Entropy increase during physical processes for black holes in Lanczos-Lovelock gravity

TL;DR

This paper demonstrates that Wald entropy for black holes in Lanczos-Lovelock gravity increases monotonically during quasi-stationary processes, supporting its physical interpretation and extending the area increase theorem to broader gravitational theories.

Contribution

It proves the monotonic increase of Wald entropy during physical processes in Lanczos-Lovelock gravity, generalizing the black hole area theorem beyond Einstein's theory.

Findings

Wald entropy increases during quasi-stationary processes

Supports the physical interpretation of Wald entropy in Lanczos-Lovelock gravity

Extends the area increase theorem to a wider class of gravitational theories

Abstract

We study quasi-stationary physical process for black holes within the context of Lanczos-Lovelock gravity. We show that the Wald entropy of stationary black holes in Lanczos-Lovelock gravity monotonically increases for quasi-stationary physical processes in which the horizon is perturbed by the accretion of positive energy matter and the black hole ultimately settles down to a stationary state. This result reinforces the physical interpretation of Wald entropy for Lanczos-Lovelock models and takes a step towards proving the analogue of the black hole area increase-theorem in a wider class of gravitational theories.