In this chapter we discuss several ways in which laser physics makes contact with other fields and contributes to them. In Sec. 21-1 we mention a few sub­ jects that have been laser dominated, for example, nonlinear optics and light scattering. In Secs. 21-2, 21-3, and 21-4 we outline recent research ef­ forts which, in our opinion, provide good examples of how the techniques ap­ plied extensively in the laser analysis may be profitably applied to other prob­ lems in nonequilibrium quantum statistical mechanics. These problems also involve open systems and are influenced by nonlinear coherent and inco­ herent events. It is reasonable, then, to expect that the techniques which have been extensively studied and applied to problems such as the laser will have wide application in other areas. Specifically, three problems have been chosen for presentation here:

a. A philosophical interpretation of laser “quasimodes” (Appendix B) in terms of the “true” modes of the universe.