Deflation at Turnaround for Oscillatory Cosmology

TL;DR

This paper proposes a cyclic cosmology model where dark energy induces a turnaround, allowing entropy to decrease during contraction, thus addressing thermodynamic consistency and the arrow of time in oscillatory universe scenarios.

Contribution

It introduces a model where dark energy facilitates a finite-time turnaround with entropy reduction, reconciling cyclic cosmology with thermodynamics and time's arrow.

Findings

Dark energy causes a finite-time turnaround in cyclic cosmology.

Entropy decreases during contraction, balancing entropy increase during expansion.

Thermodynamic consistency requires reversal of the arrow of time during contraction.

Abstract

It is suggested that dark energy in a brane world can help reconcile an infinitely cyclic cosmology with the second law of thermodynamics. A cyclic cosmology is described, in which dark energy with constant equation of state leads to a turnaround at finite future time, when entropy is decreased by a huge factor equal to the inverse of its enhancement during the initial inflation. Thermodynamic consistency of cyclicity requires the arrow of time to reverse during contraction. Entropy reduction in the contracting phase is infinitesimally smaller than entropy increase during expansion.