Exploring Loop Quantum Cosmology with the Planck Satellite

[skydivephil]

Will the results from the PLanck satellite shed any light on Loop Quantum Cosmology or any other form of matter bounce?

 

[marcus]

If you don't want to rely on the words of non-specialists, look up the work of Barrau and others (experts on this question.)

You should learn how to use arxiv.org if you don't already.

Google "arxiv search" and you get
http://arxiv.org/find

Put in the name "Barrau" and you get the papers of Aurelien Barrau
http://arxiv.org/find/all/1/au:+Barrau_A/0/1/0/all/0/1

==quote sample==
3. arXiv:1003.4660 [pdf, ps, other]
Inflation in loop quantum cosmology: Dynamics and spectrum of gravitational waves
Jakub Mielczarek, Thomas Cailleteau, Julien Grain, Aurelien Barrau
Comments: 11 pages, 14 figures. Matches version published in Phys. Rev. D
Journal-ref: Phys.Rev.D81:104049,2010
Subjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Extragalactic Astrophysics (astro-ph.CO); High Energy Physics - Theory (hep-th)
4. arXiv:1001.2973 [pdf, ps, other]
Very high energy gamma-rays and the Hubble parameter
A. Gorecki, A. Barrau, J. Grain, E. Memola
Comments: Proc. of the 12th Marcel Grossmann meeting on general relativity. 3 pages, 1 figure
Subjects: Cosmology and Extragalactic Astrophysics (astro-ph.CO); High Energy Astrophysical Phenomena (astro-ph.HE)
5. arXiv:0911.3745 [pdf, ps, other]
Loop quantum gravity and the CMB: toward pre-Big Bounce cosmology
Aurelien Barrau
Comments: Proceedings of the 12th Marcel Grossman Meeting on General Relativity. 3 pages, no figure
Subjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Extragalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Theory (hep-th)
6. arXiv:0910.2892 [pdf, ps, other]
Fully Loop-Quantum-Cosmology-corrected propagation of gravitational waves during slow-roll inflation
J. Grain, T. Cailleteau, A. Barrau, A. Gorecki
Comments: 9 pages, no figure, minor corrections
Journal-ref: Phys.Rev.D81:024040,2010
Subjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Extragalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Theory (hep-th)
7. arXiv:0902.4810 [pdf, ps, other]
Internal structure of a Maxwell-Gauss-Bonnet black hole
S. Alexeyev, A. Barrau, K.A. Rannu
Comments: 5 pages, 5 figures, published version with minor changes
Journal-ref: Phys.Rev.D79:067503,2009
Subjects: General Relativity and Quantum Cosmology (gr-qc)
8. arXiv:0902.3605 [pdf, ps, other]
Inverse volume corrections from loop quantum gravity and the primordial tensor power spectrum in slow-roll inflation
J. Grain, A. Barrau, A. Gorecki
Comments: 15 pages, 5 figures, published version with minor modifications, results unchanged
Journal-ref: Phys.Rev.D79:084015,2009
Subjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Extragalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Theory (hep-th)
9. arXiv:0902.0145 [pdf, ps, other]
Cosmological footprints of loop quantum gravity
J. Grain, A. Barrau
Comments: Accepted by Phys. Rev. Lett., 7 pages, 2 figures
Journal-ref: Phys.Rev.Lett.102:081301,2009
Subjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Extragalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Theory (hep-th); Quantum Physics (quant-ph)
==endquote==

EACH ONE OF THOSE PAPERS HAS A LINK TO THE ABSTRACT AND A LINK TO THE PDF
And each one of Barrau's co-authors is a link to the work by that co-author, so you can get a list of the work of Julien Grain, and of Jakub Mielczarek etc.

 

[marcus]

So you can read, if you want.
For each paper there is the abstract summary, and the introduction, and the conclusions paragraph at the end that generally gives an overview.

These people are interested in what can be learned from Planck data, when it becomes available, and they are interested in testing theories. So in these papers they are TALKING about the relevance of Planck data to LQG/LQC.

