  The aging dynamics of a colloidal glass has been studied by multiangle
Dynamic Light Scattering, Neutron Spin Echo, X-ray Photon Correlation
Spectroscopy and Molecular Dynamics simulations. The two relaxation processes,
microscopic (fast) and structural (slow), have been investigated in an
unprecedentedly wide range of time and length scales covering both ergodic and
nonergodic regimes. The microscopic relaxation time remains diffusive at all
length scales across the glass transition scaling with wavevector Q as Q^{-2}.
The length-scale dependence of structural relaxation time changes from
diffusive, characterized by a Q^{-2}-dependence in the early stages of aging,
to Q^{-1}- dependence in the full aging regime which marks a discontinuous
hopping dynamics. Both regimes are associated with a stretched behaviour of the
correlation functions. We expect these findings to provide a general
description of both relaxations across the glass transition.
