Beyond the Einstein Equation of State: Wald Entropy and Thermodynamical Gravity

TL;DR

This paper demonstrates that classical gravity equations can be derived from thermodynamic principles using Wald entropy, indicating gravity's potential thermodynamic origin across all diffeomorphism-invariant theories.

Contribution

It establishes a general derivation of gravity equations from thermodynamics using Wald entropy for any diffeomorphism-invariant theory.

Findings

Gravity equations follow from thermodynamic relation dQ = T dS

Wald entropy applies to local Rindler horizons

Supports gravity's thermodynamic origin

Abstract

We show that the classical equations of gravity follow from a thermodynamic relation, dQ = T dS, where S is taken to be the Wald entropy, applied to a local Rindler horizon at any point in spacetime. Our approach works for all diffeomorphism-invariant theories of gravity. This suggests that classical gravity may be thermodynamic in origin.