and 
relaxation processes in melts and glasses. Experimental data have been used to show that different types of relaxation in oxide systems
can be interrelated to each other. The molecular mechanism of viscous flow in inorganic systems has been dis-
cussed in detail with the use of continuum theories (elasticity and hydrodynamics) developed in the works by
the author in 1967–2007. A rigorous relationship between the volumes of atoms overcoming the activation bar-
rier, the instantaneous shear modulus, and the barrier itself (free activation energy) has been derived. This rela-
tionship allows one to calculate the sizes of atoms involved in the viscous flow with a deviation that does not
exceed 10% of the values determined by direct structural methods. In this case, empirically chosen constants
are absent. Based on the results obtained by Anderson and Stewart (1954) and the author (1974), it has been
established that the activation energy for ionic conduction can be calculated using similar notions. It has been
demonstrated for the first time that the universal relation between the viscosity and conductivity over a wide
range of temperatures (for alkali-containing oxide melts) i.e., the Littleton equation, finds a simple quantitative
explanation in the framework of the same models, even though the mechanisms of both processes do not depend
on each other.