Claus Wilke

Scaling in Non-Equilibrium Systems: Alternatives to Self-Organized Criticality

Non-equilibrium systems displaying scale-free behavior have attracted much interest in recent years. Very often one or several typical quantities of a system under empirical study are distributed according to a power law. This calls for an explanation. A lot of research over the last decade has been devoted to self-organized criticality as the main concept to explain the observed distributions. However, there are other mechanisms that can produce a similar behavior. A short introduction into some of these mechanisms, like multiplicative stochastic processes or coherent-noise processes, will be given. Thereafter, emphasis will be laid on some recent results about coherent-noise models, in particular with regard to aftershocks and hierarchical noise.