Liquid elasticity length, universal dynamic crossovers and glass transition

Abstract

We discuss two main universal dynamic crossovers in a liquid that correspond to relaxation times of 1 ps and 10^{-7}--10^{-6} s. We introduce the concept of liquid elasticity length $d_{\rm el}$. At room temperature, $d_{\rm el}$ is several \AA in water and increases to 0.01 mm in honey and 1 mm in tar. We discuss that on temperature decrease, $d_{\rm el}=d_{\rm m}$ and $d_{\rm el}=L$ correspond to the two dynamic crossovers, where $d_{\rm m}$ is the medium-range order and L is system size. The second crossover defines all kinetic aspects of the glass transition whereas ``thermodynamic'' glass transition is realized in the limit of infinite system size only. One prediction of this picture is the increase of viscosity with the size of macroscopic system, which we verify by measuring the viscosity of honey.