Some aspects of pre big bang cosmology

TL;DR

This paper reviews aspects of pre-big bang cosmology, focusing on string theory symmetries, extra dimensions, and the emergence of the universe from initial conditions, suggesting classical singularities may be physically irrelevant.

Contribution

It explores how string theory symmetries and M-theory concepts impact cosmological models, proposing that singularities might not be physically meaningful and that the universe could originate from simple initial states.

Findings

Classical singularities may be physically irrelevant due to string symmetries.

The universe can be modeled to emerge from 'almost nothing' using initial plane waves.

Symmetries of string and M-theory influence cosmological scenarios.

Abstract

This is a summary of a course given at the Fourth Mexican School on Gravitation and Mathematical Physics on some aspects of PBB cosmology. After introductory remarks the lectures concentrate on some amusing consequences derived from the symmetries of the string theory with respect to such classical concepts as isotropy and homogeneity. The extra dimensions and the symmetries of the M theory are further applied to show that the classical singularities might be just physically irrelevant. In the final lecture a model universe is "produced" from "almost nothing" and it is argued that initial plane waves are thermodynamically natural state for the universe to emerge from.