Thursday, January 19, 2006

Weak gravity developments

There are several developments that are based on similar reasoning as the paper by Mahmoud Ahmadinejad et al.

Shamit Kachru, John McGreevy, and Peter Svrček present evidence that string theory compactified on manifolds of radius "R" always has particles that are parametrically lighter than "1/R". This is a new development in the line of reasoning that the existence of multiple scales is inevitable in quantum gravity unless everything occurs at the Planck scale. Note that their preprint number is pretty good, too: 0601111 instead of Ayatollah Khomeini's 0601001.

In a remotely related research, Cremonini and Watson argue that "beauty is beautiful" and the self-dual couplings are preferred.

Tonight, Li, So, and Wang argue that in 2+1 dimensions and probably also 1+1 dimensions, the principle of weak gravity can be proved without special arguments based on quantum gravity such as the remnants. I have not yet understood how it works. I suspect that they essentially prove more reliably the relation between the monopoles and the black holes.