BraneWorld Gravity
Abstract
The observable universe could be a 1 + 3surface (the "brane") embedded in a 1 + 3 + ddimensional spacetime (the "bulk"), with Standard Model particles and fields trapped on the brane while gravity is free to access the bulk. At least one of the d extra spatial dimensions could be very large relative to the Planck scale, which lowers the fundamental gravity scale, possibly even down to the electroweak (∼ TeV) level. This revolutionary picture arises in the framework of recent developments in M theory. The 1 + 10dimensional M theory encompasses the known 1 + 9dimensional superstring theories, and is widely considered to be a promising potential route to quantum gravity. General relativity cannot describe gravity at high enough energies and must be replaced by a quantum gravity theory, picking up significant corrections as the fundamental energy scale is approached. At low energies, gravity is localized at the brane and general relativity is recovered, but at high energies gravity "leaks" into the bulk, behaving in a truly higherdimensional way. This introduces significant changes to gravitational dynamics and perturbations, with interesting and potentially testable implications for highenergy astrophysics, black holes, and cosmology. Braneworld models offer a phenomenological way to test some of the novel predictions and corrections to general relativity that are implied by M theory. This review discusses the geometry, dynamics and perturbations of simple braneworld models for cosmology and astrophysics, mainly focusing on warped 5dimensional braneworlds based on the RandallSundrum models.
 Publication:

Living Reviews in Relativity
 Pub Date:
 June 2004
 DOI:
 10.12942/lrr20047
 arXiv:
 arXiv:grqc/0312059
 Bibcode:
 2004LRR.....7....7M
 Keywords:

 String Theory;
 General Relativity and Quantum Cosmology;
 Astrophysics;
 High Energy Physics  Phenomenology;
 High Energy Physics  Theory
 EPrint:
 Corrections, improvements, new references