Number 16 (Story #3), January 10, 1991 by Phillip F. Schewe and Ben Stein SELF ORGANIZED CRITICALITY is the name for the tendency in many large interactive systems to evolve toward a critical state in which a minor event can lead to a chain reaction or catastrophe. According to Brookhaven scientist Per Bak (516-282-3798), the global properties of some composite systems---such as earthquake faults, sandpiles, the stock market, or weather fronts---cannot be understood by studying only parts of the system and that "self organized criticality is the only model or mathematical description that has led to a holistic theory of dynamical systems." Computer modeling has revealed that one characteristic of self organized criticality is a manifestation of a power-law relation; for example, the rate of earthquakes with an energy E is proportional to E raised to a certain power. (Scientific American, January 1991.)