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Comment on `Quantum Solution to the Arrow-of-Time Dilemma' of L. Maccone arXiv:0802.0438

Oleg Kupervasser, Dimitri N. Laikov

Published Apr 30, 2010• 1 citation
OpenAlex

Abstract

A recent Letter by Maccone presents a solution to the arrow-of-time dilemma based on existing laws of quantum mechanics. He argues that all phenomena where the entropy decreases must not leave any information (in the observer's memory) of their having happened, the observer being a part of the whole system. He concludes that quantum mechanics is necessary to his argument, which he thinks does not otherwise work in classical mechanics. This Comment and the previously published Comment of Jennings, Rudolph describes flaws in Maccone's arguments. However, the main argument (observer's memory erasing) previously formulated in the works by one of us (O.K.) and repeated by Maccone is correct under conditions described in this Comment. Moreover, this argument can be used for resolving a reduction paradox (Schrodinger Cat paradox) in quantum mechanics. In part fourth time arrows synchronization (decohorence) is discussed. In part fifth time arrows synchronization (decohorence) in quantum gravity is discussed. This Comment consists of five parts. The first one is written by Oleg Kupervasser and Dimitri Laikov. The second, third, fourth and fifth ones are written by Oleg Kupervasser only.

Related papers

"New Cybernetics and the Application of its Principles in Physics" and "Comment on "Quantum Solution to the Arrow-of-Time Dilemma" of L. Maccone arXiv:0802.0438"

Oleg Kupervasser, Dimitri N. Laikov

The first paper: We describe principles of new cybernetics and use these principles for resolution of basic physical paradoxes. It demonstrates universality of the principles of new cybernetics. The second paper: recent letter by Maccone presents a solution based on the existing laws of quantum mechanics to the arrow-of-time dilemma. He argues that all phenomena in which the entropy decreases must not leave any information (in the observer's memory) of their having occurred because the observer is a part of the whole system. Maccone concludes that quantum mechanics is necessary to his argument, which he believes does not otherwise work in classical mechanics. This Comment consists of four parts. We discuss the basic problems in the first part. This Comment and the previously published Comment by Jennings and Rudolph describes flaws in Maccone's arguments. However, the main argument (erasure of the observer's memory), which was previously formulated in our work and was repeated by Maccone, is correct under the conditions described in this Comment. Moreover, this argument can be used to resolve a reduction paradox (the Schrodinger's Cat paradox) in quantum mechanics. This use is demonstrated in the second part. In the third part, the synchronisation (decoherence) of time arrows is discussed. In the fourth part, the synchronisation (decoherence) of time arrows in quantum gravity is considered.

arXiv:0911.2610•Nov 13, 2009•2 citations

Comment on “Entanglement and the Thermodynamic Arrow of Time” and Correct Reply on “Comment on "Quantum Solution to the Arrow-of-Time Dilemma"” of David Jennings and Terry Rudolph

Kupervasser Oleg

Recently David Jennings and Terry Rudolph published two papers as reaction on Maccone’s paper Quantum Solution to the Arrow-of-Time Dilemma. In these papers, the authors suppose that second law of thermodynamics is not relevant for quantum systems. Unfortunately, these papers did not get relevant reply from Maccone. The reason of this is following. Both Maccone and the above-mentioned authors use thermodynamic law and thermodynamic-like terminology for non-thermodynamic systems, for example, microscopic system of three qubits. However, big size of a system (quantum or classic) is also not an enough condition for a system to be macroscopic. The macroscopic system must also be chaotic and has small chaotic interaction with its environment/observer resulting in decoherence (decorrelation). We demonstrate that for relevant thermodynamic macroscopic quantum systems no objection appears.

arXiv:1304.7850•Frontiers in Science•Jan 7, 2013•7 citations

Comment on “Quantum Solution to the Arrow-of-Time Dilemma”

David H. Jennings, Terry Rudolph

Recently, a substantial amount of debate has grown up around a proposed quantum resolution to the `arrow of time dilemma' that is based on the role of classical memory records of entropy-decreasing events. In this note we show that the argument is incomplete and furthermore, by providing a counter-example, argue that it is incorrect. Instead of quantum mechanics providing a resolution in the manner suggested, it allows enhanced classical memory records of entropy-decreasing events.

arXiv:0909.1726•Physical Review Letters•Apr 9, 2010•21 citations

The Thermodynamic Arrow-of-time and Quantum Mechanics

Lorenzo Maccone

I give an explanation of the thermodynamic arrow-of-time (namely entropy increases with time) within a quantum mechanical framework. This entails giving a solution to the Loschmidt paradox, i.e. showing how an irreversible macro-dynamics can arise from a reversible micro-dynamics. I argue that, in accordance to the reversible dynamics, both entropy-increasing and entropy-decreasing transformations take place, but entropy-decreasing transformations cannot leave any information of their having happened. This is indistinguishable from their not having happened at all. The second law of thermodynamics is then reduced to a tautology: the only transformations that can be seen are those where entropy does not decrease. However, typicality arguments seem to prevent this argument to be used as a complete solution to the arrow-of-time dilemma: it might still be necessary to postulate a low entropy initial state for the system under consideration.

