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The Impossibility of Large-scale Retrocausal Signalling

Remi Cornwall

Published Sep 1, 2017• 0 citations
OpenAlex

Abstract

Following an earlier paper, an argument is presented that sets up a causality paradox with signals that are claimed to be retrocausal. This is not to be dismissive of claims of retrocausality over small scales by the mechanism of advanced and retarded waves, just that it is not possible over timescales greater than the energy-time uncertainty relationship.

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It has become increasingly apparent that a number of perplexing issues associated with the interpretation of quantum mechanics are more easily resolved once the notion of retrocausality is introduced. The aim here is to list and discuss various examples where a clear explanation has become available via this approach. In so doing, the intention is to highlight that this direction of research deserves more attention than it presently receives.

arXiv:1706.02290•AIP conference proceedings•Jan 1, 2017•20 citations

The Case for Advance Wave Causality

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Abstract: We seek to strengthen the hypothesis of time reversal of cause and effect, or the bipolar causal nature of advanced and retarded waves. The hypothesis is not directly testable, at least with existing technology, so the argument is based on a priori reasoning. It provides a basis for rationalizing entanglement and for the Wheeler-Feynman absorber theory. Alternative hypotheses are given and compared to show justification. KeyWords: advance wave; retrocausation; causal time reversal; Occam’s razor; entanglement; Wheeler-Feynman absorber

Journal of Scientific Exploration•Mar 15, 2019•5 citations

Realism and causality. I. Pilot wave and retrocausal models as possible facilitators

Eliahu Cohen, Marina Cortês, Avshalom C. Elitzur +1 more

Of all basic principles of classical physics, realism should arguably be the last to be given up when seeking a better interpretation of quantum mechanics. We examine the de Broglie-Bohm pilot wave theory as a well-developed example of a realistic theory. We present three challenges to a naive reading of pilot wave theory, each based on a system of several entangled particles. With the help of a coarse graining of pilot wave theory into a discrete system, we show how these challenges can be answered. However, this comes with a cost. In the description of individual systems, particles appear to scatter off empty branches of the wave function as if they were particles and conversely travel through particles as if they were waves. More generally, the ``particles'' of pilot wave theory are led by the guidance equation to move in ways no classical particle would, involving apparent violations of the principles of inertia and momentum conservation. We next argue that the aforementioned cost can be avoided within a retrocausal model. In the proposed version of the pilot wave theory, the particle is guided by a combination of advanced and retarded waves. The resulting account for quantum physics seems to have greater heuristic power, demands less damage to intuition, and moreover provides some general hints regarding spacetime and causality. This is the first of two papers. In the second [E. Cohen, M. Cort\^es, A. C. Elitzur, and L. Smolin, Realism and causality. II. Retrocausality in energetic causal sets, Phys. Rev. D 102, 124028 (2020).], we show that, in the context of an explicit model, retrocausality, with respect to an effective, emergent spacetime metric, can coexist with a strict irreversibility of causal processes.

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A Common Fallacy in Quantum Mechanics: Why Delayed Choice Experiments do NOT imply Retrocausality

David Ellerman

•Jan 1, 2011•2 citations

Entropy and Information Transmission in Causation and Retrocausation

Garret Moddel

Although experimental evidence for retrocausation exists, there are clearly subtleties to the phenomenon. The bilking paradox, in which one intervenes to eliminate a subsequent cause after a preceding effect has occurred, appears on the surface to show that retrocausation is logically impossible. In a previous paper, the second law of thermodynamics was invoked to show that the entropy in each process of a psi interaction (presentience, telepathy, remote perception, and psychokinesis) cannot decrease, prohibiting psi processes in which signals condense from background fluctuations. Here it is shown, perhaps contrary to one’s intuition, that reversible processes cannot be influenced through retrocausation, but irreversible processes can. The increase in thermodynamic entropy in irreversible processes — which are generally described by Newtonian mechanics but not Lagrangian dynamics and Hamilton’s Principle — is required for causation. Thermodynamically reversible processes cannot be causal and hence also cannot be retrocausal. The role of entropy in psi interactions is extended by using the bilking paradox to consider information transmission in retroactive psychokinesis (PK). PK efficiency, ηPK, is defined. A prediction of the analysis is that ηPK ⩽ H/H0, where H is the information uncertainty or entropy in the retro‐PK agent’s knowledge of the event that is to be influenced retrocausally. The information entropy can provide the necessary ingredient for non‐reversibility, and hence retrocausation. Noise and bandwidth limitations in the communication to the agent of the outcome of the event increase the maximum PK efficiency. Avoidance of the bilking paradox does not bar a subject from using the premonition of an event to prevent it from occurring. The necessity for large information entropy, which is the expected value of the surprisal, is likely to be essential for any successful PK process, not just retro‐PK processes. Hence uncertainty in the communication process appears to be a necessary component of retrocausation in particular, and of PK in general.

