Who the top quantum cosmology researchers are

[marcus]

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.

 

[marcus]

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/find/hep/www?rawcmd=FIND+A+BOJOWALD+AND+TOPCITE+50%2B&FORMAT=www&SEQUENCE=citecount%28d%29

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.

 

[marcus]

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

 

[Chronos]

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.

 

[marcus]

Permit me to introduce John Barrow, if i may, marcus...

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) then it doesn't 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?

 

[marcus]

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/find/hep/www?rawcmd=FIND+A+ASHTEKAR+AND+TOPCITE+50%2B+AND+DATE+%3E+1999&FORMAT=www&SEQUENCE=citecount%28d%29

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.

 

[marcus]

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

 

[marcus]

Another person to consider would be Parampreet Singh
http://www.slac.stanford.edu/spires/find/hep/www?rawcmd=FIND+A+SINGH+AND+K+QUANTUM+COSMOLOGY+AND+DATE+%3E+1999&FORMAT=www&SEQUENCE=citecount%28d%29
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.

 

[marcus]

I just noticed this comment from another poster:

Perlmutter is still taking hits for the supernova study . . . which is fair. Bojowald is not taking hits because hardly anyone attempts [or cares to invest the effort] to understand his work. I'm not opposed to a 'bounce', but, does it make useful predictions?

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.

 

[marcus]

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).

 

[Steve1]

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 !..

 

[marcus]

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 !..

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 doesn't draw so much on the earlier. Hawking advocated something called "Euclidean path integral" in the 1980s and he still touts it publically but he couldn't get other people interested and it went out of style.

there are some more speculative string-inspired ideas but they don't 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 doesn't 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.

 

[marcus]

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

 

[Chronos]

I'm still looking for the next level arising from quantum information theory. Just a hunch.

 

[hellfire]

there are some more speculative string-inspired ideas but they don't 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 doesn't seem to spread.

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 http://www.slac.stanford.edu/spires/find/hep/www?rawcmd=FIND+EPRINT+hep-th%2F9211021&FORMAT=www&SEQUENCE= with 500+ cites or http://www.citebase.org/abstract?id=oai%3AarXiv.org%3Ahep-th%2F9507017 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.

 

[marcus]

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?

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 http://www.slac.stanford.edu/spires/find/hep/www?rawcmd=FIND+EPRINT+hep-th%2F9211021&FORMAT=www&SEQUENCE= with 500+ cites or http://www.citebase.org/abstract?id=oai%3AarXiv.org%3Ahep-th%2F9507017 with 100+ cites. Moreover, pre-big-bang cosmology has provided very concrete testable predictions such as the spectrum of the background of gravitational waves...

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 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).

 

[marcus]

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 haven't 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.

 

[marcus]

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/

 

[marcus]

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.

...
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/

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

 

[hellfire]

Does Steinhard really do research on quantum cosmology, or does he work on finding a classical alternative to inflation?

 

[marcus]

Does Steinhard really do research on quantum cosmology, or does he work on finding a classical alternative to inflation?

Personally I don't consider Steinhardt's "clashing branes" explanation of the bigbang to be quantum cosmology, as I usually think of it.

But the Steinhardt work is STRINGY and it does provide one kind of BEFORE the big bang story. So some people might think of it as the principle string-inspired rival to Bojowald/Ashtekar LQC and they might think it was unfair to leave Steinhardt out.

I'd like to be fairly inclusive. So even though technically Steinhardt "ekpyrotic" or cyclically crashing branes scenario doesn't look like a sensible quantum cosmology to me, I've included him. If you think this is a bad idea let me know, I'll think about dropping him.

the thing I like about Steinhardt is he did some work a while ago that found inflation was incompatible with the complex arrangement of stringy extra dimensions. As he said recently in comment on paper by Tegmark Kachru et al, you either have to throw out string theory or throw out inflation. So Steinhardt set to work to find a way of getting some of the EFFECTS of inflation without actually having inflation----a way to resolve the same puzzles that inflation resolves but without all that exponential expansion. And he and Turok dreamed up these colliding branes that bump each other over and over again.
To me that says the guy is serious---he doesn't just sweep contradictions under the rug and ignore them---and he was making a determined effort to avoid the logical necessity of abandoning string philosophy. I admire his integrity and imagination even though his scenario seems a bit farfetched to me.

