Black Holes without Event Horizons

TL;DR

This paper critiques the traditional use of event horizons in black hole physics, proposing trapping horizons as a more practical and physically meaningful alternative, and explores their implications for thermodynamics and Hawking radiation.

Contribution

It introduces trapping horizons as a viable alternative to event horizons for defining black holes and discusses their potential role in thermodynamics and Hawking radiation.

Findings

Trapping horizons can address drawbacks of event horizons.

Trapping horizons may be linked to black hole thermodynamics.

Hawking radiation can arise from trapping horizons.

Abstract

We discuss some of the drawbacks of using event horizons to define black holes. The reasons are both practical, physical and theoretical. We argue that locally defined trapping horizons can remedy many of these drawbacks. We examine of the question of whether black hole thermodynamics should be associated with event horizons or trapping horizons. To this end we discuss what role trapping horizons may play in black hole thermodynamics. In addition, we show how trapping horizons may give rise to Hawking radiation and discuss the issue of gravitational entropy.