Two typical entanglements will be shown to stand on opposite sides on the issue of \emph{instrumental realism}, the issue of whether (as for EPR in the original form or EPRB, Bohm's versions using spin) or not (as for GHZ) observables have values that preexist measurement. Instrumental realism in the EPR context helps us prove that in some special circumstances, one can get simultaneous knowledge of two conjugate quantities, which in particular make sense together. This shatters the axiomatic presentation of Quantum Mechanics. This simultaneous knowledge of two conjugate quantities elaborates on 1935 work by Schr{ö}dinger, hence the name, \emph{Schr{ö}dinger Unorthodoxy Theorem}, given to the second main result that is easily deduced from the result on instrumental realism. Once the axiomatic edifice of Quantum Mechanics is broken, we can let go the completeness of the wave function as suggested in EPR, and hold fast on locality. The EPR paper of mid-1935 gets here contrasted, from a new point of view, with a 1936 text where Einstein avoids using counterfactuals. Counterfactuals get a precise definition and the corresponding concept is used all along, but may be new under an old name. We provide a short critical review of Bell's 1964 paper. Then, a small modification of arguments for the Schr{ö}dinger Unorthodoxy Theorem will let appear a simple conservation law, combined with the Malus Law, as the origin of the correlation in Bell's version of EPRB: this is our third main result. As the fourth main result, a last use of the concept of counterfactual yields the decay of geometry at small enough scale. This opens a new world of interpretation of aspects of Quantum Mechanics, aspects that range from measurement and the need of classical physics to views on what realism should mean in microphysics.
Two typical entanglements will be shown to stand on opposite sides on the issue of \emph{instrumental realism}, the issue of whether (as for EPR in the original form or EPRB, Bohm's versions using spin) or not (as for GHZ) observables have values that preexist measurement. Instrumental realism in the EPR context helps us prove that in some special circumstances, one can get simultaneous knowledge of two conjugate quantities, which in particular make sense together. This shatters the axiomatic presentation of Quantum Mechanics. This simultaneous knowledge of two conjugate quantities elaborates on 1935 work by Schr{ö}dinger, hence the name, \emph{Schr{ö}dinger Unorthodoxy Theorem}, given to the second main result that is easily deduced from the result on instrumental realism. Once the axiomatic edifice of Quantum Mechanics is broken, we can let go the completeness of the wave function as suggested in EPR, and hold fast on locality. The EPR paper of mid-1935 gets here contrasted, from a new point of view, with a 1936 text where Einstein avoids using counterfactuals. Counterfactuals get a precise definition and the corresponding concept is used all along, but may be new under an old name. We provide a short critical review of Bell's 1964 paper. Then, a small modification of arguments for the Schr{ö}dinger Unorthodoxy Theorem will let appear a simple conservation law, combined with the Malus Law, as the origin of the correlation in Bell's version of EPRB: this is our third main result. As the fourth main result, a last use of the concept of counterfactual yields the decay of geometry at small enough scale. This opens a new world of interpretation of aspects of Quantum Mechanics, aspects that range from measurement and the need of classical physics to views on what realism should mean in microphysics.
The Einstein-Podolsky-Rosen (EPR) paradox gives an argument for the incompleteness of quantum mechanics based on a plausible criterion for reality, as well as the assumption of locality. A general view is that the argument is compromised, because EPR's premises are falsified by Greenberger-Horne-Zeilinger (GHZ) and Bell experiments. In this paper, we present an EPR argument based on premises not falsified by these experiments. First, we consider macroscopic EPR-Bohm, Bell, and GHZ experiments using spins ${\stackrel{\ifmmode \hat{}\else \^{}\fi{}}{S}}_{\ensuremath{\theta}}$ defined by two macroscopically distinct states. The analyzers that realize the unitary operations ${U}_{\ensuremath{\theta}}$ determining the measurement settings $\ensuremath{\theta}$ are nonlinear devices creating macroscopic superposition states. We note two definitions of macroscopic realism (MR). For a system with two macroscopically distinct states available to it, MR posits a predetermined outcome for the measurement ${\stackrel{\ifmmode \hat{}\else \^{}\fi{}}{S}}_{\ensuremath{\theta}}$ distinguishing between the states. Deterministic macroscopic realism assumes MR for the system defined prior to the interaction ${U}_{\ensuremath{\theta}}$ being carried out but is falsifiable by the macroscopic Bell and GHZ proposals. Motivated by arguments to uphold MR (without resorting to decoherence), as well as no-signaling and the properties of a meter, we define a set of premises referred to as weak macroscopic realism (wMR). Weak macroscopic realism (wMR) posits MR for the system after ${U}_{\ensuremath{\theta}}$, at the time tf---when the system is prepared with respect to the measurement basis, ready for a ``pointer'' measurement and readout. For this system, wMR posits that the outcome of ${\stackrel{\ifmmode \hat{}\else \^{}\fi{}}{S}}_{\ensuremath{\theta}}$ is determined and not changed by interactions that might subsequently occur at a remote system B. The premise wMR also posits a weaker version of EPR's criterion for reality. Importantly, we show that the GHZ and Bell predictions are consistent with wMR. Yet, an EPR paradox arises for a macroscopic EPR-Bohm state, based on wMR. As considered by Schr\"odinger, it is possible to measure two complementary spins of system A simultaneously, ``one by direct, the other by indirect measurement'': If we assume wMR, then once both settings are fixed, the outcomes of the two spins are both determined. We revisit the original EPR paradox and find a similar result: An EPR argument can be based on a set of premises, weak local realism, which we show are not falsifiable by GHZ or Bell experiments.
