Levels of spacetime emergence in quantum gravity

TL;DR

This paper discusses various levels of spacetime emergence in quantum gravity, highlighting the technical and conceptual challenges at each stage of reconstructing classical spacetime from quantum descriptions.

Contribution

It introduces a framework of multiple levels of spacetime emergence, clarifying the reconstruction process and its associated technical and conceptual issues in quantum gravity.

Findings

Identifies multiple levels of spacetime emergence in quantum gravity.

Highlights technical challenges at each emergence level.

Raises philosophical questions about the nature of spacetime.

Abstract

We explore the issue of spacetime emergence in quantum gravity, by articulating several levels at which this can be intended. These levels correspond to the reconstruction moves that are needed to recover the classical and continuum notion of space and time, which are progressively lost in a progressively deeper sense in the more fundamental quantum gravity description. They can also be understood as successive steps in a process of widening of the perspective, revealing new details and new questions at each step. Each level carries indeed new technical issues and opportunities, and raises new conceptual issues. This deepens the scope of the debate on the nature of spacetime, both philosophically and physically.