Turnaround in Cyclic Cosmology

TL;DR

This paper proposes a cyclic cosmology model where dark energy causes a universe turnaround before a Big Rip, reducing entropy drastically and spawning multiple universes, thus addressing thermodynamic concerns.

Contribution

It introduces a novel cyclic cosmology framework with dark energy-driven turnaround that decreases entropy and generates multiple universes, reconciling cyclic models with thermodynamics.

Findings

Entropy decreases almost to zero at turnaround

Multiple universes are spawned at turnaround

Entropy increases during expansion and contraction phases

Abstract

It is speculated how 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 leads to a turnaround at a time, extremely shortly before the would-be Big Rip, at which both volume and entropy of our universe decrease by a gigantic factor, while very many independent similarly small contracting universes are spawned. The entropy of our universe decreases almost to zero at turnaround but increases for the remainder of the cycle by a vanishingly small amount during contraction, empty of matter, then by a large factor during inflationary expansion.