That is their job. They are not Loop specialists, they are phenomenologists, interested in testing any and all cosmological models, and also astrophysics stuff. I don't think they actually know what to expect from Planck data, or how relevant it will be to LQC. But you can see them making guarded qualified statements about what the "footprint" of LQC should be and how it might or might not show up.

As you may know, LQC has undergone radical changes since 2006 (a new dynamics) and even more since 2008 (spin foam cosmology, getting rid of simplifying assumptions of homogeneity and isotropy, merging with full LQG theory).

For the most recent advances in LQC, look up the papers of Rovelli with coauthor Vidotto
(also those of Ashtekar, Henderson, Wilson-Ewing).
There is a recent (October 2010) paper by Rovelli, Vidotto, Henderson, and Wilson-Ewing on spinfoam LQG cosmology.
This goes somewhat beyond what we used to think of as LQC a couple of years ago.
It has references to other papers so you can work back if you want:
http://arxiv.org/abs/1010.0502

 

[skydivephil]

Wow that's a lot to be getting on with, thanks.

 

[marcus]

Wow that's a lot to be getting on with, thanks.

But Phil! You don't have to even glance at any of it!
My feeling about this is that you have asked an extremely interesting question, that we should be following over the next 12 months. And that right now IMHO we don't know the answer. Even experts don't yet know what bearing Planck will have on LQG/LQC.

The only thing I know to do is to read (or skim) the brief summaries, and the conclusion sections, of the papers by phenomenologists like Barrau. (and Grain, Mielczarek etc.) And get a sense of it, how definite are they being, how reserved, what do they think?

I don't think there is a sure conclusive answer to the question yet. But it is something to watch.

I do know that two major leaders in LQG are Rovelli and Ashtekar---and before 2006 Ashtekar was doing comparatively little in cosmology, now it is his main focus. And before 2009 Rovelli was not doing LQC at all---now LQG application to cosmology is a major interest of his (several papers per year). People get to be leaders by knowing what to work on---it is a sign that Loop cosmo is ripe when it has drawn their attention away from the main theory. From the general to the critical application.

 

[Chalnoth]

Will the results from the PLanck satellite shed any light on Loop Quantum Cosmology or any other form of matter bounce?

The short answer is: probably not much. It will add further constraints to the available parameter space, but it isn't likely to be enough to really constrain inflation (which is where LQC comes into play).

 

[skydivephil]

But Phil! You don't have to even glance at any of it!
My feeling about this is that you have asked an extremely interesting question, that we should be following over the next 12 months. And that right now IMHO we don't know the answer. Even experts don't yet know what bearing Planck will have on LQG/LQC.

The only thing I know to do is to read (or skim) the brief summaries, and the conclusion sections, of the papers by phenomenologists like Barrau. (and Grain, Mielczarek etc.) And get a sense of it, how definite are they being, how reserved, what do they think?

I don't think there is a sure conclusive answer to the question yet. But it is something to watch.

I do know that two major leaders in LQG are Rovelli and Ashtekar---and before 2006 Ashtekar was doing comparatively little in cosmology, now it is his main focus. And before 2009 Rovelli was not doing LQC at all---now LQG application to cosmology is a major interest of his (several papers per year). People get to be leaders by knowing what to work on---it is a sign that Loop cosmo is ripe when it has drawn their attention away from the main
theory. From the general to the critical application.

As somone who is not a professional comsologist,Im a bit worried that any results from Planck might be ad hocly re interpreted as consistent with one framework or another. I doubt Id be any the wiser. What I think would be really exicting would be if there were any specific predictions of what we will find in the data Planck will provide. Or maybe even LISA if it ever gets funded (anyone know what the current situation is with that?)

 

[wolram]

http://www.esa.int/esaSC/SEM5TDWO4HD_index_0.html

Lisa launch date 2018, if all goes well.

Launch Scheduled for 2018, the mission is currently planned to launch from NASA’s Kennedy Space Centre in the USA on board an Atlas 531 rocket.