  We analyze data from confocal microscopy experiments of a colloidal
suspension to validate predictions of rapid sporadic events responsible for
structural relaxation in a glassy sample. The trajectories of several thousand
colloidal particles are analyzed, confirming the existence of rapid sporadic
events responsible for the structural relaxation of significant regions of the
sample, and complementing prior observations of dynamical heterogeneity. The
emergence of relatively compact clusters of mobility allows the dynamics to
transition between the large periods of local confinement within its potential
energy surface, in good agreement with the picture envisioned long ago by Adam
and Gibbs and Goldstein.
