The Einstein equation of state as the Clausius relation with an entropy production

Abstract

We give a modified derivation of the Einstein equation of state by considering the Clausius relation $T\delta S-\delta N=\delta Q$ on a null hypersurface with a non-vanishing expansion ($\theta \ne 0$), i.e. not in the equilibrium. The derivation corresponds to choosing a specific observer to the hypersurface, and such a generalization gives a hint how we can improve the original derivation by Jacobson. We also give an interpretation of the thermodynamic relation based on the Noether charge method.

16 pages, 2 figures, version to be published in PLB

References in corpus (4)

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• Friedmann Equations of FRW Universe in Scalar-tensor Gravity, f(R) Gravity and First Law of Thermodynamics
• F(R) gravity equation of state
• Entropy density of spacetime and thermodynamic interpretation of field equations of gravity in any diffeomorphism invariant theory