Electronic Notes in Theoretical Computer Science•Feb 1, 2011•0 citations

A quantum solution to the arrow-of-time dilemma: reply

Lorenzo Maccone

I acknowledge a flaw in the paper "A quantum solution to the arrow of time dilemma": as pointed out by Jennings and Rudolph, (classical) mutual information is not an appropriate measure of information. This can be traced back to the quantum description underlying my analysis, where quantum mutual information is the appropriate measure of information. The core argument of my paper (summarized in its abstract) is not affected by this flaw. Nonetheless, I point out that such argument may not be adequate to account for all phenomena: it seems necessary to separately postulate a low entropy initial state.

arXiv:0912.5394•Dec 30, 2009•3 citations

Quantum Solution to the Arrow-of-Time Dilemma

Lorenzo Maccone

The arrow-of-time dilemma states that the laws of physics are invariant for time inversion, whereas the familiar phenomena we see everyday are not (i.e., entropy increases). I show that, within a quantum mechanical framework, all phenomena which leave a trail of information behind (and hence can be studied by physics) are those where entropy necessarily increases or remains constant. All phenomena where the entropy decreases must not leave any information of their having happened. This situation is completely indistinguishable from their not having happened at all. In the light of this observation, the second law of thermodynamics is reduced to a mere tautology: physics cannot study those processes where entropy has decreased, even if they were commonplace.

arXiv:0802.0438•Physical Review Letters•Aug 17, 2009•84 citations
A recent Letter by Maccone presents a solution to the arrow-of-time dilemma based on existing laws of quantum mechanics. He argues that all phenomena where the entropy decreases must not leave any information (in the observer's memory) of their having happened, the observer being a part of the whole system. He concludes that quantum mechanics is necessary to his argument, which he thinks does not otherwise work in classical mechanics. This Comment and the previously published Comment of Jennings, Rudolph describes flaws in Maccone's arguments. However, the main argument (observer's memory erasing) previously formulated in the works by one of us (O.K.) and repeated by Maccone is correct under conditions described in this Comment. Moreover, this argument can be used for resolving a reduction paradox (Schrodinger Cat paradox) in quantum mechanics. In part fourth time arrows synchronization (decohorence) is discussed. In part fifth time arrows synchronization (decohorence) in quantum gravity is discussed. This Comment consists of five parts. The first one is written by Oleg Kupervasser and Dimitri Laikov. The second, third, fourth and fifth ones are written by Oleg Kupervasser only.
The first paper: We describe principles of new cybernetics and use these principles for resolution of basic physical paradoxes. It demonstrates universality of the principles of new cybernetics. The second paper: recent letter by Maccone presents a solution based on the existing laws of quantum mechanics to the arrow-of-time dilemma. He argues that all phenomena in which the entropy decreases must not leave any information (in the observer's memory) of their having occurred because the observer is a part of the whole system. Maccone concludes that quantum mechanics is necessary to his argument, which he believes does not otherwise work in classical mechanics. This Comment consists of four parts. We discuss the basic problems in the first part. This Comment and the previously published Comment by Jennings and Rudolph describes flaws in Maccone's arguments. However, the main argument (erasure of the observer's memory), which was previously formulated in our work and was repeated by Maccone, is correct under the conditions described in this Comment. Moreover, this argument can be used to resolve a reduction paradox (the Schrodinger's Cat paradox) in quantum mechanics. This use is demonstrated in the second part. In the third part, the synchronisation (decoherence) of time arrows is discussed. In the fourth part, the synchronisation (decoherence) of time arrows in quantum gravity is considered.
Recently David Jennings and Terry Rudolph published two papers as reaction on Maccone’s paper Quantum Solution to the Arrow-of-Time Dilemma. In these papers, the authors suppose that second law of thermodynamics is not relevant for quantum systems. Unfortunately, these papers did not get relevant reply from Maccone. The reason of this is following. Both Maccone and the above-mentioned authors use thermodynamic law and thermodynamic-like terminology for non-thermodynamic systems, for example, microscopic system of three qubits. However, big size of a system (quantum or classic) is also not an enough condition for a system to be macroscopic. The macroscopic system must also be chaotic and has small chaotic interaction with its environment/observer resulting in decoherence (decorrelation). We demonstrate that for relevant thermodynamic macroscopic quantum systems no objection appears.
I give an explanation of the thermodynamic arrow-of-time (namely entropy increases with time) within a quantum mechanical framework. This entails giving a solution to the Loschmidt paradox, i.e. showing how an irreversible macro-dynamics can arise from a reversible micro-dynamics. I argue that, in accordance to the reversible dynamics, both entropy-increasing and entropy-decreasing transformations take place, but entropy-decreasing transformations cannot leave any information of their having happened. This is indistinguishable from their not having happened at all. The second law of thermodynamics is then reduced to a tautology: the only transformations that can be seen are those where entropy does not decrease. However, typicality arguments seem to prevent this argument to be used as a complete solution to the arrow-of-time dilemma: it might still be necessary to postulate a low entropy initial state for the system under consideration.
I acknowledge a flaw in the paper "A quantum solution to the arrow of time dilemma": as pointed out by Jennings and Rudolph, (classical) mutual information is not an appropriate measure of information. This can be traced back to the quantum description underlying my analysis, where quantum mutual information is the appropriate measure of information. The core argument of my paper (summarized in its abstract) is not affected by this flaw. Nonetheless, I point out that such argument may not be adequate to account for all phenomena: it seems necessary to separately postulate a low entropy initial state.
The arrow-of-time dilemma states that the laws of physics are invariant for time inversion, whereas the familiar phenomena we see everyday are not (i.e., entropy increases). I show that, within a quantum mechanical framework, all phenomena which leave a trail of information behind (and hence can be studied by physics) are those where entropy necessarily increases or remains constant. All phenomena where the entropy decreases must not leave any information of their having happened. This situation is completely indistinguishable from their not having happened at all. In the light of this observation, the second law of thermodynamics is reduced to a mere tautology: physics cannot study those processes where entropy has decreased, even if they were commonplace.