  Via molecular dynamics simulations of a generic glass former in the
supercooled and normal liquid states, it is shown that spatial correlations of
strain fluctuations exhibit a crossover from the well-established power-law
$\sim 1/r^3$-decay at long wavelengths to an exponential behavior, $\sim
\exp(-r/l_{\text {c}})$ at intermediate distances. The characteristic length of
the exponential decay grows both with temperature and time via, $l_{\text
{c}}^2 \propto D(T)\, t$, with $D(T)$ being the temperature-dependent diffusion
coefficient. This suggests that the crossover between the power-law and
exponential decays is governed by a diffusion process.
