5-1, May 2001. 17pp.
    Published in Phys.Rev.D64:084018,2001.
    e-Print: gr-qc/0105067
    Cited 82 times

    7) Loop quantum cosmology.
    Martin Bojowald (Penn State U. & Potsdam, Max Planck Inst.) . AEI-2005-185, IGPG-06-1-6, Jan 2006. 104pp.
    Published in Living Rev.Rel.8:11,2005.
    e-Print: gr-qc/0601085
    Cited 67 times

    8) The Semiclassical limit of loop quantum cosmology.
    Martin Bojowald (Pen State U.) . CGPG-01-5-2, May 2001. 10pp.
    Published in Class.Quant.Grav.18:L109-L116,2001.
    e-Print: gr-qc/0105113
    Cited 66 times

    9) Quantization ambiguities in isotropic quantum geometry.
    Martin Bojowald (Penn State U.) . CGPG-02-6-1, Jun 2002. 20pp.
    Published in Class.Quant.Grav.19:5113-5230,2002.
    e-Print: gr-qc/0206053
    Cited 66 times

    10) Homogeneous loop quantum cosmology.
    Martin Bojowald (Penn State U.) . CGPG-03-3-5, Mar 2003. 25pp.
    Published in Class.Quant.Grav.20:2595-2615,2003.
    e-Print: gr-qc/0303073
    Cited 64 times

    11) Quantum symmetry reduction for diffeomorphism invariant theories of connections.
    M. Bojowald, H.A. Kastrup (Aachen, Tech. Hochsch.) . PITHA-99-23, Jul 1999. 44pp.
    Published in Class.Quant.Grav.17:3009-3043,2000.
    e-Print: hep-th/9907042
    Cited 63 times

    12) Cosmological applications of loop quantum gravity.
    Martin Bojowald (Penn State U.) , Hugo A. Morales-Tecotl (Mexico City U., Iztapalapa & ICTP, Trieste) . CGPG-03-6-1, Jun 2003. 42pp.
    To appear in the proceedings of 5th Mexican School on Gravitation and Mathematical Physics: The Early Universe and Observational Cosmology (DGFM 2002), Playa del Carmen, Quintana Roo, Mexico, 24-29 Nov 2002.
    Published in Lect.Notes Phys.646:421-462,2004.
    e-Print: gr-qc/0306008
    Cited 60 times

    13) Loop quantum cosmology, boundary proposals, and inflation.
    Martin Bojowald, Kevin Vandersloot (Penn State U.) . CGPG-03-3-4, Mar 2003. 20pp.
    Published in Phys.Rev.D67:124023,2003.
    e-Print: gr-qc/0303072
    Cited 59 times

    14) Loop quantum cosmology. 4. Discrete time evolution.
    Martin Bojowald (Aachen, Tech. Hochsch.) . PITHA-00-18, Aug 2000. 21pp.
    Published in Class.Quant.Grav.18:1071-1088,2001.
    e-Print: gr-qc/0008053
    Cited 55 times

    15) Loop quantum cosmology: Recent progress.
    Martin Bojowald (Potsdam, Max Planck Inst.) . AEI-2004-017, Feb 2004. 17pp.
    Plenary talk given at 5th International Conference on Gravitation and Cosmology (ICGC 2004), Cochin, India, 5-10 Jan 2004.
    Published in Pramana 63:765-776,2004.
    e-Print: gr-qc/0402053
    Cited 53 times
     
    Last edited: Jun 27, 2007
  5. Jun 29, 2007 #4

    Chronos

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    Permit me to introduce John Barrow, if i may, marcus. He is a populist writer and prolific contributor to QC. He has inked around 100 papers on Arxiv since 1995, many coauthored with more famous names. I wouldn't term him as leading edge, but his papers have influenced my thinking about cosmology.
     
  6. Jun 29, 2007 #5

    marcus

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    Thanks, I'm glad someone suggested a name.
    As it happens I corresponded with John Barrow by snailmail a few years back and he replied very helpfully.
    I hope other people besides yourself suggest some names.

    The trouble with Barrow is, he is not a quantum cosmologist.
    He does not work with a quantized version of the model that is basic to classic cosmology.

    What I am looking for are people that have done RECENT work in the EMERGING FIELD OF QC.
    By recent I'd like it to be at least in this century---so much has happened since 2000.

