Entropy of Contracting Universe in Cyclic Cosmology
Abstract
Following up a recent proposal^{1} for a cyclic model based on phantom dark energy, we examine the content of the contracting universe (cu) and its entropy S_{cu}. We find that beyond dark energy, the universe contains on average zero or an unlikely single photon which if present immediately after turnaround would have infinitesimal energy that blue shifts eventually to produce e^{+}e^{} pairs. These statements are independent of the equation of state ω = p/ρ of dark energy provided ω < 1. Thus S_{cu} = 0 and if observations confirm ω < 1, the entropy problem is solved. We discuss the absence of a theoretical lower bound on ϕ = ω+1, then describe an anthropic fine tuning argument that renders unlikely extremely small ϕ. The present bound ϕ ≲ 0.1 already implies a time until turnaround of (t_{T}  t_{0}) ≳ 100 Gy.
 Publication:

Modern Physics Letters A
 Pub Date:
 2008
 DOI:
 10.1142/S0217732308026170
 arXiv:
 arXiv:hepth/0703162
 Bibcode:
 2008MPLA...23...33B
 Keywords:

 High Energy Physics  Theory
 EPrint:
 5 pages latex