His reputation in oceanography was primarily founded on a set of papers on non-linear interactions in ocean waves. In these he adapted Feynman diagram formalism to classical random wave fields. He later discovered plasma physicists were applying similar techniques to plasma waves, and that he had rediscovered some results of Rudolf Peierls explaining the diffusion of heat in solids by non-linear phonon interactions. This led him to review the field of plasma physics, rekindling an earlier interest in Quantum Field Theory.