Accommodating Retrocausality with Free Will

Retrocausal models of quantum mechanics add further weight to the conflict between causality and the possible existence of free will. We analyze a simple closed causal loop ensuing from the interaction between two systems with opposing thermodynamic time arrows, such that each system can forecast fu...

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Main Authors: Yakir Aharonov, Eliahu Cohen, Tomer Shushi
Format: Article
Language:English
Published: Quanta 2016-01-01
Series:Quanta
Online Access:http://quanta.ws/ojs/index.php/quanta/article/view/44
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author Yakir Aharonov
Eliahu Cohen
Tomer Shushi
author_facet Yakir Aharonov
Eliahu Cohen
Tomer Shushi
author_sort Yakir Aharonov
collection DOAJ
description Retrocausal models of quantum mechanics add further weight to the conflict between causality and the possible existence of free will. We analyze a simple closed causal loop ensuing from the interaction between two systems with opposing thermodynamic time arrows, such that each system can forecast future events for the other. The loop is avoided by the fact that the choice to abort an event thus forecasted leads to the destruction of the forecaster's past. Physical law therefore enables prophecy of future events only as long as this prophecy is not revealed to a free agent who can otherwise render it false. This resolution is demonstrated on an earlier finding derived from the two-state vector formalism, where a weak measurement's outcome anticipates a future choice, yet this anticipation becomes apparent only after the choice has been actually made. To quantify this assertion, weak information is described in terms of Fisher information. We conclude that an already existing future does not exclude free will nor invoke causal paradoxes. On the quantum level, particles can be thought of as weakly interacting according to their past and future states, but causality remains intact as long as the future is masked by quantum indeterminism. Quanta 2016; 5: 53–60.
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spelling doaj.art-7148065de4c9441da002675c12d4e7f42022-12-21T22:24:34ZengQuantaQuanta1314-73742016-01-0151536010.12743/quanta.v5i1.4423Accommodating Retrocausality with Free WillYakir Aharonov0Eliahu Cohen1Tomer Shushi2Tel Aviv UniversityTel Aviv UniversityUniversity of HaifaRetrocausal models of quantum mechanics add further weight to the conflict between causality and the possible existence of free will. We analyze a simple closed causal loop ensuing from the interaction between two systems with opposing thermodynamic time arrows, such that each system can forecast future events for the other. The loop is avoided by the fact that the choice to abort an event thus forecasted leads to the destruction of the forecaster's past. Physical law therefore enables prophecy of future events only as long as this prophecy is not revealed to a free agent who can otherwise render it false. This resolution is demonstrated on an earlier finding derived from the two-state vector formalism, where a weak measurement's outcome anticipates a future choice, yet this anticipation becomes apparent only after the choice has been actually made. To quantify this assertion, weak information is described in terms of Fisher information. We conclude that an already existing future does not exclude free will nor invoke causal paradoxes. On the quantum level, particles can be thought of as weakly interacting according to their past and future states, but causality remains intact as long as the future is masked by quantum indeterminism. Quanta 2016; 5: 53–60.http://quanta.ws/ojs/index.php/quanta/article/view/44
spellingShingle Yakir Aharonov
Eliahu Cohen
Tomer Shushi
Accommodating Retrocausality with Free Will
Quanta
title Accommodating Retrocausality with Free Will
title_full Accommodating Retrocausality with Free Will
title_fullStr Accommodating Retrocausality with Free Will
title_full_unstemmed Accommodating Retrocausality with Free Will
title_short Accommodating Retrocausality with Free Will
title_sort accommodating retrocausality with free will
url http://quanta.ws/ojs/index.php/quanta/article/view/44
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AT eliahucohen accommodatingretrocausalitywithfreewill
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