Dynamical Topology Change, Compactification and Waves in String Cosmology

TL;DR

This paper presents exact string solutions with time-varying moduli fields that demonstrate dynamical topology change, compactification, and wave-like behaviors, offering insights into string cosmology and the limitations of effective theories.

Contribution

It introduces new exact solutions in string cosmology illustrating topology change, dynamic compactification, and wave phenomena, with discussions on effective theory validity.

Findings

Examples of dynamical topology change in string solutions

Solutions showing dynamic compactification of dimensions

Identification of wave-like solutions without scale hierarchy

Abstract

Exact string solutions are presented, where moduli fields are varying with time. They provide examples where a dynamical change of the topology of space is occurring. Some other solutions give cosmological examples where some dimensions are compactified dynamically or simulate pre-big bang type scenarios. Some lessons are drawn concerning the region of validity of effective theories and how they can be glued together, using stringy information in the region where the geometry and topology are not well defined from the low energy point of view. Other time dependent solutions are presented where a hierarchy of scales is absent. Such solutions have dynamics which is qualitatively different and resemble plane gravitational waves. (Talk given at the Trieste Spring School and Workshop, 1994.)