COHERENT NOISE, SCALE-INVARIANCE AND INTERMITTENCY IN LARGE SYSTEMS

We introduce a new class of models in which a large number of ''agents '' organize under the influence of an externally imposed coherent nois e. The model shows reorganization events whose size distribution close ly follows a power law over many decades, even in the case where the a gents do not interact with each other. In addition, the system display s ''aftershock'' events in which large disturbances are followed by a string of others at times which are distributed according to a t(-1) l aw. We also find that the lifetimes of the agents in the system posses s a power-law distribution. We explain all these results using an appr oximate analytic treatment of the dynamics and discuss a number of var iations on the basic model relevant to the study of particular physica l systems.