I'll get a link to the Tegmark Kachru work

http://arxiv.org/abs/0709.0002
Searching for Inflation in Simple String Theory Models: An Astrophysical Perspective
Mark P. Hertzberg (MIT), Max Tegmark (MIT), Shamit Kachru (Stanford), Jessie Shelton (Rutgers), Onur Ozcan (MIT)
24 pages, 5 figs
(Submitted on 3 Sep 2007 (v1), last revised 3 Sep 2007 (this version, v2))

"...We analyze three explicit string models from the recent literature, each containing an infinite number of "vacuum" solutions. Our numerical investigation of some natural candidate inflatons, the so-called "moduli fields", fails to find inflation. We also find in the simplest models that, after suitable field redefinitions, vast numbers of these vacua differ only in an overall constant multiplying the effective inflaton potential, a difference which affects neither the potential's shape nor its ability to support slow-roll inflation. This illustrates that even having an infinite number of vacua does not guarantee having inflating ones. This may be an artifact of the simplicity of the models that we study. Instead, more complicated string theory models appear to be required, suggesting that explicitly identifying the inflating subset of the string landscape will be challenging." http://space.newscientist.com/article/dn12628-can-string-theory-accommodate-inflation.html
Can string theory accommodate inflation?

Steinhardt is quoted in this last article. He says NO string cannot accommodate inflation, and this is what he found out some time ago which he thinks these other guys are just confirming. And I guess that was basically why he tried so hard to find an alternative mechanism to inflation, so you could chuck out inflation and keep string---at least in his subjective view of things.

 

[marcus]

I found a better way to do the search in one case
for Parampreet Singh, it works best to use the "EA" command instead of the simple "A"
FIND EA SINGH, PARAMPREET AND DATE>2002
and the current total is 405.
FIND A BOJOWALD AND DATE>2002 gave 658

 

[marcus]

This list focuses on quantum cosmology (and related quantum BH) work published in the last 5 years---currently publication date >2002
To save trouble only papers with 35+ cites are tallied. Here are the total number of cites
as of 22 September 2007. I've included the Spires search commands in case anyone else would like to update the list.
FIND A... means "find author...".

Bojowald 660
FIND A BOJOWALD AND DATE > 2002
Singh 408
FIND EA SINGH, PARAMPREET AND DATE>2002
Ashtekar 327
FIND A ASHTEKAR AND DATE > 2002
Steinhardt 298
FIND A STEINHARDT AND DATE > 2002
Reuter 80
FIND A REUTER, MARTIN AND AFF MAINZ U., INST. PHYS. AND DATE > 2002
Veneziano 37
FIND A VENEZIANO AND DATE > 2002

http://www.slac.stanford.edu/spires/

 

[marcus]

The last time i updated this list of leading QC researchers was over two months ago, so I'll refresh the numbers. If you have someone else to suggest----active in quantum cosmology and quantum black hole research during the past 5 years---whom we should watch, please let me know

This list focuses on quantum cosmology (and related quantum BH) papers published in the last 5 years---currently publication date >2002
To save trouble only papers with 35+ cites are tallied. Here are the total number of cites
as of 30 November 2007.

Bojowald 716
Singh 475
Ashtekar 394
Steinhardt 344
Reuter 82
Veneziano 38

I've included the Spires search commands in case anyone else would like to update the list.
FIND A... means "find author...".

FIND A BOJOWALD AND DATE > 2002
FIND EA SINGH, PARAMPREET AND DATE>2002
FIND A ASHTEKAR AND DATE > 2002
FIND A STEINHARDT AND DATE > 2002
FIND A REUTER, MARTIN AND AFF MAINZ U., INST. PHYS. AND DATE > 2002
FIND A VENEZIANO AND DATE > 2002

http://www.slac.stanford.edu/spires/

It is noticeable that Bojowald, Singh, Ashtekar each picked up 55-70 cites in the past 2 months, suggesting that their work is hot. Steinhardt picked up 46, which is is almost at that level. Quantum cosmology is a small field with only a few researchers working in it, so these numbers indicate considerable activity relative to the size of the community.

 

[marcus]

... If you have someone else to suggest----active in quantum cosmology and quantum black hole research during the past 5 years---whom we should watch, please let me know. This list focuses on quantum cosmology (and related quantum BH) papers published in the last 5 years...publication date >2002
To save trouble only papers with 35+ cites are tallied.

Here are the total number of cites
as of 16 December 2007.

Bojowald 732
Singh 475
Ashtekar 406
Steinhardt 347
Reuter 86
Hawking 70
Veneziano 39

Source:
http://www.slac.stanford.edu/spires/
Search terms:
FIND A BOJOWALD AND DATE > 2002
FIND EA SINGH, PARAMPREET AND DATE>2002
FIND A ASHTEKAR AND DATE > 2002
FIND A STEINHARDT AND DATE > 2002
FIND A REUTER, MARTIN AND AFF MAINZ U., INST. PHYS. AND DATE > 2002
FIND A HAWKING AND DATE > 2002
FIND A VENEZIANO AND DATE > 2002

 

[marcus]

Here are the citation totals as of 28 December 2007. Only papers published since 2002 which have received 35+ cites are tallied.

