Isotropization in Brane Gas Cosmology

TL;DR

This paper extends Brane Gas Cosmology models to include anisotropies and demonstrates that the universe naturally evolves towards isotropy, providing insights into the uniformity of large spatial dimensions.

Contribution

It generalizes BGC equations to anisotropic cases and shows isotropization emerges naturally from the dynamics.

Findings

Isotropization occurs dynamically in anisotropic BGC models.

The generalized equations support the natural evolution towards isotropy.

Results suggest a mechanism for the observed uniformity of large spatial dimensions.

Abstract

Brane Gas Cosmology (BGC) is an approach to unifying string theory and cosmology in which matter is described by a gas of strings and branes in a dilaton gravity background. The Universe is assumed to start out with all spatial dimensions compact and small. It has previously been shown that in this context, in the approximation of neglecting inhomogeneities and anisotropies, there is a dynamical mechanism which allows only three spatial dimensions to become large. However, previous studies do not lead to any conclusions concerning the isotropy or anisotropy of these three large spatial dimensions. Here, we generalize the equations of BGC to the anisotropic case, and find that isotropization is a natural consequence of the dynamics.