Phys. Rev. Lett. 110, 011601 (2013)

The existence of extra dimensions, beyond those of space and time that we perceive, is an attractive hypothesis in theoretical physics, not least in trying to fathom the apparent weakness of gravity compared with other forces. Compactification of those extra dimensions is necessary, to put them beyond our notice (even, so far, in high-energy experiments such as those at the Large Hadron Collider) — an idea that dates back to the work of Theodor Kaluza and Oskar Klein in the 1920s. Models developed since then include that of Lisa Randall and Raman Sundrum in 1999, involving branes and warped geometry, achieving localization of the graviton through the curvature of the Universe.

Ira Z. Rothstein, however, has an alternative — and 'localization' is the clue. Just as Anderson localization restricts the diffusion of waves in a disordered medium, could gravity be localized in a disordered 'crystal' lattice of branes? According to Rothstein, one or more extra dimension riddled with defects is all that is needed for gravitational localization and, consequently, for the existence of arbitrarily large extra dimensions.