Amplification of Curvature Perturbations in Cyclic Cosmology

TL;DR

This paper demonstrates analytically and numerically that in cyclic cosmology models with nonsingular bounces, curvature perturbations are amplified over cycles, potentially leading to a multiverse scenario with localized cycles.

Contribution

It provides a detailed analysis of curvature perturbation amplification in cyclic models, highlighting the potential for multiverse emergence due to increasing cycle amplitudes.

Findings

Curvature perturbations are amplified across cycles.

The power spectrum becomes reddened over time.

Homogeneity of the universe may be destroyed after multiple cycles.

Abstract

We analytically and numerically show that through the cycles with nonsingular bounce the amplitude of curvature perturbation on large scale will be amplified and the power spectrum will be redden. In some sense, this amplification will eventually destroy the homogeneity of background, which will lead to the ultimate end of cycles of global universe. We argue that for the model with increasing cycles, it might be possible that a fissiparous multiverse will emerge after one or several cycles, in which the cycles will continue only at corresponding local regions.