Physics

Brane-Induced Inflation

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Science  12 May 2006:
Vol. 312, Issue 5775, pp. 815
DOI: 10.1126/science.312.5775.815c

Inflationary cosmology seeks to explain such puzzling features of the universe as the extreme flatness of spacetime and the mutual similarity of distant regions of space that are not causally connected. A universe experiencing breakneck inflationary expansion would exhibit these and other observed characteristics, but the standard model of particle physics lacks any identifiable quantum particle, or inflaton, that could underlie this phenomenon.

A brane is a spacetime structure that inhabits the higher dimensional spaces (the “bulk”) required by “theories of everything,” such as string theory and M theory, and some specific assemblage of branes might act as inflatons. Shuhmaher and Brandenberger offer a model of cosmological inflation in which a hot gas of branes drives expansion of the high-dimensional bulk spacetime. At first, all spatial dimensions are extremely compact, and extra dimensions above the usual three are tucked away into a topological space called an orbifold. As the brane gas expands, its energy density decreases until the three familiar spatial dimensions can undergo conventional inflationary expansion. — DV

Phys. Rev. Lett. 96, 161301 (2006).

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