  The aim of this communication is to present in a concentrated form the main
ideas of a method, developed by the author, for treating strongly
nonequilibrium collective phenomena typical of the interaction of radiation
with matter, as well as to give a survey of several applications of the method.
The latter is called the Scale Separation Approach since its basic techniques
rely on the possibility of separating different space-time scales in
nonequilibrium statistical systems. This approach is rather general and can be
applied to diverse physical problems, several of which are discussed here.
These problems are: Superradiance of nuclear spins, filamentation in resonant
media, semiconfinement of neutral atoms, negative electric current, and
collective liberation of light.
