Nonequilibrium Working Group: Working Group Seminar Abstracts

Katja Lindenberg (UCSD)

Date: July 24, 1997

Title: When Disorder Creates Order: Tuning in to Noise

Abstract: The description of physical systems is often quite complex because it involves a large number of degrees of freedom. In reducing the description to the simplest possible, one frequently extracts "important" variables (which may be single degrees of freedom or collective variables) to focus attention on; the many variables that are not treated in detail are then often combined into contributions called "noise." The art of the description lies in choosing the variables to focus on, the properties of the noise that represents all the unchosen variables, and the interaction between them. Noise in this context is usually viewed as the contribution that disturbs or distorts the otherwise orderly or relevant evolution of the variables of interest, that is, as the agent that creates or describes disorder (just look at the definition of noise in any dictionary!). In this talk I will present the case for noise and show that this description has ignored and underestimated the important CONSTRUCTIVE role that noise can play in many physical systems. Indeed, noise can actually be the agent for order. I will show a number of examples where temporal and/or spatial noise actually leads systems into more ordered states.

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