Snowmass White Paper: Micro- and Macro-Structure of Black Holes

TL;DR

This paper reviews how string theory's fuzzball and microstate geometry programs offer a promising resolution to the black-hole information paradox by modeling black holes as horizonless, microstructure-rich objects.

Contribution

It provides an overview of the fuzzball and microstate geometry approaches, summarizing their progress, current status, and future research directions in resolving the black-hole information paradox.

Findings

Fuzzball and microstate geometries resolve the information paradox.

Black holes can be modeled as horizonless, microstructure-rich objects.

String theory uniquely provides the degrees of freedom needed for this resolution.

Abstract

The black-hole information paradox provides a stringent test of would-be theories of quantum gravity. String theory has made significant progress toward a resolution of this paradox, and has led to the fuzzball and microstate geometry programs. The central thesis of these programs is that only string theory has sufficiently many degrees of freedom to resolve black-hole microstructure, and that horizons and singularities are artifacts of attempting to describe gravity using a theory that has too few degrees of freedom to resolve the physics. Fuzzballs and microstate geometries recast black holes within string theory as horizonless and singularity-free objects that not only resolve the paradox but provide new insight into the underlying microstructure. We give an overview of this approach, summarize its current status and describe future prospects and insights that are now within reach.