The thermal entropy density of spacetime

TL;DR

This paper introduces the concept of thermal entropy density in spacetime, showing it can be defined without prior assumptions of temperature or horizons, and suggesting a deep link between thermodynamics and gravity.

Contribution

It defines thermal entropy density for arbitrary spacetimes without relying on temperature or horizons, highlighting its geometric and gravitational significance.

Findings

Thermal entropy density can be obtained without temperature or horizon assumptions.

Gravity influences the thermal entropy density, indicating a thermodynamic aspect of gravity.

Thermal entropy density can be geometrized, linking thermodynamics and spacetime geometry.

Abstract

We introduce the notion of thermal entropy density, and first obtain the thermal entropy density of any arbitrary spacetime without firstly assuming a temperature or a horizon. The results indicate that gravity possesses thermal effects or therm entropy density possesses effects of gravity. The results also imply that, besides gravity, the thermal entropy density can also be geometrized.