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TL;DR

This paper discusses the irrelevance of spacetime singularities to black hole irreversibility and highlights the challenge of confirming black hole unitarity due to the need for superpositions of many Everett worlds.

Contribution

It proposes that black hole irreversibility can be understood without relying on spacetime singularities and emphasizes the difficulty of experimentally confirming unitarity.

Findings

Spacetime singularities are irrelevant for black hole irreversibility

Confirming black hole unitarity requires superpositions of many Everett worlds

Black hole dynamics can be understood without singularities

Abstract

The existence of spacetime singularities is irrelevant for the irreversible appearance of black holes. However, confirmation of the latter's unitary dynamics would require the preparation of a coherent superposition of a tremendous number of appropriate ``Everett worlds''.