Complex Adaptive Matter
Professor George Gruner
University of California at Los Angeles
Department of Physics
405 Hilgard Avenue
Los Angeles, CA 90024
(310) 825-8782
(310) 825-5734 FAX
The essential ingredients
My definition of CAM is a material with the following essential features:
many relevant degrees of freedom. By relevant I mean that these degrees of freedom play an essential role in the response to external perturbation.
close to an instability or close to the condition for the emergence of a new order parameter.
nonlinear coupling and a feedback mechanism ñ together with the action-reaction principle
I am not sure whether all the above are important for adaptation but they appear to play an essential role in the systems which are listed below.
Some of the consequences
There are (or may be) a variety of consequences as far as the response to external parameters or drives is concerned:
large and nonlinear response to small perturbations
order parameter segregation and spatial structure formation
divergent time scales
hysteresis, metastability, and possibly memory
self organized criticality
Model systems
Interacting electron systems (heavy fermions, oxides, linear chain conductors) close to broken symmetry
Driven many degree of freedom systems (Density waves, Josephson arrays, vortex crystals etc.)
Self assemblies, biomaterials
Some glasses with nonlinear coupling
Many of the phenomena which are listed under 2. Are readily observed in these systems, but often are described using a different language.
Relevant probes
There are several probes which are particularly useful in addressing these issues:
Probes with spatial sampling (MRI, scanning probes etc.)
Low energy spectroscopies (to explore modes which extend to zero energies)
In addition access to the variation of external parameters, such as P, T, H and E (electric field) are essential.