An open letter to Bellians and the Annals of Physics' Editors re -- it's a proven scientific fact: a violation of local realism has been demonstrated theoretically and experimentally -- after AoP (2016:67). EPR (1935) famously argue that additional variables will bring locality and causality to QM's completion; we show that they are right. Even more famously, Bell (1964) cried ‘impossible' against such variables; we give the shortest possible refutation of his claims. With EPR-based variables (and without QM), an old thought-experiment delivers a commonsensical locally-causal account of EPRB and GHZ in 3-space. We then name the flaw in Bell's theorem – Bell's error -- Bell's 1964:(14a) ≠ Bell's 1964:(14b) under EPRB. Thus, given Bell's (1988:88) gloss on a snippet of von Neumann's work, ‘There's nothing to Bell's theorem -- nor variants like CHSH (1969), Mermin (1990), Peres (1995) -- it's not just flawed, it's silly; not merely false but foolish.' In short, we show that the whole Bellian canon -- with its no-name brand of local realism -- is all of those, and misleading too. Under EPR, mixing common-sense with undergrad math/physics in the classical way so favored by Einstein, we interpret QM locally and realistically. We thus define a new brand of local realism -- CLR, commonsense local realism -- the union of local-causality (no causal influence propagates superluminally) and physical-realism (some physical properties change interactively). Long may EPR rule OK we say.
The Einstein-Podolsky-Rosen (EPR) paradox gives an argument for the incompleteness of quantum mechanics based on the premises of local realism. A general view is that the argument is compromised, because EPR's premises are falsified by Greenberger-Horne-Zeilinger (GHZ) and Bell experiments. In this paper, we present an EPR argument based on premises not falsifiable by these experiments. We propose macroscopic EPR and GHZ experiments using spins Sθ defined by two macroscopically distinct states. The analyzers that realize the unitary operations Uθ determining the measurement settings θ are devices that create macroscopic superposition states. For a system with two macroscopically distinct states available, macroscopic realism (MR) posits a predetermined outcome for a measurement Sθ distinguishing between the states. Deterministic macroscopic realism (dMR) posits MR for the system prior to the interaction Uθ. Weak macroscopic realism (wMR) posits MR for the system after Uθ, at the time tf (when the system is prepared for a final "pointer" measurement), the outcome of Sθ not being changed by interactions that might occur at a remote system B. The premise also posits that if the outcome for SθA of a system A can be predicted by a pointer measurement on a system B defined after the interaction fixing the setting at B, then the outcome for SθA is determined at this time. The GHZ predictions negate dMR but are consistent with wMR. Yet, an EPR paradox arises based on wMR for the set-up proposed by Schrödinger, where one measures two complementary spins simultaneously, "one by direct, the other by indirect" measurement. We revisit the original EPR paradox and find similarly that an EPR argument can be based on a weak form of local realism not falsifiable by GHZ or Bell tests.
