Summary

Self-organised criticality combines the ideas of self-organisation in dissipative structures with those of critical phenomena in equilibrium second-order phase transitions, in an attempt to explain the frequent appearance of scale-free statistical laws that summarize events in many complex systems. It has been suggested that SOC might be the mechanism behind the Gaia hypothesis of Lovelock, where the earth is treated as a single organism far from equilibrium. More ambitiously there is an attempt by Smolin to explain the complexity of the universe also in this approach. As yet, a comprehensive analytical understanding of SOC, comparable to that of critical phenomena in equilibrium second-order phase transitions, is lacking but some work has been done (see, for example, Ref.[2] and references therein).