We summarise existing experimental results on temperature dependence of activation energy E for structural relaxation. It is demonstrated that it is equal to the activation energy for shear viscoscity of the same substances. The experimental finding is important that E remains temperature dependent when the structure is frozen-in. This, experimentally proven, result rejects the basic assumption of most of the viscosity models, according to which the activation energy is a unique function of configuration entropy and, therfore, should not depend on temperature at a fixed structure. The present experimental results rejects the models based on assumption that activation energy depends only on structure and not on temperature at fixed structure. In this way, it opens up the perspectives for further developments of the theory of molecular mobility.
