Dynamical Cobordisms in General Relativity and String Theory

TL;DR

This paper constructs exact, time-dependent solutions in string and M-theory that smoothly connect different string theories and compactifications without horizons, allowing physical propagation between regions and maintaining perturbative control.

Contribution

It introduces a class of exact, interpolating solutions in string/M-theory that connect different theories and compactifications through expanding domain walls without causal horizons.

Findings

Solutions are exact and alpha-prime corrected.

Regions are connected by expanding domain walls.

Solutions can asymptote to supersymmetry at late times.

Abstract

We describe a class of time-dependent solutions in string- or M-theory that are exact with respect to alpha-prime and curvature corrections and interpolate in physical space between regions in which the low energy physics is well-approximated by different string theories and string compactifications. The regions are connected by expanding "domain walls" but are not separated by causal horizons, and physical excitations can propagate between them. As specific examples we construct solutions that interpolate between oriented and unoriented string theories, and also between type II and heterotic theories. Our solutions can be weakly curved and under perturbative control everywhere and can asymptote to supersymmetric at late times.