  We derive a non-equilibrium fluctuation-dissipation relation for bosonic
correlation functions from holography in the classical gravity approximation at
strong coupling. This generalizes the familiar thermal fluctuation-dissipation
relation in absence of external sources. This also holds universally for any
non-equilibrium state which can be obtained from a stable thermal equilibrium
state in perturbative derivative (hydrodynamic) and amplitude
(non-hydrodynamic) expansions. Therefore, this can provide a strong
experimental test for the applicability of the holographic framework. We
discuss how it can be tested in heavy ion collisions. We also make a conjecture
regarding multi-point holographic non-equilibrium Green's functions.