    If a guy has done recent work in actual Quantum Cosmology (not just classic General Relativity with some add-on quantum fluctuations:smile:) then it doesnt even have to be his full-time interest.

    Ashtekar for example has only specialized in QC for the past 3 years or so, his interests being more general, but we should certainly put him at or near the top.

    So the question I'm asking is Who are today's top QC experts?

    Can't anyone come up with suggestions of people besides Bojowald and Ashtekar?
     
  7. Jun 29, 2007 #6

    marcus

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    Let's get Ashtekar's cites.
    I will limit it to his papers AFTER 1999---so it parallels Bojowald all of whose papers are 2000 or later.
    I will limit it to 50+ cites as I did before with Bojowald. There are 9 papers
    BUT THEY ARE NOT ALL QUANTUM COSMOLOGY SO I WILL LIST THEM FIRST AND THEN SELECT OUT.

    http://www.slac.stanford.edu/spires...+DATE+>+1999&FORMAT=www&SEQUENCE=citecount(d)

    1) Background independent quantum gravity: A Status report.
    Abhay Ashtekar (Penn State U. & Potsdam, Max Planck Inst. & Schrodinger Inst., Vienna) , Jerzy Lewandowski (Warsaw U. & Penn State U. & Potsdam, Max Planck Inst. & Schrodinger Inst., Vienna) . Apr 2004. 126pp.
    Published in Class.Quant.Grav.21:R53,2004.
    e-Print: gr-qc/0404018
    Cited 234 times

    2) Quantum geometry of isolated horizons and black hole entropy.
    A. Ashtekar (Penn State U. & Santa Barbara, KITP) , John C. Baez (UC, Riverside & Penn State U.) , Kirill Krasnov (UC, Santa Barbara & Santa Barbara, KITP) . NSF-ITP-99-153, May 2000. 66pp.
    Published in Adv.Theor.Math.Phys.4:1-94,2000.
    e-Print: gr-qc/0005126
    Cited 186 times

    3) Mathematical structure of loop quantum cosmology.
    Abhay Ashtekar, Martin Bojowald (Penn State U. & Schrodinger Inst., Vienna) , Jerzy Lewandowski (Warsaw U. & Penn State U. & Schrodinger Inst., Vienna) . CGPG-03-4-4, Apr 2003. 29pp.
    Published in Adv.Theor.Math.Phys.7:233-268,2003.
    e-Print: gr-qc/0304074
    Cited 125 times

    4) Isolated horizons: Hamiltonian evolution and the first law.
    Abhay Ashtekar (Penn State U. & Santa Barbara, KITP) , Stephen Fairhurst, Badri Krishnan (Penn State U.) . May 2000. 53pp.
    Published in Phys.Rev.D62:104025,2000.
    e-Print: gr-qc/0005083
    Cited 88 times

    5) Isolated horizons and their applications.
    Abhay Ashtekar, Christopher Beetle, Olaf Dreyer, Stephen Fairhurst, Badri Krishnan (Penn State U.) , Jerzy Lewandowski (Warsaw U. & Penn State U.) , Jacek Wisniewski (Penn State U.) . Jun 2000. 4pp.
    Published in Phys.Rev.Lett.85:3564-3567,2000.
    e-Print: gr-qc/0006006
    Cited 88 times

    6) Isolated and dynamical horizons and their applications.
    Abhay Ashtekar (Penn State U. & Santa Barbara, KITP & Potsdam, Max Planck Inst. & Schrodinger Inst., Vienna) , Badri Krishnan (Potsdam, Max Planck Inst. & Schrodinger Inst., Vienna) . Jul 2004. 77pp.
    Published in Living Rev.Rel.7:10,2004.
    e-Print: gr-qc/0407042
    Cited 66 times

    7) Mechanics of rotating isolated horizons.
    Abhay Ashtekar (Penn State U. & Potsdam, Max Planck Inst.) , Christopher Beetle (Penn State U. & Utah U.) , Jerzy Lewandowski (Warsaw U. & Potsdam, Max Planck Inst.) . Mar 2001. 31pp.
    Published in Phys.Rev.D64:044016,2001.
    e-Print: gr-qc/0103026
    Cited 60 times

