2004/08/31 by Lee Smolin · 137 citations
Physics and Astronomy · #Black Holes and Theoretical Physics #Immirzi parameter #Loop quantum cosmology #Loop quantum gravity #Noncommutative and Quantum Gravity Theories #Physics #Quantum #Quantum Mechanics and Applications #Quantum gravity #Quantum mechanics #Spin foam #Theoretical physics #hep-th
paper · pdf · doi:10.1142/9789812702340_0078
50 pages, to be submitted to Reviews of Modern Physics
openalex publication_date 2004/10/01 · arxiv created 2005/06/28 · arxiv updated 2017/08/23 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
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.