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New cosmic model parameters from South Pole Telescope

 
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Mar24-13, 12:38 PM   #35
 
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New cosmic model parameters from South Pole Telescope


Maybe I should mention that early universe observation (like Planck mission) is viewed as the main testing arena in other words a proving ground for Quantum Gravity.
This paper which came out a couple of days ago examples that.

http://arxiv.org/abs/1303.4989
Loop Quantum Gravity and the The Planck Regime of Cosmology
Abhay Ashtekar
(Submitted on 20 Mar 2013)
The very early universe provides the best arena we currently have to test quantum gravity theories. The success of the inflationary paradigm in accounting for the observed inhomogeneities in the cosmic microwave background already illustrates this point to a certain extent because the paradigm is based on quantum field theory on the curved cosmological space-times. However, this analysis excludes the Planck era because the background space-time satisfies Einstein's equations all the way back to the big bang singularity. Using techniques from loop quantum gravity, the paradigm has now been extended to a self-consistent theory from the Planck regime to the onset of inflation, covering some 11 orders of magnitude in curvature. In addition, for a narrow window of initial conditions, there are departures from the standard paradigm, with novel effects, such as a modification of the consistency relation involving the scalar and tensor power spectra and a new source for non-Gaussianities. Thus, the genesis of the large scale structure of the universe can be traced back to quantum gravity fluctuations in the Planck regime. This report provides a bird's eye view of these developments for the general relativity community.
23 pages, 4 figures. Plenary talk at the Conference: Relativity and Gravitation: 100 Years after Einstein in Prague. To appear in the Proceedings to be published by Edition Open Access. Summarizes results that appeared in journal articles [2-13]

According to Ashtekar, LQG can be used to model an era of expansion before inflation in which conditions might arise that affect how it plays out in novel and measurable ways. In papers leading up to this one synonyms like "pre-inflationary era" have been used in place of "Planck regime".
Mar24-13, 03:23 PM   #36
 
Quote by marcus View Post
Maybe I should mention that early universe observation (like Planck mission) is viewed as the main testing arena in other words a proving ground for Quantum Gravity.
This paper which came out a couple of days ago examples that.

http://arxiv.org/abs/1303.4989
Loop Quantum Gravity and the The Planck Regime of Cosmology
Abhay Ashtekar
(Submitted on 20 Mar 2013)
Interesting that he was one of the originators of LQG too.

http://en.wikipedia.org/wiki/Loop_qu...ravity#History

... In papers leading up to this one synonyms like "pre-inflationary era" have been used in place of "Planck regime".
I always assumed there had to be a gap since the horizon problem is supposedly solved by allowing inflation to expand a region which had reached thermodynamic equilibrium to larger than our horizon. That seems to imply a period before inflation started during which equilibrium could be achieved. "Planck regime" would then be a subset of "pre-inflationary era" with the former ending around 10^-43s and the latter starting around 10^-36s.

Thanks for bringing this up, LQG is something I hadn't look at before, it seems it's going to become more relevant as Planck is reaching the sensitivity where it might become testable.

From your previous message:

Note that the central values are, as usual, negative.
Yeah, by 0.08 sigma
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