Brane universes

[Sauron]

I have readed a bit about them in an interview to Lisa Randall.


I have an idea of what they are. But don´t know the detaills of how it is working. That is, they implment the idea of supernumerary dimensios because only gravity can leave the brane (a d-brane if i am not wrong) while the other interactions are fixed to kee in the brane.

But i would like to know it in more detaill. I didn´t find a good exposition (in fact no exposition) avaiable in line. So in if somene (Jeff?) knows it i would acknowledege a lot if he could give here an explanation. Or at least point a good review.


T.I.A.

P.S. AS you can see althought my prefered theory is LQG i keep open minded to advances in alternative aproximation to QG, as string theory [:D]

[meteor]

I don't know very much about the subject, but seems that there are two approaches to solve the problem of gravitation
In one model our universe is a D-brane, and particles with spin -1 are open strings with its ends glued to the D-brane. The graviton,has spin-2, is a close string and is not glued to the D-brane, and somehow can travel to other dimensions, this is why gravitation is so feeble
The other model, the Randall-Sundrum model consist in that our universe is 3-dimensional brane that is parallel to another 3-dimensional brane. This two branes are inside a 5-dimensional spacetime (the bulk). Gravity resides in the other brane, so it has a weak effect in our brane