Is it true that for a Carnot cycle, the entropy change for the whole system (engine plus the two reservoirs) would add up to zero? I am reasoning that it would, by the Clausius theorem that for a reversible cycle (which a Carnot cycle is), the entropy change is zero. Otherwise it would not be reversible. Is this correct? And in this case, does this mean that the entropy changes for the two reservoirs (each considered alone) are equal to each other in magnitude but opposite in sign?