  We present a quantitative study of strain correlations in quiescent
supercooled liquids and glasses. Recent two-dimensional computer simulations
and experiments indicate that even supercooled liquids exhibit long-lived,
long-range strain correlations. Here we investigate this issue in three
dimensions via experiments on hard sphere colloids and molecular dynamics
simulations of a glass forming binary Lennard Jones mixture. Both in the glassy
state and in the supercooled regime, strain correlations are found to decay
with a $1/r^{3}$ power-law behavior, reminiscent of elastic fields around an
inclusion. Moreover, theoretical predictions on the time dependence of the
correlation amplitude are in line with the results obtained from experiments
and simulations. It is argued that the size of the domain, which exhibits a
"solid-like" cooperative strain pattern in a supercooled liquid, is determined
by the product of the speed of sound with the structural relaxation time. While
this length is of the order of nanometers in the normal liquid state, it grows
to macroscale when approaching the glass transition.
