This variability is apparently due to a dependence of the dynamics on the initial random equilibrium conformation of the polymer coil. Entropic elasticity is an elasticity with an equilibrium configuration governed by thermodynamic entropy constraints. An ergodic system or process is one in which averages computed from a data sample over time converge, i.e., all sizeable data samples are equally representative of the whole. In general, a dynamical system or process is ergodic if it tends in probability to a limiting form which is independent of the initial conditions. Nonergodic dynamics thus refers to dynamics that never realize a limit independent of initial conditions.
All real processes are nonadiabatic in the sense that some heat exchange always occurs.
But close approximation to an adiabatic ideal can be realized in practice. Also called the time constant of the system. See the website for a complete list.