Why the glass transition problem remains unsolved?

Glass-forming substances are made of units having nontrivial mutual interactions. Therefore, structural relaxation of glass-formers is a many-body relaxation problem, which unfortunately is still an unsolved problem in statistical mechanics. Conventional theories and models of glass transition bypass solution of this problem, and hence glass transition also remains an unsolved problem. There are plenty of experimental evidences for the many-body relaxation dynamics, and some examples are given. The Coupling Model of the author is not a full solution of the many-body relaxation problem either. Nevertheless, its predictions can explain the properties of structural relaxation originating from many-body relaxation and their relations to its precursor, namely the Johari–Goldstein secondary relaxation. A demonstration of the utility of the Coupling Model is given here by solving two problems in glass transition that involve many-body relaxation. The problems are: (1) the breakdown of Stokes–Einstein and Debye–Stokes–Einstein relations in neat molecular glass-formers and colloidal suspension, and (2) the component dynamics of polymer blends and mixtures of non-polymeric glass-formers.