Bojowald 737
Singh 477
Ashtekar 409
Steinhardt 351
Reuter 86
Hawking 71
Veneziano 39

Source:
http://www.slac.stanford.edu/spires/

 

[marcus]

... If you have someone else to suggest----active in quantum cosmology and quantum black hole research during the past 5 years---whom we should watch, please let me know. This list focuses on quantum cosmology (and related quantum BH) papers published in the last 5 years...publication date >2002
To save trouble only papers with 35+ cites are tallied.

Here are the total number of cites
as of 16 December 2007.

Bojowald 732
Singh 475
Ashtekar 406
Steinhardt 347
Reuter 86
Hawking 70
Veneziano 39

Source:
http://www.slac.stanford.edu/spires/
Search terms:
FIND A BOJOWALD AND DATE > 2002
FIND EA SINGH, PARAMPREET AND DATE>2002
FIND A ASHTEKAR AND DATE > 2002
FIND A STEINHARDT AND DATE > 2002
FIND A REUTER, MARTIN AND AFF MAINZ U., INST. PHYS. AND DATE > 2002
FIND A HAWKING AND DATE > 2002
FIND A VENEZIANO AND DATE > 2002

I see that Renate Loll's name needs to be added to the list. The Spires search term is
FIND A LOLL AND DATE > 2002

In another thread, the question came up as to which scientists study conditions just before the big bang, and the possible causes of the start of expansion. This is mainly the subject of quantum cosmology and we should be able to keep track of who the leading quantum cosmologists are----citations to recent work (published in the last 5 years.)

It is time to update, and add some new names if anyone has some to suggest. This is now
as of 10 February 2008.

Bojowald 743
Singh 489
Ashtekar 423
Steinhardt 391
Loll 145
Reuter 88
Hawking 75
Veneziano 40

 

[marcus]

Here are the total number of cites
as of 16 December 2007.

Bojowald 732
Singh 475
Ashtekar 406
Steinhardt 347
Reuter 86
Hawking 70
Veneziano 39

Source:
http://www.slac.stanford.edu/spires/
Search terms:
FIND A BOJOWALD AND DATE > 2002
FIND EA SINGH, PARAMPREET AND DATE>2002
FIND A ASHTEKAR AND DATE > 2002
FIND A STEINHARDT AND DATE > 2002
FIND A REUTER, MARTIN AND AFF MAINZ U., INST. PHYS. AND DATE > 2002
FIND A HAWKING AND DATE > 2002
FIND A VENEZIANO AND DATE > 2002

This needs to be updated, and the list should be added to. I'm trying to devise an easier way to keep track of who the leading people are in quantum cosmology.

Here is another approach
http://www.slac.stanford.edu/spires/find/hep/www?rawcmd=FIND+dK+QUANTUM+COSMOLOGY+AND+DATE+%3E+2003&FORMAT=www&SEQUENCE=citecount%28d%29

This takes hardly any time. I just do a search of the Spires database for DESY keyword QUANTUM COSMOLOGY and date > 2003, and ask for the papers to be ranked by citation count, so the most important papers are listed first.

 

[Haelfix]

Does inflation count? What about cosmic strings/topological defects, and any number of phenomenological objects that could arise in principle from quantum cosmology.

People like Linde and some of the other big astrophysics names double or triple the citation count of anybody on that list

 

[marcus]

Does inflation count? What about cosmic strings/topological defects, and any number of phenomenological objects that could arise in principle from quantum cosmology.
...

Hi Haelfix, thanks for joining the discussion!

You probably noticed that the DESY librarians who apply the Spires keywords do not consider Linde's papers to be quantum cosmology. Nor do they include cosmic strings.

Why should this be? Apparently it puzzles you. I will try to help you understand.

I think (and this is only my guess) that it is because Linde's papers about inflation are based on CLASSICAL geometry. The universe does not have a quantized geometry in all that usual inflation work. The size or scale factor is not represented by a wave function, for instance.

The same is true with cosmic strings. The underlying geometric model is classical, not quantum.

So none of that stuff you mention is considered to be quantum cosmology.

 

[marcus]

...
http://www.slac.stanford.edu/spires/find/hep/www?rawcmd=FIND+dK+QUANTUM+COSMOLOGY+AND+DATE+%3E+2003&FORMAT=www&SEQUENCE=citecount%28d%29

This takes hardly any time. I just do a search of the Spires database for DESY keyword QUANTUM COSMOLOGY and date > 2003, and ask for the papers to be ranked by citation count, so the most important papers are listed first.

Some cosmology work, like inflation scenarios, uses classical cosmology. They just postulate an exotic matter field that has negative pressure, but they plug that into the classical 1923 Friedmann model!

Of course the imagined exotic matter field, like any matter field, would be a quantum object. But this does not mean that the 1923 cosmological model they plug it into is quantum!

