I don’t think there’s *any* concrete model, really. From the Sundrum papers it seems one really wants to realize the graviton as an extended object on the scale of 20 microns, while the photon and other known particles remain pointlike. Needless to say, this is a strange picture that doesn’t look like any known field or string theory.

I have wondered about the asymptotic freedom idea you suggest, but I don’t know how it could be realized.

I think whoever first comes up with a good field theoretic or string theoretic framework in which a fat graviton seems plausible will have made major progress.

It seems like I have one or two years to read it all thoroughly. It’s a pity if they want to sit on their results until they themselves can verify with differing experiments. Hopefully the other groups work faster…

Are you shure that string theory is NOT a kind of ( nevertheless constrained ) meta-language of physics that is able to include/express anything? What is blurred at least to an outsider of string theory like me is the relationship between expressivity as a language and it’s own constraints and assumptions. As an analogy: in software development we distinguish between frameworks and applications. A framewok by itself is vacuos ( it can be useless or clumsy but it never maps an application domain in a falsifiable way ). It just defines how applications can be customized with few effort to run under the constraints of the framework. The applications ( ‘theories’ ) are performing the real stuff. In this sense ’string theory’ may be a kind of doubling of theoretical physics within physics, creating a framework for particular theories to work with.

http://motls.blogspot.com/2005/06/deviations-from-newtons-law-seen.html

The summary article was from April and with full references, so it didn’t contain the information you were privileged to have.

Thanks for the info, it looks interesting!

– Down to 100 microns, the tests show no deviation.
– Below 100 microns, they do begin to see some deviation. So far this is unpublished, and might go away. If it does not, it poses a serious problem for string theory. The reason is that string theory can easily explain gravity getting *stronger* at short distances (due to more dimensions being accessible), but not getting *weaker*. It doesn’t immediately invalidate the theory, but no one seems to have any model of how string theory could account for this.
– The fat graviton, to be related to the cosmological constant, implies gravity will be modified below some scale that cannot be much larger than 20 microns. In other words, if the tests find no deviation below about 20 microns, the fat graviton is ruled out. But if the current deviation is confirmed, it’s provides a compelling reason to think about the fat graviton.