Small-Scale Structure of Spacetime: Bounds and Conjectures
Abstract
Description
This review consists of two parts. The first part establishes certain astrophysical bounds on the smoothness of classical spacetime. Some of the best bounds to date are based on the absence of vacuum Cherenkov radiation in ultrahigh-energy cosmic rays. The second part discusses possible implications of these bounds for the quantum structure of spacetime. One conjecture is that the fundamental length scale of quantum spacetime may be different from the Planck length.
20 pages; invited talk at the Third Mexican Meeting on Mathematical and Experimental Physics, September 10-14, 2007, El Colegio Nacional, Mexico City; v3: final version
20 pages; invited talk at the Third Mexican Meeting on Mathematical and Experimental Physics, September 10-14, 2007, El Colegio Nacional, Mexico City; v3: final version