English

Geometric conservation in curved spacetime and entropy

High Energy Physics - Theory 2025-01-07 v4 General Relativity and Quantum Cosmology Fluid Dynamics

Abstract

We provide an improved definition of new conserved quantities derived from the energy-momentum tensor in curved spacetime by introducing an additional scalar function. We find that the conserved current and the associated conserved charge become geometric under a certain initial condition of the scalar function, and show that such a conserved geometric current generally exists in curved spacetime. Furthermore, we demonstrate that the geometric conserved current agrees with the entropy current in an effective theory of a perfect fluid, thus the conserved charge is the total entropy of the system. While the geometric charge can be regarded as the entropy for a nondissipative fluid, its physical meaning should be investigated for more general cases.

Keywords

Cite

@article{arxiv.2312.09712,
  title  = {Geometric conservation in curved spacetime and entropy},
  author = {Sinya Aoki and Yoshimasa Hidaka and Kiyoharu Kawana and Kengo Shimada},
  journal= {arXiv preprint arXiv:2312.09712},
  year   = {2025}
}

Comments

16 pages (single column), 1 figure, references added, the proposal for the geometric current is slightly modified

R2 v1 2026-06-28T13:52:14.811Z