Universal relaxation and diffusion in interacting complex systems: Fundamental physics and rich applications

Abstract

The purpose of this paper is to make the research communities aware of the universality of the dynamic properties of many-body relaxation/diffusion processes of different kinds manifested in experiments and simulations on condensed matter with diverse chemical compositions and physical structures. I shall demonstrate the universality first from the dynamic processes in glass-forming systems. This is reinforced by strikingly similar properties of different processes in contrasting interacting systems all having nothing to do with glass transition. The examples given here include glassforming systems of diverse chemical composition and physical structures, conductivity relaxation of ionic conductors (liquid, glassy and crystalline), translation and orientation ordered phase of rigid molecule, and polymer chain dynamics. Universality is found in the change of dynamics when dimension is reduced to nanometer size in widely different systems. Many more examples are given in Relaxation and Diffusion in Complex Systems, Springer, New York, (2011). The remarkable universality indicates that many-body relaxation/diffusion is governed by fundamental physics to be unveiled. One candidate is classical chaos in the theoretical basis of the Coupling Model, the predictions of which are in accord with the universal properties.