Who the top quantum cosmology researchers are

[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.