多体相互作用体系中的弛豫与扩散:一个尚未解决的问题

文章目的在于引起国内研究团体对一系列复杂相互作用体系中的弛豫和扩散的普适性进行关注.研究发现，无论是不同的化学结构（如无机物、有机物、聚合物、生物分子、胶体、金属和离子导电材料），还是不同的物理状态（如晶态、玻璃态、液体、熔体、混合体系和含水系统），以及不同的尺度（如从块体至纳米），这种普适性无处不在 ［K.L.Ngai.Relaxation and Diffusion in Complex Systems.New York:Springer,2011］.该现象起源于多体系统的不可逆过程，取决于一些基本物理定律，与非简谐势引发的经典混沌有关.重新认识这种普适性不仅对众多不同领域的发展有利，而且能进一步弄清楚多体系统中的弛豫与扩散问题—— 一个重要而又未解决的物理问题.作者提出的耦合模型尽管不是一个严格而完整的答案，但却能够预测多体系统的弛豫和扩散特征，而且与实验结果吻合.基于该模型，绝大多数多体系统中的弛豫与扩散行为是相似的.该模型有望为这一难题的彻底解决奠定基石.

Universal relaxation and diffusion in many-body interacting systems:an outstanding unsolved problem

The purpose of this article is to bring the attention of research communities in China to the universal properties of relaxation and diffusion in a variety of complex systems with interactions.This remarkable universality has been brought out from experimental findings in inorganic,organic,polymeric,bio-molecular,colloidal,metallic,and ionically conducting systems with diverse chemical structures,and in various physical states including crystalline,glassy,liquid,molten,mixed,and hydrated,and with dimensions ranging from bulk to nano-meter size ［K.L.Ngai, Relaxation and Diffusion in Complex Systems.New York:Springer,2011］.The universal properties originate from the many-body nature of the irreversible processes, which are governed by some fundamental physics related to classical chaos originating from the anharmonic interaction potential. Recognition of the universality not only benefits research in many different fields, but also makes clear that many-body relaxation and diffusion in complex interacting systems is an important and unsolved problem in physics.Although it is neither a rigorous nor complete solution,the author's Coupling Model has given successful predictions about the universal properties of relaxation and diffusion,many of which are anomalous,in various different systems.It can be used as a stepping stone in the construction of a rigorous and fundamental theory to solve the problem,once and for all.