Collective modes in open systems of nonlinear random waves

Abstract

Nonlinear random classical waves driven far odd equilibrium by the steady input of energy can support propagating collective models analogous to zero sound in Fermi liquids. The conditions for the existence of these collisionless and dispersionless modes are presented. Applications to a variety of systems as well as experiments to test the theory are suggested. In particular, this article predicts that for gravity waves on the surface of a liquid both longitudinal and transverse collective modes are possible in the collisionless regime.