The Quantum Theory of General Relativity at Low Energies

TL;DR

This paper discusses how effective field theory provides a consistent framework for understanding quantum gravity at low energies, regardless of whether general relativity is fundamental.

Contribution

It explains the application of effective field theory to general relativity, highlighting its role in low-energy quantum predictions and the limits of the technique.

Findings

Effective field theory enables low-energy quantum gravity predictions.

General relativity can be viewed as a quantum effective field theory.

The technique has well-defined limits at high energies.

Abstract

In quantum field theory there is now a well developed technique, effective field theory, which allows one to obtain low energy quantum predictions in ``non-renormalizable'' theories, using only the degrees of freedom and interactions appropriate for those energies. Whether or not general relativity is truly fundamental, at low energies it is automatically described as a quantum effective field theory and this allows a consistent framework for quantum gravity at ordinary energies. I briefly describe the nature and limits of the technique.