Introduction to the Effective Field Theory Description of Gravity

TL;DR

Gravity can be consistently treated as a low-energy effective field theory, separating known GR physics from unknown high-energy physics. The approach uses a background-field quantization and a derivative expansion of the action, absorbing ultraviolet divergences into higher-dimension operators while yielding robust, nonlocal quantum predictions at low energy. The key result is that quantum corrections to gravity—although extremely small—are calculable and governed by nonanalytic loop terms, with concrete predictions such as a small quantum correction to the Newtonian potential. This framework clarifies the regime of validity for quantum gravity, provides a practical method for computations, and guides future explorations of potential phenomenology and high-energy completions.

Abstract

This is a pedagogical introduction to the treatment of general relativity as a quantum effective field theory. Gravity fits nicely into the effective field theory description and forms a good quantum theory at ordinary energies.