Black hole entropy and long strings

TL;DR

This paper explores whether black hole entropy is due to short or long range microstates, proposing that long strings in matrix quantum mechanics better explain the entropy with realistic energy scales.

Contribution

It introduces the long string phenomenon as a mechanism to reconcile black hole entropy with microstates, addressing limitations of short-range models.

Findings

Long strings lower excitation energy per degree of freedom.

The mechanism aligns microscopic degrees of freedom with Bekenstein-Hawking entropy.

Short range models face energy scale issues.

Abstract

We discuss whether black hole entropy counts short or long range microstates in quantum gravity. In brick wall and induced gravity models the entropy arises due to short distance correlations across the event horizon cut off at the Planck length. However, the energy of these short range degrees of freedom is too high compared to the black hole energy. We argue that the long string phenomenon, which naturally appears in matrix quantum mechanics, resolves this issue by lowering the excitation energy per degree of freedom. This mechanism also reduces the total number of microscopic degrees of freedom in a given volume, leading to a correct estimate of the Bekenstein-Hawking formula for black hole entropy.