brane cosmology

Any of various theories that describe the universe in terms of multidimensional objects called branes. A brane can have any number of spatial dimensions. A 0-brane is a zero-dimensional object, and can represent a point-like particle. A 1-brane is a one-dimensional or string-like object; in string theory vibrational states of 1-branes represent elementary particles. A 2-brane is a two-dimensional object, or membrane (from which the word brane is derived).

The familiar world of three spatial dimensions and one time dimension can be described as a 4-brane (three space dimensions and one time dimension) moving in a higher-dimensional universe called the bulk. In some brane cosmology theories, there are many other universes (branes), moving through the bulk, which sometimes interact with each other. According to ekpyrotic theory, before the Big Bang our universe was a contracting brane that collided with another brane. This triggered the Big Bang and the creation of matter and radiation.

Other brane cosmologies describe the whole universe as a 10- or 11-dimensional brane in which most of the dimensions are invisible to us – perhaps because they have been ‘rolled up’ so that they are extremely small. However, it is also possible in some models for large or even infinite dimensions to exist, yet be concealed from us.