Time-reparametrization invariances, multithermalization and the Parisi scheme

The Parisi scheme for equilibrium and the corresponding slow dynamics with multither-malization -same temperature common to all observables, different temperatures only possible at widely separated timescales - imply one another. Consistency requires that two systems brought into infinitesimal coupling be able to rearrange their timescales in order that all their temperatures match: this time reorganisation is only possible be-cause the systems have a set of time-reparametrization invariances, that are thus seen to be an essential component of the scenario.