Absence of initial singularities in superstring cosmology

TL;DR

This paper explores how string theory's unique features, like T-duality and string thermodynamics, can eliminate the initial singularity problem in cosmology, offering a classical resolution to a fundamental issue.

Contribution

It demonstrates that string theory's degrees of freedom and symmetries can naturally resolve the initial singularity in cosmology, contrasting with standard point-particle models.

Findings

String theory's degrees of freedom avoid classical singularities.

T-duality implies a minimum size for the universe.

High-energy string thermodynamics suggests a non-singular beginning.

Abstract

In a universe whose elementary constituents are point particles there does not seem to be any obvious mechanism for avoiding the initial singularities in physical quantities in the standard model of cosmology. In contrast in string theory these singularities can be absent even at the level where spacetime is treated classically. This is a consequence of the basic degrees of freedom of strings in compact spaces, which necessitate a reinterpretation of what one means by a very small universe. We discuss the basic degrees of freedom of a string at the classical and quantum level, the minimum size of strings (string uncertainty principle), the t-duality symmetry, and string thermodynamics at high energy densities, and then describe how these considerations suggest a resolution of the initial singularity problem. An effort has been made to keep this writeup self-contained and accessible to non-string theorists.