Thursday, August 27, 2009

Is N=8 supergravity finite?

Kram sent to me a link to a highly interesting popular article relating to N=8 supergravity. Zvi Bern and collaborators have been able make a progress in attempt to prove the finiteness of N=8 supergravity. Work has been done during one decade: good to learn during the age of hyper hype physics that work in this time scale is still done. For some reason the work has not been commented by Lubos nor by others. If the finiteness is true, one can only admire the incredible power of Einstein's conceptualization.

I have not anything interesting to say about the topic but I can give link to Vanquishing Infinity: Old Methods Lead To New Approach To Finding Quantum Theory Of Gravity.


At 7:25 PM, Blogger Javier said...

Hi matti.

I must correct you. Lubos has actually devoted various posts to the question of finiteness of supergravity.

His statements is that despite he agrees that probably that theories are actually UV finite they still are incomplete and they need teh aditional states/configrations of string theory to make a viable theory.

In facteven in the early egithie it was sonn realized that supergravity theories (eve the most phenomenologically promising, eleven dimensional N=1 supergravity) didn't allow viable models. To beguin with they didn't allow the right content of chiral fermions.

Still a clear proof of the finiteness is a good thing, but possibly mostly of cademic interest instead of physical interest.

At 10:42 PM, Blogger Matti Pitkanen said...

Yes. I have read postings of Lubos. The work in question was however kind of a big summary so that I would have expected some kind of reaction since even the director of Max Planck institute praised the work.

I agree about stringy mathematics and in TGD framework the slicing of space-time surfaces by string world sheets labeled by points of partonic 2-surfaces leads to a stringy description when partonic 2-surfaces are replaced by finite number of points carrying fermionic quantum numbers. The orbits of these points at light-like 3-surface representing moving parton define braid strands light-like curves.

One has almost topological QFT in the following sense. The braind strands at different partonic 2-surfaces are connected by strings. This gives rise to interacton and one does not have a mere topological QFT anymore.

An amusing analogy is dancers in parquettes defined by partonic 2-surfaces. The feet of dancers at different parquettes are connected by strings. During dance the strings connecting their feet get braided so that the dance as dynamic representation of braiding is coded to a space-like braiding of strings. The interpration is as coding of dynamical dancing pattern to memory.

This picture actually applies to the TGD based model of topological quantum computation in which DNA nucleotides and lipids of cell membrane are connected by magnetic flux tubes defining the braid strands and lipids are the dancers and dance is induced by the flow of lipids forming liquid crystal.


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