Non-Singularity of the Exact Two-Dimensional String Black Hole

TL;DR

This paper analyzes the exact two-dimensional string black hole, revealing a non-singular, extended geometry with Euclidean regions and wormholes, contrasting previous semi-classical models.

Contribution

It demonstrates that the exact solution features a non-singular, extended space-time with Euclidean regions and wormholes, unlike earlier semi-classical approximations.

Findings

No singularities in the exact geometry

Presence of Euclidean regions between singularities and horizons

Maximally extended space-time with multiple universes connected by wormholes

Abstract

We study the global structure of the exact two-dimensional space-time which emerges from string theory. Previous work has shown that in the semi-classical limit, this is a black hole similar to the Schwarzschild solution. However, we find that in the exact case, a new Euclidean region appears "between" the singularity and black hole interior. However the boundary between the Lorentzian and Euclidean regions is a coordinate singularity, which turns out to be a surface of time reflection symmetry in an extended space-time. Thus strings having fallen through the black hole horizon would eventually emerge through another one into a new asymptotically flat region. The maximally extended space-time consists of an infinite number of universes connected by wormholes. There are no singularities present in this geometry. We also calculate the mass and temperature associated with the space-time.