Dynamical Origin of the Entropy of a Black Hole

TL;DR

A new invariant statistical mechanical definition of black-hole entropy is proposed and it is shown that the main contribution to the entropy is given by thermally excited "invisible" modes propagating in the close vicinity of the horizon.

Abstract

Modes of physical fields which are located inside a horizon and which cannot be observed by a distant observer are identified with dynamical degrees of freedom of a black hole. A new invariant statistical mechanical definition of a black-hole's entropy is proposed. It is shown that the main contribution to the entropy is given by thermally excited `invisible' modes propagating in the close vicinity of the horizon. A calculation based on the proposed definition yields a value of the entropy which is in good agreement with the usually adopted value.