Black hole evaporation in a heat bath as a nonequilibrium process and its final fate

TL;DR

This paper models black hole evaporation within a heat bath as a nonequilibrium thermodynamic process, revealing faster evaporation, energetic bursts, and potential remnants, advancing understanding of black hole thermodynamics.

Contribution

It applies recent nonequilibrium thermodynamics to black hole evaporation, highlighting effects of heat baths on evaporation dynamics and final states.

Findings

Evaporation time shortens due to nonequilibrium effects.

A large energy burst occurs at the end of evaporation.

A Planck-sized remnant likely remains post-evaporation.

Abstract

When a black hole evaporates, there arises a net energy flow from black hole into its outside environment (heat bath). The existence of energy flow means that the thermodynamic state of the whole system, which consists of the black hole and the heat bath, is in a nonequilibrium state. Therefore, in order to study the detail of evaporation process, the nonequilibrium effects of the energy flow should be taken into account. Using the nonequilibrium thermodynamics which has been formulated recently, this paper shows the following: (1) Time scale of black hole evaporation in a heat bath becomes shorter than that of the evaporation in an empty space (a situation without heat bath), because a nonequilibrium effect of temperature difference between the black hole and heat bath appears as a strong energy extraction from the black hole by the heat bath. (2) Consequently a huge energy burst (stronger than that of the evaporation in an empty space) arises at the end of semi-classical stage of evaporation. (3) It is suggested that a remnant of Planck size remains after the quantum stage of evaporation in order to guarantee the increase of total entropy of the whole system.