  The understanding of glassy dynamics above the devitrification temperature of
a glass remains poorly understood. Here, we use real-time AFM imaging to build
a spatio-temporal map of the relaxation dynamics of a highly stable glass into
its supercooled liquid. This new methodology enables a direct visualization of
the progression of the liquid phase and clarifies and quantifies the presence
of localized fast mobility regions separated by giant length scales. Our data
permit to establish a clear correlation between dynamic length and time scales
in glasses. This approach may also be applicable to unveil the microscopic
structure and dynamics of other glass forming systems with much shorter length
and time scales, including liquid-cooled glasses.
