An invitation to loop quantum gravity

TL;DR

This paper introduces loop quantum gravity, highlighting its principles, key results, and potential for experimental tests, aiming to inform physicists across various fields about this background independent quantum gravity approach.

Contribution

It provides a comprehensive overview of loop quantum gravity's assumptions, results, and future prospects, including predictions and open problems, for a broad physics audience.

Findings

Summarizes 35 key results on quantization, matter coupling, and applications.

Discusses prospects for observational tests of quantum gravity.

Highlights the theoretical and phenomenological developments in loop quantum gravity.

Abstract

We describe the basic assumptions and key results of loop quantum gravity, which is a background independent approach to quantum gravity. The emphasis is on the basic physical principles and how one deduces predictions from them, at a level suitable for physicsts in other areas such as string theory, cosmology, particle physics, astrophysics and condensed matter physics. No details are given, but references are provided to guide the interested reader to the literature. The present state of knowledge is summarized in a list of 35 key results on topics including the hamiltonian and path integral quantizations, coupling to matter, extensions to supergravity and higher dimensional theories, as well as applications to black holes, cosmology and Plank scale phenomenology. We describe the near term prospects for observational tests of quantum theories of gravity and the expectations that loop quantum gravity may provide predictions for their outcomes. Finally, we provide answers to frequently asked questions and a list of key open problems.