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Maxwell’s Demon in Quantum Mechanics

by 1,* and 2
Department of Philosophy, The Hebrew University of Jerusalem Mount Scopus, Jerusalem 91905, Israel
Department of Philosophy, University of Haifa, Haifa 31905, Israel
Author to whom correspondence should be addressed.
Entropy 2020, 22(3), 269;
Received: 5 February 2020 / Revised: 22 February 2020 / Accepted: 24 February 2020 / Published: 27 February 2020
(This article belongs to the Special Issue Time and Entropy)
Maxwell’s Demon is a thought experiment devised by J. C. Maxwell in 1867 in order to show that the Second Law of thermodynamics is not universal, since it has a counter-example. 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. 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. 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. In this paper we demonstrate that Maxwell’s Demon is also compatible with quantum mechanics. We do so by analyzing a particular (but highly idealized) experimental setup and proving that it violates the Second Law. 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 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. 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. 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. View Full-Text
Keywords: entropy; Maxwell’s Demon; the second law of thermodynamics; arrow of time entropy; Maxwell’s Demon; the second law of thermodynamics; arrow of time
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MDPI and ACS Style

Shenker, O.; Hemmo, M. Maxwell’s Demon in Quantum Mechanics. Entropy 2020, 22, 269.

AMA Style

Shenker O, Hemmo M. Maxwell’s Demon in Quantum Mechanics. Entropy. 2020; 22(3):269.

Chicago/Turabian Style

Shenker, Orly; Hemmo, Meir. 2020. "Maxwell’s Demon in Quantum Mechanics" Entropy 22, no. 3: 269.

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