RESPONSE THEORY OF INTERFACES, SUPERLATTICES AND COMPOSITE-MATERIALS

This short contribution to the Gates Festschrift on ''Surface Science: The First Thirty Years'' describes how a simple general theory develo ped. It is the story of the formation of a useful mathematical languag e for the study of surfaces, interfaces, superlattices and composite m aterials. Personal accounts of the evolution of the theory are given a nd illustrations come mostly from the field of vibrations. This paper tries also to emphasize the benefits wrought by such a fundamental res earch.