5 Sep 2007; Mat-Nat Faculty (UiTø), room A228. Wednesday 10:15-12:00

Martin Rypdal

"A stochastic theory for temporal fluctuations in Self-Organized Critical systems".

A short historical review of self-organized criticality will be given, focusing mainly on the attempts to model the fluctuations in the toppling activity of sandpile models. Next I will show how a mean field assumption makes it possible to formulate these problems in terms of a simple stochastic differential equation. Through the corresponding Fokker-Planck equation it is possible to express all the critical exponents of a sandpile model in terms of one parameter, which can be calculated numerically.