    8) Dynamical horizons and their properties.
    Abhay Ashtekar (Penn State U. & Santa Barbara, KITP & Schrodinger Inst., Vienna) , Badri Krishnan (Penn State U. & Potsdam, Max Planck Inst. & Schrodinger Inst., Vienna) . CGPG-03-07-3, NSF-KITP-03-57, Aug 2003. 44pp.
    Published in Phys.Rev.D68:104030,2003.
    e-Print: gr-qc/0308033
    Cited 56 times

    9) Dynamical horizons: Energy, angular momentum, fluxes and balance laws.
    Abhay Ashtekar, Badri Krishnan (Penn State U.) . Jul 2002. 4pp.
    Published in Phys.Rev.Lett.89:261101,2002.
    e-Print: gr-qc/0207080
    Cited 54 times

    Actually Ashtekar has co-authored some very important papers in Loop Quantum Cosmology but they have tended to be quite recent, in 2005 and 2006.
    So his papers have not had time to accumulate a lot of citations. What I find is that there is just ONE highly cited paper specifically in the field of QC.
     
    Last edited: Jun 30, 2007
  8. Jun 30, 2007 #7

    marcus

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    That earlier approach to counting didn't work very well, because much of Ashtekar's specifically quantum cosmology work has been so recent it hasn't had time to accumulate a lot of cites, so I will make the cutoff 35 cites and just list the papers in or related to quantum cosmology. Numbers 4 and 16 deal with the quantum geometry of black holes---a subject which is important to cosmology even though not formally part of the field---so I included them in the list:

    2) Quantum geometry of isolated horizons and black hole entropy.
    A. Ashtekar (Penn State U. & Santa Barbara, KITP) , John C. Baez (UC, Riverside & Penn State U.) , Kirill Krasnov (UC, Santa Barbara & Santa Barbara, KITP) . NSF-ITP-99-153, May 2000. 66pp.
    Published in Adv.Theor.Math.Phys.4:1-94,2000.
    e-Print: gr-qc/0005126
    Cited 186 times

    3) Mathematical structure of loop quantum cosmology.
    Abhay Ashtekar, Martin Bojowald (Penn State U. & Schrodinger Inst., Vienna) , Jerzy Lewandowski (Warsaw U. & Penn State U. & Schrodinger Inst., Vienna) . CGPG-03-4-4, Apr 2003. 29pp.
    Published in Adv.Theor.Math.Phys.7:233-268,2003.
    e-Print: gr-qc/0304074
    Cited 125 times

    10) Quantum nature of the big bang.
    Abhay Ashtekar, Tomasz Pawlowski, Parampreet Singh (Penn State U.) . IGPG-06-2-1, Feb 2006. 4pp.
    Published in Phys.Rev.Lett.96:141301,2006.
    e-Print: gr-qc/0602086
    Cited 48 times

    14) Quantum Nature of the Big Bang: An Analytical and Numerical Investigation. I.
    Abhay Ashtekar (Penn State U. & IUCAA, Pune & Newton Inst. Math. Sci., Cambridge) , Tomasz Pawlowski (Penn State U.) , Parampreet Singh (Penn State U. & IUCAA, Pune) . IGPG-06-03-2, Apr 2006. 59pp.
    Published in Phys.Rev.D73:124038,2006.
    e-Print: gr-qc/0604013
    Cited 41 times

    15) Quantum geometry and gravity: Recent advances.
    Abhay Ashtekar (Penn State U.) . CGPG-11-4, Dec 2001. 24pp.
    Plenary talk given at 16th International Conference on General Relativity and Gravitation (GR16), Durban, South Africa, 15-21 Jul 2001.
    e-Print: gr-qc/0112038
    Cited 39 times

    16) Quantum geometry and the Schwarzschild singularity.
    Abhay Ashtekar (Penn State U. & Potsdam, Max Planck Inst.) , Martin Bojowald (Potsdam, Max Planck Inst. & Penn State U.) . IGPG-05-09-01, AEI-2005-132, Sep 2005. 31pp.
    Published in Class.Quant.Grav.23:391-411,2006.
    e-Print: gr-qc/0509075
    Cited 36 times

    17) Quantum Nature of the Big Bang: Improved dynamics.
    Abhay Ashtekar (Penn State U. & Utrecht U. & Newton Inst. Math. Sci., Cambridge) , Tomasz Pawlowski, Parampreet Singh (Penn State U.) . IGPG-06-7-2, Jul 2006. 40pp.
    Published in Phys.Rev.D74:084003,2006.
    e-Print: gr-qc/0607039
    Cited 35 times
     
