Ten Theses on Black Hole Entropy

TL;DR

This paper offers a perspective on black hole thermodynamics, suggesting that entropy arises from horizon degrees of freedom, is finite due to spacetime discreteness, and obeys the second law because of non-unitary exterior dynamics.

Contribution

It introduces a novel viewpoint linking horizon structure, spacetime discreteness, and non-unitary evolution to black hole entropy and thermodynamics.

Findings

Entropy derives from horizon degrees of freedom

Spacetime discreteness makes entropy finite

Non-unitary dynamics ensure the second law holds

Abstract

I present a viewpoint on black hole thermodynamics according to which the entropy: derives from horizon "degrees of freedom"; is finite because the deep structure of spacetime is discrete; is "objective" thanks to the distinguished coarse graining provided by the horizon; and obeys the second law of thermodynamics precisely because the effective dynamics of the exterior region is not unitary.