  We demonstrate that the time evolution of the van Hove dynamical pair
correlation function is governed by adiabatic forces that arise from the free
energy and by superadiabatic forces that are induced by the flow of the van
Hove function. The superadiabatic forces consist of drag, viscous, and
structural contributions, as occur in active Brownian particles, in liquids
under shear and in lane forming mixtures. For hard sphere liquids we present a
power functional theory that predicts these universal force fields in
quantitative agreement with our Brownian dynamics simulation results.
