Dynamics of Complex Systems, Criticality and Record Dynamics

Henrik Jeldtoft Jensen

Imperial College London

Jueves 19/4/2012, 14 hs
Aula Seminario, 2do piso, Pabellón I 

The paradigm of Self-Organised Criticality emphasises systems in a stationary state created by the action of a slow external constant driving rate. SOC postulates that the driven system self-organises to a critical state. In the critical state the system is expected to exhibit abrupt releases of energy in the form of macroscopic events termed avalanches. The focus is on the probability distributions of the even sizes, which are presumed to be scale free power laws in the limit of infinite system size. Candidates for SOC are e.g. earthquakes, rain, forest fires and many others. The scenario of Record Dynamics is concerned with non-stationary and non-critical complex systems undergoing relaxation in order to release a (generalised) internal strain induced at the moment of preparation. The rate of activity decreases as one over time and the distribution of event times follows a Poisson process in logarithmic time. The events sizes can follow any distribution. Systems, which appear to follow the log-Poisson, include spin-glasses, over damped relaxing particle models, models of long time macroevolution and experiments on dynamics of ant colonies.