Gravitational Entropy
High Energy Physics - Theory
2025-10-06 v2 General Relativity and Quantum Cosmology
Abstract
We formulate the classical gravitational entropy of a horizon as a Noether charge that does not require the notion of a temperature, and which is applicable to horizons that are not necessarily associated with black holes. This introduces a correction to the covariant phase space formalism that accounts for the configuration-dependence of the generating vector field conjugate to the charge. The vector field is related to the proposal of Bousso that the gravitational entropy of a region is determined by the lightsheet at its boundary. We test the formula on various black hole and cosmological horizons.
Cite
@article{arxiv.2509.10921,
title = {Gravitational Entropy},
author = {Sangmin Choi and Malcolm J. Perry},
journal= {arXiv preprint arXiv:2509.10921},
year = {2025}
}
Comments
23 pages. Fixed typos and added references