  9. Jun 30, 2007 #8

    marcus

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    Another person to consider would be Parampreet Singh
    http://www.slac.stanford.edu/spires...+DATE+>+1999&FORMAT=www&SEQUENCE=citecount(d)
    I will again make the cutoff 35 cites and list only the quantum cosmology papers

    1) Big crunch avoidance in K=1 semiclassical loop quantum cosmology.
    Parampreet Singh (IUCAA, Pune) , Alexey Toporensky (Sternberg Astron. Inst.) . Dec 2003. 5pp.
    Published in Phys.Rev.D69:104008,2004.
    e-Print: gr-qc/0312110
    Cited 61 times

    2) Quantum nature of the big bang.
    Abhay Ashtekar, Tomasz Pawlowski, Parampreet Singh (Penn State U.) . IGPG-06-2-1, Feb 2006. 4pp.
    Published in Phys.Rev.Lett.96:141301,2006.
    e-Print: gr-qc/0602086
    Cited 48 times

    3) Quantum Nature of the Big Bang: An Analytical and Numerical Investigation. I.
    Abhay Ashtekar (Penn State U. & IUCAA, Pune & Newton Inst. Math. Sci., Cambridge) , Tomasz Pawlowski (Penn State U.) , Parampreet Singh (Penn State U. & IUCAA, Pune) . IGPG-06-03-2, Apr 2006. 59pp.
    Published in Phys.Rev.D73:124038,2006.
    e-Print: gr-qc/0604013
    Cited 41 times

    4) Inflationary cosmology and quantization ambiguities in semiclassical loop quantum gravity.
    Martin Bojowald (Potsdam, Max Planck Inst.) , James E. Lidsey, David J. Mulryne (Queen Mary, U. of London, Math. Sci.) , Parampreet Singh (IUCAA, Pune) , Reza Tavakol (Queen Mary, U. of London, Math. Sci.) . AEI-2004-027, Mar 2004. 15pp.
    Published in Phys.Rev.D70:043530,2004.
    e-Print: gr-qc/0403106
    Cited 39 times

    5) Effective state metamorphosis in semi-classical loop quantum cosmology.
    Parampreet Singh (Penn State U.) . IGPG-05-2-2, Feb 2005. 5pp.
    Published in Class.Quant.Grav.22:4203-4216,2005.
    e-Print: gr-qc/0502086
    Cited 37 times

    6) Quantum Nature of the Big Bang: Improved dynamics.
    Abhay Ashtekar (Penn State U. & Utrecht U. & Newton Inst. Math. Sci., Cambridge) , Tomasz Pawlowski, Parampreet Singh (Penn State U.) . IGPG-06-7-2, Jul 2006. 40pp.
    Published in Phys.Rev.D74:084003,2006.
    e-Print: gr-qc/0607039
    Cited 35 times

    Well it turned out that I didn't have to sift any out of the list because all of Parampreet Singh's (35+ cites) papers were clearly in quantum cosmology.

    I don't claim that this mechanism of looking for authors of reasonably highly cited papers in quantum cosmology is a surefire way of finding the experts. But it is one objective measure.

    QC is a new emerging field. When a field of science emerges part of the process of definition is you should be able to say who the experts in it are.
    So far we have three: Martin Bojowald, Abhay Ashtekar, Parampreet Singh.

    With the first two, there are other recognized signs of expert standing.

    They both get invited to give the PLENARY SURVEY TALKS at major international conferences---so they serve as the spokesperson for the field.
    This has now happened too many times for me to keep track of so I won't list all the invited plenary survey talks by Bojowald and Ashtekar.

    Also when Elsevier (major science publishing house) joined with Oxford U. Press to produce an ENCYCLOPEDIA OF SCIENCE they recognized the emerging field of Quantum Cosmology and needed an encyclopedia article about it. So the person they invited to write the article on QC was Martin Bojowald.

    The consistency is part of how science operates (peer-review publication, citations, reputation, plenary talks at conferences, writing the main reference works on the subject...) and how a new field normally shapes up and gains definition.
     
