Spherically symmetric trapping horizons, the Misner-Sharp mass and black hole evaporation

TL;DR

This paper explores how trapping horizons, rather than event horizons, can define black holes in a way that supports unitary evolution, linking the Misner-Sharp mass to black hole thermodynamics, Hawking radiation, and evaporation.

Contribution

It proposes that trapping horizons, characterized by the Misner-Sharp mass, provide a local and potentially more complete framework for understanding black hole dynamics and information preservation.

Findings

Trapping horizons can be used to define black holes without event horizons.

Misner-Sharp mass relates directly to black hole thermodynamics and Hawking radiation.

Insights into black hole collapse and evaporation processes are gained through this framework.

Abstract

Understood in terms of pure states evolving into mixed states, the possibility of information loss in black holes is closely related to the global causal structure of spacetime, as is the existence of event horizons. However, black holes need not be defined by event horizons, and in fact we argue that in order to have a fully unitary evolution for black holes, they should be defined in terms of something else, such as a trapping horizon. The Misner-Sharp mass in spherical symmetry shows very simply how trapping horizons can give rise to black hole thermodynamics, Hawking radiation and singularities. We show how the Misner-Sharp mass can also be used to give insights into the process of collapse and evaporation of locally defined black holes.