Relativity and Cosmology


Entropy Growth in the Early Universe, and the Search for Determining if Gravity is Classical or Quantum , Part III (Is Gravity a Classical or Quantum Phenomenon at Its Genesis 13.7 Billion Years Ago?)

Authors: Andrew Beckwith

In the 12th Marcel Grossmann Meeting, July 9th, 2009, the author raised the issue of whether early graviton production could affect non-Gaussian contributions to DM density profiles. Non gaussianity of evolving cosmological states is akin to asking if there is a way to get quantum contributions due to squeezed initial vacuum states which act highly non classscially. If particle counting algorithms in graviton production is important as for entropy, and if entropy perturbations affects the density profile of dark matter clumping prifiles, then there is room to ask to what degree initial perturbations affecting structure formation are due to classical/ non linear processes, or more quantum theoretic states. If squeezing of the initial vacuum states is essential in the relic conditions, then quantization is unavoidable. If squeezing is not essential, then coherent initial vacuum states may contribute in semi classical ways to GW production . The end result of this stated inquiry may be answering if or not gravity in the onset of inflation is a quantized field. Or if a highly non linear set of complex initial conditions for gravity can be stated using purely classical models, as T'Hooft, Corda, and others believe. Note, also that Bojowald as of 2008 has left the degree of squeezing of initial vacuum states in the region of space as an open problem. In Bojowald's model of a cosmological bounce, the degree of squeezing is a measure of what strength the "bounce" from an initial configuration of the universe takes, and how strongly quantum effects contribute to the evolution of the LQG cosmos, after inflation commences. Similar questions are being raised as to the necessity of squeezing of initial vacuum states and if or not coherency of initial states is initially largely achievable, before the rapid expansion of the universe commences. Finally, and not least is a series of questions as to what conditions which would either require high or low frequencies as to relic signals from the big bang. As it is, large spatial dimensions which could induce far lower initial frequencies for relic signals are popular in many string theory models. The author views this assumption as of debatable validity, as well as the assumption made by Arkani Hamid that largely does away with coherency of initial vacuum states and specifies highly quantum , low frequency generation of relic GW.

Comments: part III of a series of inter related articles in the process of finalization which discuss entropy in terms of the search for if or not gravity is a classical or quantum emergent "field" in relic conditions. 33 pages

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Submission history

[v1] 3 Sep 2009
[v2] 4 Sep 2009

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