Definition of a Brane in String Theory

In theoretical physics, a brane (short for membrane) is an object which can have any number of allowed dimensions. Branes are most popular for their presence in string theory, where it is a fundamental object, along with the string. String Theory String theory has 9 space dimensions, so a brane can have anywhere from 0 to 9 dimensions. Branes were hypothesized as part of string theory in the late 1980s. In 1995, Joe Polchinski realized that Edward Wittens proposed M-Theory required the existence of branes. Some physicists have proposed that our own universe is, in fact, a 3-dimensional brane, on which we are stuck within a larger 9-dimensional space, to explain why we cant perceive the extra dimensions. Also Known As: membrane, D-brane, p-brane, n-brane