Entropy of Causal Horizons

TL;DR

This paper explores the thermodynamic properties of causal horizons in spacetime, proposing that their observer dependence and associated entropy have a quantum mechanical origin, linking gravity and thermodynamics.

Contribution

It provides a deeper understanding of the quantum mechanical basis for the thermodynamic behavior of causal horizons and their observer dependence.

Findings

Causal horizons have observer-dependent temperature and entropy.

Horizon thermodynamics can be derived from quantum field theory considerations.

A geometric interpretation of horizons as information membranes is supported.

Abstract

We analyze spacetimes with horizons and study the thermodynamic aspects of causal horizons, suggesting that the resemblance between gravitational and thermodynamic systems has a deeper quantum mechanical origin. We find that the observer dependence of such horizons is a direct consequence of associating a temperature and entropy to a spacetime. The geometrical picture of a horizon acting as a one-way membrane for information flow can be accepted as a natural interpretation of assigning a quantum field theory to a spacetime with boundary, ultimately leading to a close connection with thermodynamics.