Originally Posted By: Bill S.
Finiter, how do you define "infinitely slowly"?

Infinitely slowly indicates that the system is in a static state of equilibrium. Either the changes in both directions happen at the same rate or no changes happen. Anyway, the system can change in both the directions, but is in a static state if taken as a whole.

Instead of a static state, there can be a dynamic state of equilibrium. Here,the system oscillates between two symmetrically opposite states; here the changes are not infinitely slow, but are smooth as far as the system as a whole is considered. That is, the changes are similar to controlled processes, and not like an explosion.