Causally pathological spacetimes are physically relevant

TL;DR

This paper challenges the traditional restriction to globally hyperbolic spacetimes in string theory, showing that causally pathological spacetimes can still have consistent dual descriptions, thus broadening the scope of physically relevant models.

Contribution

It demonstrates that spacetimes with causal pathologies, close to closed causal curves, can be physically relevant within string theory, expanding the class of acceptable models.

Findings

Causally pathological spacetimes can have well-behaved dual descriptions

Examples of non-globally hyperbolic spacetimes with consistent physics

Relaxation of causal restrictions in string theory models

Abstract

We argue that in the context of string theory, the usual restriction to globally hyperbolic spacetimes should be considerably relaxed. We exhibit an example of a spacetime which only satisfies the causal condition, and so is arbitrarily close to admitting closed causal curves, but which has a well-behaved dual description, free of paradoxes.