Nonequilibrium Transitions Induced by External White and Coloured Noise

Abstract

It is a very general observation that the environment of nonequilibrium systems, be they natural systems or laboratory systems, is at best only constant on the average. The environment is very complex and thus unavoidably its temporal behaviour appears to be random. In other words, the system perceives the environment as a noise source. A good illustration of this is the population of, say, some animal species. Its growth is determined by factors such as the birth rate, mortality, abundance of predators etc. which are strongly influenced by climatic conditions and therefore show a more or less pronounced variability. More generally, the fluctuations of the environment, which are called external noise, can be understood as the expression of a turbulent or chaotic state of the surroundings.