AIP conference proceedings•Jan 1, 2006•3 citations

Special relativity not implying retrocausality

J. Domínguez-Montes, E. L. Eisman

Physics Essays•Aug 16, 2010•1 citation
Following an earlier paper, an argument is presented that sets up a causality paradox with signals that are claimed to be retrocausal. This is not to be dismissive of claims of retrocausality over small scales by the mechanism of advanced and retarded waves, just that it is not possible over timescales greater than the energy-time uncertainty relationship.
Abstract: We seek to strengthen the hypothesis of time reversal of cause and effect, or the bipolar causal nature of advanced and retarded waves. The hypothesis is not directly testable, at least with existing technology, so the argument is based on a priori reasoning. It provides a basis for rationalizing entanglement and for the Wheeler-Feynman absorber theory. Alternative hypotheses are given and compared to show justification. KeyWords: advance wave; retrocausation; causal time reversal; Occam’s razor; entanglement; Wheeler-Feynman absorber
Of all basic principles of classical physics, realism should arguably be the last to be given up when seeking a better interpretation of quantum mechanics. We examine the de Broglie-Bohm pilot wave theory as a well-developed example of a realistic theory. We present three challenges to a naive reading of pilot wave theory, each based on a system of several entangled particles. With the help of a coarse graining of pilot wave theory into a discrete system, we show how these challenges can be answered. However, this comes with a cost. In the description of individual systems, particles appear to scatter off empty branches of the wave function as if they were particles and conversely travel through particles as if they were waves. More generally, the ``particles'' of pilot wave theory are led by the guidance equation to move in ways no classical particle would, involving apparent violations of the principles of inertia and momentum conservation. We next argue that the aforementioned cost can be avoided within a retrocausal model. In the proposed version of the pilot wave theory, the particle is guided by a combination of advanced and retarded waves. The resulting account for quantum physics seems to have greater heuristic power, demands less damage to intuition, and moreover provides some general hints regarding spacetime and causality. This is the first of two papers. In the second [E. Cohen, M. Cort\^es, A. C. Elitzur, and L. Smolin, Realism and causality. II. Retrocausality in energetic causal sets, Phys. Rev. D 102, 124028 (2020).], we show that, in the context of an explicit model, retrocausality, with respect to an effective, emergent spacetime metric, can coexist with a strict irreversibility of causal processes.
Although experimental evidence for retrocausation exists, there are clearly subtleties to the phenomenon. The bilking paradox, in which one intervenes to eliminate a subsequent cause after a preceding effect has occurred, appears on the surface to show that retrocausation is logically impossible. In a previous paper, the second law of thermodynamics was invoked to show that the entropy in each process of a psi interaction (presentience, telepathy, remote perception, and psychokinesis) cannot decrease, prohibiting psi processes in which signals condense from background fluctuations. Here it is shown, perhaps contrary to one’s intuition, that reversible processes cannot be influenced through retrocausation, but irreversible processes can. The increase in thermodynamic entropy in irreversible processes — which are generally described by Newtonian mechanics but not Lagrangian dynamics and Hamilton’s Principle — is required for causation. Thermodynamically reversible processes cannot be causal and hence also cannot be retrocausal. The role of entropy in psi interactions is extended by using the bilking paradox to consider information transmission in retroactive psychokinesis (PK). PK efficiency, ηPK, is defined. A prediction of the analysis is that ηPK ⩽ H/H0, where H is the information uncertainty or entropy in the retro‐PK agent’s knowledge of the event that is to be influenced retrocausally. The information entropy can provide the necessary ingredient for non‐reversibility, and hence retrocausation. Noise and bandwidth limitations in the communication to the agent of the outcome of the event increase the maximum PK efficiency. Avoidance of the bilking paradox does not bar a subject from using the premonition of an event to prevent it from occurring. The necessity for large information entropy, which is the expected value of the surprisal, is likely to be essential for any successful PK process, not just retro‐PK processes. Hence uncertainty in the communication process appears to be a necessary component of retrocausation in particular, and of PK in general.