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'''Brane cosmology''' is a ] motivated by, but not rigorously derived from, ] and ]. The idea is to solve problems in ] using speculative ] theories and in turn use cosmological observations to motivate ideas in ]. '''Brane cosmology''' is a ] motivated by, but not rigorously derived from, ] and ]. The idea is to solve problems in ] using speculative ] theories and in turn use cosmological observations to motivate ideas in ].


The central idea is that our visible, four-dimensional ] is entirely restricted to a D3] embedded in a ] ], called the bulk. The additional ]s may be taken to be ], in which case the observed universe contains the extra dimensions, and then no reference to the bulk is appropriate in this context. In the bulk model, other branes may be moving through this bulk. Interactions with the bulk, and possibly with other branes, can influence our brane and thus introduce effects not seen in more standard cosmological models. The central idea of the braneworld scenario is that our visible, three-dimensional ] is entirely restricted to a D3] embedded in a ] ], called the bulk. The additional ]s may be taken to be ], in which case the observed universe contains the extra dimensions, and then no reference to the bulk is appropriate in this context. In the bulk model, other branes may be moving through this bulk. Interactions with the bulk, and possibly with other branes, can influence our brane and thus introduce effects not seen in more standard cosmological models.


As one of its attractive features, the model can "explain" the weakness of ] relative to the other fundamental forces of nature. In the brane picture, the other three forces (] and the ] and ] nuclear forces) are localised on the ], but gravity has no such constraint and so much of its attractive power "leaks" into the bulk. As a consequence, the force of gravity should appear significantly stronger on small (sub-millimetre) scales, where less gravitational force has "leaked". Various experiments are currently underway to test this. For example, in a particle accelerator, if a graviton were to be discovered and then observed to suddenly disappear, it might be assumed that the graviton "leaked" into the bulk. As one of its attractive features, the model can "explain" the weakness of ] relative to the other fundamental forces of nature. In the brane picture, the other three forces (] and the ] and ] nuclear forces) are localised on the ], but gravity has no such constraint and so much of its attractive power "leaks" into the bulk. As a consequence, the force of gravity should appear significantly stronger on small (sub-millimetre) scales, where less gravitational force has "leaked". Various experiments are currently underway to test this. For example, in a particle accelerator, if a graviton were to be discovered and then observed to suddenly disappear, it might be assumed that the graviton "leaked" into the bulk.

Revision as of 12:29, 3 May 2006

Brane cosmology is a protoscience motivated by, but not rigorously derived from, superstring theory and M-theory. The idea is to solve problems in cosmology using speculative particle physics theories and in turn use cosmological observations to motivate ideas in string theory.

The central idea of the braneworld scenario is that our visible, three-dimensional universe is entirely restricted to a D3brane embedded in a higher-dimensional spacetime, called the bulk. The additional dimensions may be taken to be compact, in which case the observed universe contains the extra dimensions, and then no reference to the bulk is appropriate in this context. In the bulk model, other branes may be moving through this bulk. Interactions with the bulk, and possibly with other branes, can influence our brane and thus introduce effects not seen in more standard cosmological models.

As one of its attractive features, the model can "explain" the weakness of gravity relative to the other fundamental forces of nature. In the brane picture, the other three forces (electromagnetism and the weak and strong nuclear forces) are localised on the brane, but gravity has no such constraint and so much of its attractive power "leaks" into the bulk. As a consequence, the force of gravity should appear significantly stronger on small (sub-millimetre) scales, where less gravitational force has "leaked". Various experiments are currently underway to test this. For example, in a particle accelerator, if a graviton were to be discovered and then observed to suddenly disappear, it might be assumed that the graviton "leaked" into the bulk.

The Randall-Sundrum, pre-big bang, ekpyrotic and cyclic scenarios are particular models of brane cosmology which have attracted a considerable amount of attention.

Detection

If this theory is correct why cant we see/establish our D3brane's existance? In M-Theory on open string vibrations produce light and not closed strings and these must move within the D3brane making it impossible to see it by making it completely invisible. Closed stings gravitons would allow us to detect the D3brane since they are closed strings.

The Big Bang Brane Cosmological Theory

Is a theory that two parallel branes in the bulk bumped into one another and the point of contact resulted in the Big Bang.

See also

External links

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