scholarly journals Nonlocality in Bell’s Theorem, in Bohm’s Theory, and in Many Interacting Worlds Theorising

Entropy ◽  
2018 ◽  
Vol 20 (8) ◽  
pp. 567 ◽  
Author(s):  
Mojtaba Ghadimi ◽  
Michael Hall ◽  
Howard Wiseman
Keyword(s):  
Quantum Mechanics ◽  
Quantum Theory ◽  
Bohmian Mechanics ◽  
Bell’S Theorem ◽  
Bell's Theorem ◽  
Significant Progress ◽  
Technical Problems ◽  
New Approach ◽  
Weak Notion ◽  
Bohm’S Theory

“Locality” is a fraught word, even within the restricted context of Bell’s theorem. As one of us has argued elsewhere, that is partly because Bell himself used the word with different meanings at different stages in his career. The original, weaker, meaning for locality was in his 1964 theorem: that the choice of setting by one party could never affect the outcome of a measurement performed by a distant second party. The epitome of a quantum theory violating this weak notion of locality (and hence exhibiting a strong form of nonlocality) is Bohmian mechanics. Recently, a new approach to quantum mechanics, inspired by Bohmian mechanics, has been proposed: Many Interacting Worlds. While it is conceptually clear how the interaction between worlds can enable this strong nonlocality, technical problems in the theory have thus far prevented a proof by simulation. Here we report significant progress in tackling one of the most basic difficulties that needs to be overcome: correctly modelling wavefunctions with nodes.

Bell’s theorem

2018 ◽  
Author(s):  
Arthur Fine
Keyword(s):  
Quantum Mechanics ◽  
Quantum Theory ◽  
Experimental Tests ◽  
Bell Inequalities ◽  
Bell’S Theorem ◽  
Bell's Theorem ◽  
Bell Theorem ◽  
System Of Inequalities ◽  
Action At A Distance ◽  
High Degree

Bell’s theorem is concerned with the outcomes of a special type of ‘correlation experiment’ in quantum mechanics. It shows that under certain conditions these outcomes would be restricted by a system of inequalities (the ‘Bell inequalities’) that contradict the predictions of quantum mechanics. Various experimental tests confirm the quantum predictions to a high degree and hence violate the Bell inequalities. Although these tests contain loopholes due to experimental inefficiencies, they do suggest that the assumptions behind the Bell inequalities are incompatible not only with quantum theory but also with nature. A central assumption used to derive the Bell inequalities is a species of no-action-at-a-distance, called ‘locality’: roughly, that the outcomes in one wing of the experiment cannot immediately be affected by measurements performed in another wing (spatially distant from the first). For this reason the Bell theorem is sometimes cited as showing that locality is incompatible with the quantum theory, and the experimental tests as demonstrating that nature is nonlocal. These claims have been contested.

scholarly journals Knowledge of Quantum Hidden Variables Enables Backwards-In-Time Signaling

2021 ◽  
Vol 11 (10) ◽  
pp. 4477
Author(s):  
Avishy Carmi ◽  
Eliahu Cohen ◽  
Lorenzo Maccone ◽  
Hrvoje Nikolić
Keyword(s):  
Quantum Mechanics ◽  
Reference Frame ◽  
Hidden Variables ◽  
Bohmian Mechanics ◽  
The State ◽  
Bell’S Theorem ◽  
Relativity Theory ◽  
Bell's Theorem ◽  
Preferred Reference Frame ◽  
Superluminal Signaling

Bell’s theorem implies that any completion of quantum mechanics which uses hidden variables (that is, preexisting values of all observables) must be nonlocal in the Einstein sense. This customarily indicates that knowledge of the hidden variables would permit superluminal communication. Such superluminal signaling, akin to the existence of a preferred reference frame, is to be expected. However, here we provide a protocol that allows an observer with knowledge of the hidden variables to communicate with her own causal past, without superluminal signaling. That is, such knowledge would contradict causality, irrespectively of the validity of relativity theory. Among the ways we propose for bypassing the paradox there is the possibility of hidden variables that change their values even when the state does not, and that means that signaling backwards in time is prohibited in Bohmian mechanics.

Bell’s theorem and its tests: Proof that nature is superdeterministic—Not random

2020 ◽  
Vol 33 (2) ◽  
pp. 216-218
Author(s):  
Johan Hansson
Keyword(s):  
Quantum Mechanics ◽  
Reference Frames ◽  
Space Time ◽  
Bell’S Theorem ◽  
Quantum Mechanical ◽  
Bell's Theorem ◽  
Fundamental Level ◽  
Global Space ◽  
Mechanical Measurements

By analyzing the same Bell experiment in different reference frames, we show that nature at its fundamental level is superdeterministic, not random, in contrast to what is indicated by orthodox quantum mechanics. Events—including the results of quantum mechanical measurements—in global space-time are fixed prior to measurement.

scholarly journals Classical Logic in the Quantum Context

2020 ◽  
Vol 2 (4) ◽  
pp. 600-616
Author(s):  
Andrea Oldofredi
Keyword(s):  
Quantum Mechanics ◽  
Quantum Theory ◽  
Quantum Logic ◽  
Classical Logic ◽  
Theory Of Measurement ◽  
Propositional Calculus ◽  
Bohmian Mechanics ◽  
Physical Content ◽  
Present Essay ◽  
Classical Propositional Calculus

It is generally accepted that quantum mechanics entails a revision of the classical propositional calculus as a consequence of its physical content. However, the universal claim according to which a new quantum logic is indispensable in order to model the propositions of every quantum theory is challenged. In the present essay, we critically discuss this claim by showing that classical logic can be rehabilitated in a quantum context by taking into account Bohmian mechanics. It will be argued, indeed, that such a theoretical framework provides the necessary conceptual tools to reintroduce a classical logic of experimental propositions by virtue of its clear metaphysical picture and its theory of measurement. More precisely, it will be shown that the rehabilitation of a classical propositional calculus is a consequence of the primitive ontology of the theory, a fact that is not yet sufficiently recognized in the literature concerning Bohmian mechanics. This work aims to fill this gap.

ON THE GEOMETRIZATION OF BOHMIAN MECHANICS: A NEW APPROACH TO QUANTUM GRAVITY

1998 ◽  
Vol 13 (04) ◽  
pp. 677-693 ◽  
Author(s):  
FATIMAH SHOJAI ◽  
MEHDI GOLSHANI
Keyword(s):  
Quantum Theory ◽  
Quantum Gravity ◽  
Classical Limit ◽  
Bohmian Mechanics ◽  
Present Theory ◽  
Space Time ◽  
New Approach ◽  
Theory Of Motion ◽  
Quantum Theory Of Motion ◽  
De Broglie Bohm

In this paper, a new approach to quantum gravity is presented in which the de-Broglie–Bohm quantum theory of motion is geometrized. This way of considering quantum gravity leads automatically to the fact that the quantum effects are contained in the conformal degree of freedom of the space–time metric. The present theory is then applied to the maximally symmetric space–time of cosmology, and it is observed that it is possible to avoid the initial singularity, while at large times the correct classical limit emerges.

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