2007/09/30 by James M. Cline, Andrew R. Frey, G. P. Holder +1 · 2 citations
Physics and Astronomy · #Advanced Thermodynamics and Statistical Mechanics #Cosmology and Gravitation Theories #Galaxies: Formation, Evolution, Phenomena #astro-ph #hep-ph #hep-th
paper · pdf · doi:10.1103/physrevd.77.063520
published as Phys.Rev.D77:063520,2008 · RevTeX4, 13pp, 10 figures; v2. clarified introduction, added refs
arxiv created 2007/11/03 · openalex publication_date 2008/03/19 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The causal entropic principle has been proposed as an alternative to the anthropic principle for understanding the magnitude of the cosmological constant. In this approach, the probability to create observers is assumed to be proportional to the entropy production \ensuremathΔS in a maximal causally connected region---the causal diamond. We improve on the original treatment by better quantifying the entropy production due to stars, using an analytic model for the star formation history which accurately accounts for changes in cosmological parameters. We calculate the dependence of \ensuremathΔS on the density contrast Q=\ensuremathδ\ensuremathρ/\ensuremathρ, and find that our universe is much closer to the most probable value of Q than in the usual anthropic approach and that probabilities are relatively weakly dependent on this amplitude. In addition, we make first estimates of the dependence of \ensuremathΔS on the baryon fraction and overall matter abundance. Finally, we also explore the possibility that decays of dark matter, suggested by various observed gamma ray excesses, might produce a comparable amount of entropy to stars.