Time in quantum gravity

TL;DR

This paper explores how quantum gravity theories like quantum general relativity and string theory inform our understanding of the nature of physical time, focusing on which aspects are fundamental or emergent.

Contribution

It reviews lessons from quantum gravity approaches on the fundamental versus emergent nature of time in physics.

Findings

Insights into the nature of time from quantum gravity theories

Discussion on which aspects of time are fundamental or emergent

Implications for the understanding of physical time in quantum gravity

Abstract

Quantum gravity--the marriage of quantum physics with general relativity--is bound to contain deep and important lessons for the nature of physical time. Some of these lessons shall be canvassed here, particularly as they arise from quantum general relativity and string theory and related approaches. Of particular interest is the question of which of the intuitive aspects of time will turn out to be fundamental, and which 'emergent' in some sense.