  10. Jul 25, 2007 #9

    marcus

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    I just noticed this comment from another poster:
    the particular comparison with Perlmutter is not too apt because the supernova study was OBSERVATIONAL astronomy, a much larger field, and the Perlmutter et al paper (which had a whole bunch of authors including one I know personally :-) ) announced the historical discovery of accelerated expansion---the "dark energy" effect.

    However the post does call for some kind of quantitative measure. So I will check.
     
    Last edited: Jul 25, 2007
  11. Jul 25, 2007 #10

    marcus

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    thought I'd check up on Bojowald's citations on Spires

    quantum cosmology is a small field, of course, only a few dozen people working in it----but people are joining the field rapidly, I regularly see work by new authors

    On the other hand, because it is still a small field, one doesn't expect the citation numbers to be huge.

    as of today 25 July he had a total of 1225 cites
    to his 50+ cites papers. He has a lot more papers than those so it would make a bigger total but i don't want to bother adding up all those numbers.
    So I just take the papers that individually achieved 50 or more, and add them up.

    Back a month ago 27 June the same total was 1204
    You can see that from post # on this thread.

    So he is getting some 20 cites a month, at present, just on this sample of his papers (the 50+ topcites bunch).
     
    Last edited: Jul 25, 2007
  12. Jul 26, 2007 #11
    Hello Marcus,

    Maybe a weird question, but why is it such a small field ?..
    In my view its certainly one of the most fascinating and complex.

    And Bojowald is certainly one of the most interesting scientists in physics and mathematics these days besides Grigori Perelman !..
     
  13. Jul 29, 2007 #12

    marcus

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    Hi Steve, thanks for your comments and question! QC is indeed a small field and needs to grow. Especially in directions that increase the chance of contact with observations.

    QC has had big name people working in it, Wheeler, DeWitt, Hartle, Hawking but current research doesnt draw so much on the earlier. Hawking advocated something called "Euclidean path integral" in the 1980s and he still touts it publically but he couldnt get other people interested and it went out of style.

    there are some more speculative string-inspired ideas but they dont look to me like they are catching on with real cosmologists.
    there's Veneziano Pre-bigbang and Steinhardt Clashing branes and all sorts of multiverse stuff but it does not seem to get CITED a lot.
    there is a buzz about string cosmology in the string community, and the buzz doesnt seem to spread.

    So what I am looking for are people doing down-to-earth honest-to-God cosmology but quantum-style---where I see them getting noticed by mainstream cosmologists, ever so slightly, and where I see a chance of observational checks developing. Indeed it IS a small field, but is growing fast. Bojowald and Ashtekar are attracting young people so we are seeing a kind of small-base exponential growth phase.
    ====================

    there is someone else I want to add to the list and check out his citation numbers like I did the others----this is Martin Reuter.
    He has on the order of 100 published papers and a handful of them have 100+ cites, but until recently his research WAS NOT IN COSMOLOGY.

    So doing a topcites search is a bit awkward for that reason (you get his very successful earlier papers in HEP and quantum field theory) and also for the reason that there are a MORITZ and a MICHAEL Reuter who also do physics and Spires Engine has not figured out how keep them distinct. All three have signed a lot of their work "M. Reuter"

    At any rate, I've found 5 papers by Reuter which are 50+ cites and have significance for cosmology. And his CURRENT focus is very strong on cosmology. So I think I'll class him as a quantum cosmologist and see how he stacks up compared with Bojowald and the others.
     
  14. Jul 29, 2007 #13

    marcus

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    For comparison I just use a person's highly cited (50+) papers. It saves me trouble cause i have fewer to add up.
    I will total the number of cites and put the number of 50+ papers in parens.

    as a benchmark...

    Bojowald
    27 June total cites 1204 (15 papers)
    25 July 1225 (15)

    Reuter cosmo papers only
    29 July 378 (5)
    ===================

    maybe somebody thinks these numbers are not so big and my attitude is let's see how they grow
    because if there is going to emerge a field, and a research community, in OBSERVATIONAL QUANTUM COSMOLOGY
    then part of it is the identification of significant experts in the field
    and they'll be explaining the running of Newton's G and the running of Lambda and they'll be explaining early inflation and late acceleration and resolving the horizon/structure problems and stuff by deriving PREDICTIONS of what exact inflation and acceleration and CMB signals you should expect as you go deeper into the data. and these people that I am trying to find in this thread are going to have to be organizing and speaking at the conferences----if there is going to be a field of "reality-based" quantum cosmology.

