We consider a (4 + d)-dimensional spacetime broken up into a (4 - n)-dimens
ional Minkowski spacetime (where n goes from 1 to 3) and a compact (n + d)-
dimensional manifold. At the present time the n compactification radii are
of the order of the Universe size, while the other d compactification radii
are of the order of the Planck length.