Relationship between the speed limit on the brane and in the bulk is
discussed. We assume that the speed of light, similar to the 4-dimensional
gravitational constant, is not a primary fundamental constant but depends on
the gravitational potential of the brane. This opens the way to explain the
hierarchy between the Plank and Higgs scales even within the simplest
5-dimensional model.Comment: RevTeX, 2 pages, no figure