    I'll get the titles of Reuter paper bearing on cosmology that I could find which were 50+ cited. There are many ones which are too recent to have accumulated that many citations yet, but I want some index which is easy for me to compute. the sum here for the 5 papers is 378.

    Time Evolution Of The Cosmological 'Constant' 65
    http://www.slac.stanford.edu/spires/find/hep/www?j=PHLTA,B188,38

    http://arxiv.org/abs/hep-th/9605030
    Nonperturbative Evolution Equation for Quantum Gravity 123
    http://www.slac.stanford.edu/spires/find/hep/www?rawcmd=FIND+EPRINT+HEP-TH/9605030

    http://arxiv.org/abs/hep-th/0002196
    Renormalization group improved black hole spacetimes 67
    http://www.slac.stanford.edu/spires/find/hep/www?rawcmd=FIND+EPRINT+HEP-TH/0002196

    http://arxiv.org/abs/hep-th/0106133
    Cosmology of the Planck Era from a Renormalization Group for Quantum Gravity 63
    http://www.slac.stanford.edu/spires/find/hep/www?rawcmd=FIND+EPRINT+HEP-TH/0106133

    http://arxiv.org/abs/astro-ph/0106468
    Cosmology with Self-Adjusting Vacuum Energy Density from a Renormalization Group Fixed Point
    http://www.slac.stanford.edu/spires/find/hep/www?rawcmd=FIND+EPRINT+ASTRO-PH/0106468
     
    Last edited: Jul 29, 2007
  15. Jul 30, 2007 #14

    Chronos

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    I'm still looking for the next level arising from quantum information theory. Just a hunch.
     
  16. Jul 30, 2007 #15

    hellfire

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    Sorry, but this is clearly not a realistic view. Your contributions to this thread are very valuable, but they are biased by your own personal preferences. I have no problem with that, but it would be better to state it to avoid confusion among the readers.

    String quantum cosmology is a very wide field of research. There are lots of important papers, as you can see in Maurizio Gasperini's home page. Some of these papers are the most cited in quantum cosmology, such as this theoretical one with 500+ cites or this phenomenological one with 100+ cites. Moreover, pre-big-bang cosmology has provided very concrete testable predictions such as the spectrum of the background of gravitational waves. However, you are right that there are important issues that remain open in that models. But this is nothing new for any quantum cosmological model.
     
    Last edited: Jul 30, 2007
  17. Jul 30, 2007 #16

    marcus

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    Thanks for adding more stuff to consider!
    I am certainly not averse to looking at the stringy input to quantum cosmology. The biggie you mention (100+) is Veneziano's "Pre-bigbang Cosmology" paper of 1992. The other you mention is 1995. What has Veneziano done lately?

    Maybe we should do some numbers about Veneziano as a candidate for one of the current QC "leaders"!
    BTW there were some remarks about Veneziano Pre-bang made by prominent string theorists (like Gary Horowitz, Steve Shanker...) at the recent KITP Singularities workshop. IIRC there was no Veneziano talk, although the workshop was primarily run by the string folks. Or if there was, iit somehow got very little notice. I found that indicative. We could check back--the workshop is online--if you want.

    My attitude is not exclusionary, hellfire :smile: I'm delighted to have other names of people to check. If you have some definite candidates, please let me know.

    I'm looking for highly-cited current research activity, so I would like names of people who are doing important work at present. And the view of quantum cosmology here is that you have a quantum version of the FRW model that cosmologists actually use---the kind of quantum cosmology that can make sense to working cosmologists like Roy Maartens. I think you understand what I mean. Maartens has written quite a few papers studying stringy models but when I looked them over a while back I didn't see anything that stands out by way of recent work. I don't think he has considered Veneziano Pre-bang, but he may have and I should take another look.

    thanks for the lead, I will check it out.
    ==============
    Here is how Veneziano stacks up, recent work cosmology-wise

    String Theory and Pre-big bang Cosmology. 2 cites
    M. Gasperini (Bari U. & INFN, Bari) , G. Veneziano (CERN & College de France) . CERN-PH-TH-2007-026, Mar 2007. 29pp.
    e-Print: hep-th/0703055

