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Originally Posted by Arituay
Hello all. This question assumes String/M/Brane theory is correct (big assumption, I know).
Brane cosmology theorizes that gravity is not constrained to our brane. If that were true could the gravity effects we observe from at least a portion of dark matter really be from matter in another brane or in the bulk, meaning we will never truly be able to determine exactly what it is, just that it is reacting gravitationally to create the scaffolding of our galaxies? Has anyone seen this possibility been incorporated into any papers and if so could you point me to them?
Thanks
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I donīt know much about brane cosmologies but the notion of gravity acting across branes through extra dimensions is already disproved by experience.
If such a thing were possible, the GaussīLaw calls for the gravitational flux to spread over those extra dimensions. Since Newton discovered an inverse square law (three dimensions for gravity to act on) instead of inverse N-1 (N dimensions, being N>3), the conclusion is that if those extra dimensions exist, gravity does not act through them. And that holds for brane cosmologies and for whatever cosmology which calls for extra dimensions.
The extra dimensions are not ruled out by this reasoning, just their ability to transmit gravity (or the electromagnetic field).