BRANE

In theoretical physics, a 'brane' or '''p''-brane' is a spatially extended, mathematical concept that appears in string theory and its relatives (M-theory and brane cosmology). The variable ''p'' refers to the spatial dimension of the brane. That is, a 0-brane is a zero-dimensional pointlike particle, a 1-brane is a string, a 2-brane is a "membrane", etc. Every ''p''-brane sweeps out a (''p''+1)-dimensional ''world volume'' as it propagates through spacetime.
Originally string theory was a theory of 1-branes called strings. By the mid-1990s it became apparent that the theory could be extended to also include higher dimensional objects. Typically these objects are ''non-perturbative'' features of the theory (meaning they do not appear in perturbation theory) which is partially why early string theorists were unaware of them.
Besides the fundamental string (or 'F-string') of string theory and its magnetic dual, the NS5-brane, the most important type of branes that appear are the D-branes. Different types of D-branes appear in different theories. Even D''n''-branes for ''n'' appear in type IIA string theory where as the odd D''p''-branes appear in type IIB string theory.
With the development of M-theory, an extra dimension appeared and the fundamental string of string theory became a 2-dimensional membrane called an M2-brane (or supermembrane). Its magnetical dual is an M5-brane. The various branes of string theory are thought to be related to these higher dimensional M5-branes wrapped on various cycles.

Contents

See also

See also

★ Black brane

★ Brane cosmology

★ Cyclic Universe Theory

★ D-brane

★ S-brane