    Regular two-component bouncing cosmologies and perturbations therein. 13 cites
    V. Bozza (Enrico Fermi Ctr., Rome & Salerno U. & INFN, Naples) , G. Veneziano (CERN & College de France) . CERN-PH-TH-2005-097, Jun 2005. 19pp.
    Published in JCAP 0509:007,2005.
    e-Print: gr-qc/0506040

    Scalar perturbations in regular two-component bouncing cosmologies. 16 cites
    V. Bozza (Enrico Fermi Ctr., Rome & Salerno U. & INFN, Naples) , G. Veneziano (CERN & College de France) . CERN-PH-TH-2005-19, Feb 2005. 4pp.
    Published in Phys.Lett.B625:177-183,2005.
    e-Print: hep-th/0502047

    Cosmological perturbations across a curvature bounce. 28 cites
    M. Gasperini (Bari U. & INFN, Bari & Santa Barbara, KITP) , Massimo Giovannini (CERN) , G. Veneziano (Santa Barbara, KITP & CERN) .
    BA-TH-03-465, CERN-TH-2003-257, NSF-KITP-04-07, Jan 2004. 36pp.
    This research was supported in part by the National Science Foundation under Grant No. PHY99-07949.
    Published in Nucl.Phys.B694:206-238,2004.
    e-Print: hep-th/0401112

    A Model for the big bounce. 10 cites
    G. Veneziano (CERN) . CERN-TH-2003-304, Dec 2003. 10pp.
    Published in JCAP 0403:004,2004.
    e-Print: hep-th/0312182

    Perturbations in a nonsingular bouncing universe. 33 cites
    M. Gasperini (Bari U. & INFN, Bari) , Massimo Giovannini, G. Veneziano (CERN) . BA-TH-03-463, CERN-TH-2003-128, Jun 2003. 15pp.
    Published in Phys.Lett.B569:113-122,2003.
    e-Print: hep-th/0306113

    Cosmological perturbations from a new physics hypersurface. 51 cites (THERE WE GO, something in the 50+)
    V. Bozza (Salerno U. & INFN, Naples & Frascati) , Massimo Giovannini, G. Veneziano (CERN) . CERN-TH-2003-041, Feb 2003. 13pp.
    Published in JCAP 0305:001,2003.
    e-Print: hep-th/0302184

    Constraints on pre big bang parameter space from CMBR anisotropies. 19 cites
    V. Bozza (Salerno U. & INFN, Salerno & CERN) , M. Gasperini (Bari U. & INFN, Bari) , Massimo Giovannini, G. Veneziano (CERN) . BA-TH-02-451, CERN-TH-2002-352, Dec 2002. 62pp.
    Published in Phys.Rev.D67:063514,2003.
    e-Print: hep-ph/0212112

    The Pre - big bang scenario in string cosmology. 232 cites !!!!
    M. Gasperini (Bari U. & INFN, Bari) , G. Veneziano (CERN) . BA-TH-02-437, CERN-TH-2002-104, Jul 2002. 251pp.
    Published in Phys.Rept.373:1-212,2003.
    e-Print: hep-th/0207130

    There we go! It looks like Pre-bang String Cosmology was big in the era 1992-2002 and then didn't go anywhere. I don't see any new authors coming in. I may be wrong, so I will keep checking a bit more, but I don't see a wave of grad students and postdocs following up on Veneziano and Gasperini work. Indeed Veneziano himself seems to have gotten away from Pre-bang---his research is in other directions.

    Rudy Vaas is editing a book called Beyond the Big Bang and he invited Veneziano and Gasperini to contribute an essay on stringy Pre-bang.
    That book will feature a whole lineup---Bojowald Ashtekar etc etc. The book will give a good perspective on the whole field of QC, I think. One will see where different approaches stand and which the currently active ones are. The Veneziano chapter for Rudy Vaas book is the 2007 paper I listed above that has 2 cites.
    "Beyond the Big Bang", ed. by Ruediger Vaas (Frontier Collection Series, Springer-Verlag, Heidelberg, 2007).
     
    Last edited: Jul 30, 2007
  18. Jul 31, 2007 #17

    marcus

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    I'm happy if anybody wants to suggest more names of prominent quantum cosmologists. Standard cosmology is models based on the Friedmann equations like the LambdaCDM and what I mean by QC is quantized versions of the basic cosmology equations, usually with removal of singularities and often leading to alternative explanation of inflation, pre-big-bang stuff etc.

