The prevalent approaches for explaining why we do not encounter anti-thermodynamic evolutions is that those are extremely a-typical or unlikely. Essentially the same issue arises in the context of the standard approaches to quantum statistical mechanics (see ). That is, the Demon is not a practical proposal for constructing a device that would violate the Second Law of thermodynamics, but rather a statement to the effect that the Second Law cannot be universally true if the laws of mechanics are universally true.Īttempts to prove the Second Law as a universal theorem in classical statistical mechanics, encounter the following issue: since the fundamental microscopic dynamics is invariant under velocity reversal, one can show that given any Hamiltonian, if there are entropy-increasing trajectory segments in the system’s state space, then there are also entropy-decreasing ones, and so the thermodynamic law cannot be strictly true. Maxwell’s Demon is a way of demonstrating that the laws of mechanics are compatible with microstates and Hamiltonians that lead to an evolution which violates the Second Law of thermodynamics by transferring heat from a cold gas to a hot one without investing work. In this paper we show that a Maxwellian Demon is compatible with standard quantum mechanics.
Maxwell devised his so-called Demon in 1867 to show that the Second Law of thermodynamics cannot be universally true if classical mechanics is universally true. One implication of our analysis is that the Second Law cannot provide a universal lawlike basis for an account of the arrow of time this account has to be sought elsewhere. We discuss what might be the quantum mechanical counterpart of the classical notion of “macrostates”, thus explaining why our Quantum Demon setup works not only at the micro level but also at the macro level, properly understood. We address in our analysis the connection between measurement and erasure interactions and we show how these notions are applicable in the microscopic quantum mechanical structure. Our discussion is in the framework of standard quantum mechanics we give two separate arguments in the framework of quantum mechanics with and without the projection postulate. We do so by analyzing a particular (but highly idealized) experimental setup and proving that it violates the Second Law. In this paper we demonstrate that Maxwell’s Demon is also compatible with quantum mechanics. We have shown (in a number of publications) by a general state-space argument that Maxwell’s Demon is compatible with classical mechanics, and that the most recent solutions, based on Landauer’s thesis, are not general. Various attempts to “exorcise” the Demon, by proving that it is impossible for one reason or another, have been made throughout the years, but none of them were successful. Since the Second Law is taken by many to provide an arrow of time, the threat to its universality threatens the account of temporal directionality as well. Maxwell in 1867 in order to show that the Second Law of thermodynamics is not universal, since it has a counter-example. Maxwell’s Demon is a thought experiment devised by J.
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