The Penrose Inequality as a Constraint on the Low Energy Limit of Quantum Gravity

TL;DR

This paper explores the Penrose inequality in Anti-de Sitter space, proposing it as a swampland criterion that constrains the low-energy limit of quantum gravity and analyzing its validity across various scalar potentials.

Contribution

It introduces the Penrose inequality as a new swampland condition, provides methods to test its violation with scalar potentials, and proves its validity under certain energy conditions.

Findings

Constructed initial data violating the inequality with scalar fields.

Found no violations for string theory-derived potentials.

Provided analytic conditions for inequality violation.

Abstract

We construct initial data violating the Anti-deSitter Penrose inequality using scalars with various potentials. Since a version of the Penrose inequality can be derived from AdS/CFT, we argue that it is a new swampland condition, ruling out holographic UV completion for theories that violate it. We produce exclusion plots on scalar couplings violating the inequality, and we find no violations for potentials from string theory. In the special case where the dominant energy condition holds, we use GR techniques to prove the AdS Penrose inequality in all dimensions, assuming spherical, planar, or hyperbolic symmetry. However, our violations show that this result cannot be generically true with only the null energy condition, and we give an analytic sufficient condition for violation of the Penrose inequality, constraining couplings of scalar potentials. Like the Breitenlohner-Freedman bound, this gives a necessary condition for the stability of AdS.