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arXiv · 2509.10921

Gravitational Entropy

Sangmin Choi·Malcolm J. Perry
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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.

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Sangmin Choi, Malcolm J. Perry. 2025-09-13. Gravitational Entropy. https://doi.org/10.1088/1361-6382%2Fae60de

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