  We report experimental measurements of particle dynamics in a colloidal glass
in order to understand the dynamical heterogeneities associated with the
cooperative motion of the particles in the glassy regime. We study the local
and global fluctuation of correlation and response functions in an aging
colloidal glass. The observables display universal scaling behavior following a
modified power-law, with a plateau dominating the less heterogeneous short-time
regime and a power-law tail dominating the highly heterogeneous long-time
regime.
