Anti de Sitter space modelling

[rodsika]

*
Anti de Sitter space is used in the AdS/CFT conjecture. But the universe is composed of de Sitter space. So not*use de Sitter space?* If only*AdS can work in the model, and it's not even representative of our universe, then it may be just wrong. *

 

[haushofer]

Wrong in which sense? That it isn't directly phenomenological? Welcome in the world of theoretical physics!

 

[rodsika]

Wrong in which sense? That it isn't directly phenomenological? Welcome in the world of theoretical physics!

wrong in the sense our universe is not anti de Sitter space. So why use a model that doesn't correspond to our universe. Why can't they use de Sitter space itself (without the "anti"?)

 

[erkokite]

AdS/CFT provides a means of non-perturbatively solving conformal field theories. Many physical QFT's are conformal or close to it (QCD is close for example). Also dualities involving dS spaces have also been discovered. Also the fact that a QFT is dual to a AdS gravity model on one higher dimension is quite profound in itself and seems to have deep connections with holography and by extension things like black hole entropy makes it attractive for study.

 

[atyy]

It's a toy model. It captures aspects of the full problem, which maybe we can better address if we understand a specific case. It's surely not any worse than directed percolation, which according to Wiki was studied for more than 20 years with no experimental realization until Takeuchi et al's http://arxiv.org/abs/0706.4151 .

 

[erkokite]

AdS/CFT actually has had experimental success describing superfluids (and maybe superconductors as well) already.

 

[rodsika]

Anyone here familiar with Lisa Randall RS1 and RS2?
They use 5th dimensional anti de Sitter spaces. Is her model an actual or literal model of
5th dimensional anti de Sitter spaces or is it just based on dualities related to the AdS/CFT correspondence? Meaning the original ideas are quantum field theories in 4D spacetime. Since she doesn't know how to use QFT directly to solve the Hierarchy Problem. She has to use an abstract duality that has no connection to reality by modelling the 5th dimensional as anti de Sitter space. Is this what she was doing? Or is she modelling a literal 5th dimensional anti de Sitter space?

 

[erkokite]

Anyone here familiar with Lisa Randall RS1 and RS2?
They use 5th dimensional anti de Sitter spaces. Is her model an actual or literal model of
5th dimensional anti de Sitter spaces or is it just based on dualities related to the AdS/CFT correspondence? Meaning the original ideas are quantum field theories in 4D spacetime. Since she doesn't know how to use QFT directly to solve the Hierarchy Problem. She has to use an abstract duality that has no connection to reality by modelling the 5th dimensional as anti de Sitter space. Is this what she was doing? Or is she modelling a literal 5th dimensional anti de Sitter space?

It's actually strange that you mentioned this- I answered a similar question on the HEP section yesterday. RS models are AdS/CFT related to some technicolor QFT models. In the RS theories, there are 5 dimensions, however, only the graviton propagates in the 5th dimension. The geometry of the RS1 model is AdS4 plus a finite sized warped 5th dimension (I think that's the way it works). In RS2 the 5th dimension is infinite in size. If you look at the exact metric on the wikipedia page for Randall Sundrum, you can see the exact metric used.