Dark energy equation of state and anthropic selection

TL;DR

This paper investigates how anthropic selection might influence the properties of dark energy modeled by a scalar field, predicting either a nearly constant dark energy density or a universe that re-collapses, with observable consequences.

Contribution

It introduces models where anthropic effects determine the dark energy potential's slope, affecting the universe's fate and observable properties.

Findings

Most probable slope values are very small, implying a nearly constant dark energy density.

Some models predict a universe that re-collapses on a timescale comparable to the Sun's lifetime.

The effective equation of state may vary with redshift, offering testable predictions.

Abstract

We explore the possibility that the dark energy is due to a potential of a scalar field and that the magnitude and the slope of this potential in our part of the universe are largely determined by anthropic selection effects. We find that, in some models, the most probable values of the slope are very small, implying that the dark energy density stays constant to very high accuracy throughout cosmological evolution. In other models, however, the most probable values of the slope are such that the slow roll condition is only marginally satisfied, leading to a re-collapse of the local universe on a time-scale comparable to the lifetime of the sun. In the latter case, the effective equation of state varies appreciably with the redshift, leading to a number of testable predictions.