Sudden change in thermodynamic system.

[Aristarchus0]

Do sudden changes occur in thermodynamic systems? If so, when do they occur and why?

More specifically: When a system is nearing thermodynamic equilibrium, will the process always be slow, gradual, and uniform; or do sudden changes — sudden jumps — sometimes occur?

 

[Andy Resnick]

Classical thermodynamics has nothing to say about *dynamics*- time is not part of the formulation.

There is always fluctuations in physical variables (governed by the fluctuation-dissipation relation), and there is a difference between global measures of equilibrium and local measures of equilibrium (local thermodynamic equilibrium)- Boltzmann's transport equation is a statistical mechanical equation, but the idea is that locally, equilibrium can be reached quickly, giving meaning to thermodynamic quantities like "temperature" when there is a sudden and rapid heat flux.

 

[Sedunov]

The sudden changes take place in thermodynamic systems near phase transition points. For example, bubbles of vapor quickly grow near the boiling point of water.