From General Relativity to Quantum Gravity

TL;DR

This paper reviews various approaches to quantum gravity that treat spacetime as a dynamic entity, highlighting key strategies, results, and open issues over the past few decades.

Contribution

It provides an overview of leading quantum gravity approaches emphasizing the dynamical nature of spacetime from general relativity.

Findings

Gravitons and classical spacetime emerge in suitable limits

Different short-distance dynamics from classical GR

Key strategies and open issues in quantum gravity

Abstract

In general relativity (GR), spacetime geometry is no longer just a background arena but a physical and dynamical entity with its own degrees of freedom. We present an overview of approaches to quantum gravity in which this central feature of GR is at the forefront. However, the short distance dynamics in the quantum theory are quite different from those of GR and classical spacetimes and gravitons emerge only in a suitable limit. Our emphasis is on communicating the key strategies, the main results and open issues. In the spirit of this volume, we focus on a few avenues that have led to the most significant advances over the past 2-3 decades.