  We present the 5-dimensional cosmological solutions in the Randall-Sundrum
warped compactification scenario, using the Goldberger-Wise mechanism to
stabilize the size of the extra dimension. Matter on the Planck and TeV branes
is treated perturbatively, to first order. The back-reaction of the scalar
field on the metric is taken into account. We identify the appropriate
gauge-invariant degrees of freedom, and show that the perturbations in the bulk
scalar can be gauged away. We confirm previous, less exact computations of the
shift in the radius of the extra dimension induced by matter. We point out that
the physical mass scales on the TeV brane may have changed significantly since
the electroweak epoch due to cosmological expansion, independently of the
details of radius stabilization.