    What I'm looking for is people who are currently ACTIVE, so they have a lot of recent papers specificially in QC, and their QC output since 1999 is HIGHLY CITED.
    Earlier I used a cutoff of 50+ cites because I didnt want to have to do a lot of adding up. But some people are newcomers and their papers are mostly 2005 and 2006 so they havent had time to get a lot of cites, so I will make the cutoff 35+.

    As a benchmark, as of 31 July, Bojowald has 23 papers with 35+ cites and a total of 1550 cites on just those papers. He has published many more papers of course but I am focusing on just the highly cited ones. I'm including papers about removing the black hole singularity by quantizing because it roughly parallels removing the big bang singularity, similar equations get quantized.

    Bojowald (23) 1550
    Ashtekar (6) 488
    Singh (6) 271
    Reuter (5) 267
    Veneziano (3) 369

    The above counts are all as of 31 July.

    Veneziano is stretching some because his work is not very recent. The 3 papers with 35+ cites dated after 1999 were all fairly old: 2000, 2002, and 2003. In this case I've included someone who does not seem currently active in cosmology.

    I'll try to get some figures for others.
    To get Singh's papers from Spires I used two commands
    find a Singh, Parampreet AND aff Penn State U.
    find a Singh, Parampreet AND aff IUCAA, Pune

    For Reuter, I used
    FIND A REUTER, MARTIN AND AFF MAINZ U., INST. PHYS.
    and found 10 with 35+ cites, of which half were explicitly about cosmology or black hole topics
    so I added up the cites for those five.
     
    Last edited: Aug 1, 2007
  19. Aug 29, 2007 #18

    marcus

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    I've redone the list focussing on RECENT quantum cosmology work, that is in the past 5 years---publication date >2002

    to save trouble only papers with 35+ cites are tallied. Here are the total number of cites
    as of 29 August 2007

    Bojowald 583
    Singh 394
    Ashtekar 309
    Steinhardt 257
    Reuter 80
    Veneziano 36

    To clarify, Bojowald had 11 recent papers with 35+ cites and their counts totaled 583.
    Veneziano had 1 recent paper with 35+ cites, one published in 2003 with 36.

    Ashtekar is a major figure in quantum gravity and very highly cited, but his research is not focused on cosmology. Bojowald and Singh research is specialized in quantum cosmology (and the related field of black holes). This list does not show Ashtekar's real stature because we are restricting the tally to QC, a specialized subfield of quantum gravity.

    Because there are several physicists named Martin Reuter I used the SPIRES search term:
    find a Reuter, Martin AND aff Mainz U., Inst. Phys. AND date > 2002
    This means find author Martin Reuter with affiliation to Mainz University Physics Institute
    To get the papers by Parampreet Singh I used
    find a Singh, Parampreet AND aff Penn State U. AND date > 2002
    find a Singh, Parampreet AND aff IUCAA, Pune AND date > 2002

    Martin Reuter is included as a "dark horse" in this list because his quantum cosmology has attracted wide interest and become widely known just in the past year or two. I expect his cites to catch up with the others, reflecting this.
    G. Veneziano is listed for comparison, although there is not much recent work.

    Readers are invited to suggest other names representative of the recent (>2002) quantum cosmology mainstream.
    The main way we have of detecting what is mainstream work is to tally up citations in the professional literature. If you would like to check, the main database is SPIRES at Stanford-SLAC:
    http://www.slac.stanford.edu/spires/
     
    Last edited: Aug 29, 2007
  20. Sep 17, 2007 #19

    marcus

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    I decided to update as of 16 September. Bojowald's line of LQC research is active with new researchers getting in, so his total grew by 70 cites in less than 3 weeks----29 august to 16 september. Same 11 papers but just more cites. Veneziano tally stayed the same (not much current work in his stringy pre-big bang scenario) however Steinhardt showed an impressive gain.

    Bojowald 652
    Singh 403
    Ashtekar 320
    Steinhardt 302
    Reuter 80
    Veneziano 36
     
    Last edited: Sep 17, 2007
  21. Sep 17, 2007 #20

    hellfire

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    Does Steinhard really do research on quantum cosmology, or does he work on finding a classical alternative to inflation?
     
    Last edited: Sep 17, 2007
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