Is it possible to distinguish between reversible and irreversible processes - say, the process of the working substance in a heat engine - via a measurement?
Its a bad question, in the sense that reversible processes don't actually exist, but on the other hand we might want to show via measurement that the process is irreversible - which it is in reality. I think the answer should of course be: no. The equilibrium conditions for a reversible process are too strict.