Role of Various Entropies in the Black Hole Information Loss Problem

TL;DR

This paper discusses the different roles of various entropy types in the black hole information loss paradox, emphasizing the distinction between fine and coarse grained information and exploring implications for quantum gravity.

Contribution

It highlights the importance of different entropy concepts in understanding black hole information loss and proposes a framework for their roles in quantum gravity.

Findings

Coarse grained information may be lost in black hole processes.

Fine grained information is preserved under unitary evolution.

Potential development of quantum gravity analogues of classical irreversible equations.

Abstract

In a recent paper Hawking has argued that there is no information loss in black holes in asymptotically AdS spacetimes. We remind that there are several types of information (entropy) in statistical physics -- fine grained (microscopic) and coarse grained (macroscopic) ones which behave differently under unitary evolution. We suggest that the coarse grained information of the rest of the Universe is lost while fine grained information is preserved. A possibility to develop in quantum gravity an analogue of the Bogoliubov derivation of the irreversible Boltzmann and Navier - Stokes equations from the reversible mechanical equations is discussed.