Self-Organized Criticality in complex Systems

摘要

Many diverse systems exhibir scale-invariant spatial and temporal fluctuations. Which are manifested by algebraic decay fo correlations. We survey the possibility of self-organized criticaility, which attempts to explain the ubiquity of such critical behavior, in traffic flow and biological evolution. THe trafficflow is described by the traffic equation in the hydrodynamic limit, and shown to exhibit a variety fo behaviors such as homogneeous flow. Chaotic behavior, and density waves with scale-invariant fluctuations. The biological evolution problem is studied with a view to incorporating random mutation and natural selection. THe resulting lifetime ddistribution of species displays power-law behavior with an exponent close to two. Which is consisten with the fossil data.