  We recently reported on the existence of a singular resonance in moving media
which arises due to perfect amplitude and phase balance of evanescent waves. We
show here that the non-equilibrium vacuum friction (lateral Casimir-Lifshitz
force) between moving plates separated by a finite gap is fundamentally
dominated by this resonance. Our result is robust to losses and dispersion as
well as polarization mixing which occurs in the relativistic limit.
