From Big Bang to Big Crunch and Beyond

TL;DR

This paper explores a conformal field theory model describing a cosmological universe with big bang and big crunch singularities, connected through a series of spacetime regions, and discusses potential holographic interpretations.

Contribution

It introduces a quotient conformal field theory modeling a universe with sequential big bang and crunch singularities linked by non-compact regions, proposing a holographic perspective.

Findings

Model captures a universe with cyclic big bang and crunch phases.

Connects multiple Nappi-Witten spacetimes through singularities.

Suggests a holographic interpretation based on boundary observables.

Abstract

We study a quotient Conformal Field Theory, which describes a 3+1 dimensional cosmological spacetime. Part of this spacetime is the Nappi-Witten (NW) universe, which starts at a ``big bang'' singularity, expands and then contracts to a ``big crunch'' singularity at a finite time. The gauged WZW model contains a number of copies of the NW spacetime, with each copy connected to the preceeding one and to the next one at the respective big bang/big crunch singularities. The sequence of NW spacetimes is further connected at the singularities to a series of non-compact static regions with closed timelike curves. These regions contain boundaries, on which the observables of the theory live. This suggests a holographic interpretation of the physics.