So let's try to understand better what is considered to be quantum cosmology. Stanford SLAC has this wonderful Spires database that everybody seems to use and the papers are tagged by a bunch of librarians in Germany, at the DESY.

They tag papers by string theorists as quantum cosmology when they actually are quantum cosmology. Or so it seems to me. For example they tagged a paper by Cumrun Vafa, and Hirosi Ooguri, and Erik Verlinde as QC. Let's check and see what they tag.

And by the way the Spires people are not necessarily right! I think they omit Renate Loll who obviously does QC because she models quantum universes in the computer! It is clearly a QC path integral. The universe is being modeled with a totally quantum geometry. But so far DESY overlooks that work. Nevertheless, let's try to see how the Spires librarians think. I will copy their list of the most-cited recent QC papers.

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: http://arxiv.org/abs/gr-qc/0404018
295

2) 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: http://arxiv.org/abs/gr-qc/0601085
103

3) Hartle-Hawking wave-function for flux compactifications.
Hirosi Ooguri (Caltech) , Cumrun Vafa (Harvard U., Phys. Dept.) , Erik P. Verlinde (Amsterdam U.) . CALT-68-2543, HUTP-05-A005, ITFA-2005-05, Feb 2005. 37pp.
Published in Lett.Math.Phys.74:311-342,2005.
e-Print: http://arxiv.org/abs/hep-th/0502211
89

4) 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: http://arxiv.org/abs/gr-qc/0602086
74

5) 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: http://arxiv.org/abs/gr-qc/0607039
71

6) 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: http://arxiv.org/abs/gr-qc/0604013
65

7) 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: http://arxiv.org/abs/gr-qc/0402053
58

8) Baby universes in string theory.
Robbert Dijkgraaf (Amsterdam U.) , Rajesh Gopakumar (Harish-Chandra Res. Inst.) , Hirosi Ooguri (Caltech) , Cumrun Vafa (Harvard U., Phys. Dept.) . CALT-68-2557, HUTP-05-A019, ITFA-2005-14, Apr 2005. 39pp.
Published in Phys.Rev.D73:066002,2006.
e-Print: http://arxiv.org/abs/hep-th/0504221
53

9) Oscillatory universes in loop quantum cosmology and initial conditions for inflation.
James E. Lidsey, David J. Mulryne, N.J. Nunes, Reza Tavakol (Queen Mary, U. of London, Math. Sci.) . Jun 2004. 6pp.
Published in Phys.Rev.D70:063521,2004.
e-Print: http://arxiv.org/abs/gr-qc/0406042
52

10) On the Hamiltonian constraint of loop quantum cosmology.
Kevin Vandersloot (Penn State U.) . Feb 2005. 28pp.
Published in Phys.Rev.D71:103506,2005.
e-Print: http://arxiv.org/abs/gr-qc/0502082
42

11) Genericity of big bounce in isotropic loop quantum cosmology.
Ghanashyam Date, Golam Mortuza Hossain (IMSc, Chennai) . IMSC-2004-07-29, Jul 2004. 4pp.
Published in Phys.Rev.Lett.94:011302,2005.
e-Print: gr-qc/0407074
40

12) Creation of a compact topologically nontrivial inflationary universe.
Andrei Linde (Stanford U., Phys. Dept.) . Aug 2004. 8pp.
Published in JCAP 0410:004,2004.
e-Print: http://arxiv.org/abs/hep-th/0408164
40

I have written the currenct citation number in bold. I see that Linde has a paper that the database DOES treat as quantum cosmology! I will have to take a look and see in what sense it qualifies. this is interesting. Maybe we should add Linde to the list.

 

[Haelfix]

Some of the LQG 'inspired' models are semiclassical treatments, so its not clear what the criteria actually is, it seems to me rather arbitrary.

 

[marcus]

Some of the LQG 'inspired' models are semiclassical treatments,
...

Could you give me an example? I mean an example where the DESY librarians put a paper into the database with keyword "quantum cosmology" and it wasn't really quantum cosmology in your sense.

What do you mean by semiclassical in this context? I'd like to understand better what you are trying to say.

 

[Haelfix]

I don't really know what the DESY librarians mean when they say a paper is QC. WHat they most certainly do not preclude (since some are listed), are semiclassical treatments like inflation and some of say Bojowalds 'effective bounce' papers.

Its a very fine line ultimately akin to the difference between theory and phenomenology in particle physics since it seems (if I had to guess) that its just a question of how much pure quantum gravity theory perse is involved in the paper relative to the amount of text exploring the consequences for the classical cosmological limits (+ modifications).

 

[marcus]

As I said before, I would appreciate it if you would give me a link to a particular paper which Spires database classifies as quantum cosmology, which you do not think is quantum cosmology in your sense of the word.

The reason is, I'm curious about what your idea of quantum cosmology is, and I need to see it applied at the level of a specific paper or two.