In Maxwell’s words: “One of the best established facts in thermodynamics is that it is impossible in a system enclosed in an envelope which permits neither chan

In Maxwell’s words: “One of the best established facts in thermodynamics is that it is impossible in a system enclosed in an envelope which permits neither change of volume nor passage of heat, and in which both the temperature and the pressure are everywhere the same, to produce any inequality of temperature or pressure without the expenditure of work. This is the second law of thermodynamics, and it is undoubtedly true as long as we can deal with bodies only in mass, and have no power of perceiving the separate molecules of which they are made up. But if we conceive of a being whose faculties are so sharpened that he can follow every molecule in its course, such a being, whose attributes are still as essentially as finite as our own, would be able to do what is at present impossible to us.” The reason why we can’t move heat from hot to cold is that we don’t know enough. If the demon does know the position of every particle there is no notion of entropy.