Exact Evolution of Discrete Relativistic Cosmological Models

TL;DR

This paper investigates how inhomogeneities in discretized matter models affect the universe's evolution using exact relativistic methods, revealing diverse behaviors including possible large-scale acceleration without energy condition violations.

Contribution

It introduces a fully relativistic approach to model inhomogeneous cosmologies with discretized matter, enabling analysis of their entire evolution beyond previous limitations.

Findings

Some models develop anisotropic singularities

Others remain non-singular throughout history

Large-scale acceleration can occur without energy condition violations

Abstract

We study the effects of inhomogeneities on the evolution of the Universe, by considering a range of cosmological models with discretized matter content. This is done using exact and fully relativistic methods that exploit the symmetries in and about submanifolds of spacetimes that themselves possess no continuous global symmetries. These methods allow us to follow the evolution of our models throughout their entire history, far beyond what has previously been possible. We find that while some space-like curves collapse to anisotropic singularities in finite time, others remain non-singular forever. The resulting picture is of a cosmological spacetime in which some behaviour remains close to Friedmann-like, while other behaviours deviate radically. In particular, we find that large-scale acceleration is possible without any violation of the energy conditions.