New entropies, black holes, and holographic dark energy

TL;DR

This paper introduces a new entropy framework that unifies various entropy proposals, applies it to black holes and holographic dark energy, and explores its implications for early universe inflation and the Hubble tension.

Contribution

It proposes a novel entropy construct that combines existing ideas and satisfies key properties, with applications to cosmology and black hole physics.

Findings

Potential to induce early universe inflation

May help resolve the Hubble tension

Provides consistent black hole thermodynamics

Abstract

The Bekenstein-Hawking entropy is a cornerstone of horizon thermodynamics but quantum effects correct it, while inequivalent entropies arise also in non-extensive thermodynamics. Reviewing our previous work, we advocate for a new entropy construct that comprises recent and older proposals and satisfies four minimal key properties. The new proposal is then applied to black holes and to holographic dark energy and shown to have the potential to cause early universe inflation or to alleviate the current Hubble tension. We then analyze black hole temperatures and masses consistent with alternative entropies.