Cooperative electromagnetic effects

Collective phenomena in strongly nonequilibrium systems interacting with an electromagnetic field are considered. Such systems are described by compli cated nonlinear differential or integro-differential equations. The aim of this review is to show that many nonlinear collective phenomena can be succ essfully treated by a recently developed method called the scale separation approach, whose name comes from the idea of separating different character istic space-time scales existing in nonequilibrium statistical systems. Thi s approach is rather general and can be applied to various nonequilibrium p hysical problems, several of which are discussed here. The problems conside red not only serve as illustrations of the method but are quite important b y themselves, presenting interesting physical effects such as the collectiv e liberation of light, turbulent photon filamentation, superradiant spin re laxation, negative electric current, and the magnetic semiconfinement of at oms.