  Self- and cross-correlation dynamics of deeply supercooled liquids were
recently identified using photon correlation spectroscopy and spin relaxometry
on the one hand, and using dielectric investigations on the other. These
results fueled a controversial discussion whether the "generic" response
identified by the former techniques or rather the non-universal dielectric
response reflect the liquid's structural relaxation. The present study employs
physical aging and oscillatory shear rheology to directly access the structural
relaxation of a non-associating glass forming liquid and reveals that
collective equilibrium fluctuations of simple liquids and not single-particle
dynamics govern their structural relaxation.
