Born Again Universe

TL;DR

This paper introduces nonsingular bouncing cosmologies using vorticity in extra dimensions, which avoid singularities and could address the cosmological constant problem and support wormholes.

Contribution

It proposes a novel mechanism for nonsingular bounces via vorticity in compact extra dimensions, utilizing stable NEC-violating sources like Casimir energy.

Findings

Constructs a class of nonsingular bouncing cosmologies.

Demonstrates the use of vorticity to prevent geodesic focusing.

Suggests potential applications to the cosmological constant problem and wormholes.

Abstract

We present a class of nonsingular, bouncing cosmologies that evade singularity theorems through the use of vorticity in compact extra dimensions. The vorticity combats the focusing of geodesics during the contracting phase. The construction requires fluids that violate the null energy condition (NEC) in the compact dimensions, where they can be provided by known stable NEC violating sources such as Casimir energy. The four dimensional effective theory contains an NEC violating fluid of Kaluza-Klein excitations of the higher dimensional metric. These spacetime metrics could potentially allow dynamical relaxation to solve the cosmological constant problem. These ideas can also be used to support traversable Lorentzian wormholes.