The nature of spacetime singularities

TL;DR

This paper surveys the current understanding of spacetime singularities in classical general relativity, discussing key theories, hypotheses, and future research directions.

Contribution

It provides a comprehensive overview of classical spacetime singularities, including the BKL picture, cosmic censorship, and recent insights into black hole singularities.

Findings

BKL picture's relevance to cosmological singularities

Connections between cosmic censorship and null singularities

Insights into matter singularities and critical collapse

Abstract

Present knowledge about the nature of spacetime singularities in the context of classical general relativity is surveyed. The status of the BKL picture of cosmological singularities and its relevance to the cosmic censorship hypothesis are discussed. It is shown how insights on cosmic censorship also arise in connection with the idea of weak null singularities inside black holes. Other topics covered include matter singularities and critical collapse. Remarks are made on possible future directions in research on spacetime singularities.