Predictions of the causal entropic principle for environmental conditions of the universe

TL;DR

This paper refines the causal entropic principle to better predict the universe's environmental conditions by modeling entropy production from stars, dark matter decay, and cosmological parameters, showing closer alignment with observed universe parameters.

Contribution

It improves the quantification of entropy production in the causal entropic principle, incorporating detailed star formation models and exploring dark matter decay effects.

Findings

Universe's Q value is closer to the most probable than in anthropic models.

Entropy production weakly depends on amplitude Q.

Dark matter decay could produce comparable entropy to stars.

Abstract

The causal entropic principle has been proposed as a superior 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 \Delta S 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 \Delta S on the density contrast Q=\delta\rho/\rho, 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 \Delta S 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.