The EPR controversy between Albert Einstein and Niels Bohr about the completeness of the quantum mechanics is one of the most essential contemporary debates in physics with respect to the issue of realism. Initially considered as a though-experiment, the EPR paradox was meant to evidence the inadequacy of quantum mechanics with respect to the traditional leading principle of physics such as locality, independence of the system elements of reality with respect to the observer or semantic reference of theories to elements of the reality in itself. Bell’s mathematical inquiry opened the possibility to empirically discriminate between the view of Bohr and Einstein through the so-called Bell’s inequalities. Based on these inequalities, the experimental test provided in particular by the work of Alain Aspect settled the debate in favor of Bohr and the completeness of quantum mechanics. The previously evident assumption that physical theories are describing the reality in it-self can thus be questioned. Several approaches have been proposed to face that challenge, such as the orthodox quantum physics formulation coupled with the interpretation of Bernard d’Espagnat , the non-local theory of De Broglie-Bohm or the quantum mechanics approach with extended probability of James B. Hartle . In this paper, we consider the idea according to which the field of experiments and measurements on quantum systems is a research context where several epistemic values traditionally leading the scientific activity are in conflict. Instead of conceiving the transition from classical to quantum physics along Thomas Kuhns’ theory of revolutionary paradigm change , characterized by a strong incommensurability between the old and the new approaches, we argue that this epistemological shift could be rationally understood as an incremental evolution of the epistemic values leading scientific activity. As the analysis in this paper aims to show, such a rational reconstruction shows a process of gradual change, where core epistemic values are maintained, while others are broadened to account for the new scientific approaches. The settling of the EPR controversy could be understood as the indication that the previously assumed epistemic values cannot be consistently held together in the quantum context. The values of logical consistency and empirical adequacy remained universally shared, but the controversy leads to question the other traditionally admitted principles, such as the locality, the requirement of semantic references to the reality in itself and the independence of experimental results with respect to the observer, all tightly connected with the realistic conceptions of the world. This first part of the paper characterizes the selected contemporary approaches in quantum context with respect to the modification of the epistemic principles they adopt to restore their consistency. While the de Broglie-Bohm theory explicitly follows the requirement of referring to the reality in itself at the expense of the locality principle, the approaches of d’Espagnat and of Hartle give priority to the values of theoretical framework simplicity and predictive power. In the case of d’Espagnat, the descriptive purpose of the scientific activity remains, but only in a weak objectivity perspective, restricted to the “empirical reality” in which the observer is involved. In the case of Hartle, the extended probability formulation of quantum mechanics is conceived as “an extension of familiar probability theory that incorporates negative probabilities”6, which relies on the Bayesian conception of “probabilities as instruction for betting” (negative probability is thus associated to the instruction “don’t bet”). In a second part, the paper uses this reconstruction of the various theories in order to address the epistemic status of the principles of descriptive power and of independence of the observed system with respect to the observer. In particular, our analysis aims to assess if a reference to the observer is part of the reality description or if such reference is avoidable. This is of prior interest in exploring the main characteristics of a realistic approach that would be applicable in the context of experiments and measurements on quantum systems. In that perspective, we argue that the direct holistic realism, developed by Hilary Putnam in The Threefold Cord , could be a promising intermediate option between a classical realism, which assumes that theoretical structures are describing the reality in it-self, and a more instrumentalist view, focusing mainly on the modeling of the empirical reality as a result of experimental operations while rejecting access to the reality in itself.
The Einstein-Podolsky-Rosen (EPR) paradox was presented as an argument that quantum mechanics is an incomplete description of physical reality. However, the premises on which the argument is based are falsifiable by Bell experiments. In this paper, we examine the EPR paradox from the perspective of Schrodinger's reply to EPR. Schrodinger pointed out that the correlated states of the paradox enable the simultaneous measurement of x^ and p^, one by direct, the other by indirect measurement. Schrodinger's analysis takes on a timely importance because a recent experiment realizes these correlations for macroscopic atomic systems. Different to the original argument, Schrodinger's analysis applies to the experiment at the time when the measurement settings have been fixed. In this context, a subset of local realistic assumptions (not negated by Bell's theorem) implies that x and p are simultaneously precisely defined. Hence, an alternative EPR argument can be presented that quantum mechanics is incomplete, based on a set of (arguably) nonfalsifiable premises. As systems are amplified, macroscopic realism can be invoked, and the premises are referred to as weak macroscopic realism (wMR). In this paper, we propose a realization of Schrodinger's gedanken experiment where field quadrature phase amplitudes X^ and P^ replace position and momentum. Assuming wMR, we derive a criterion for the incompleteness of quantum mechanics, showing that the criterion is feasible for current experiments. Questions raised by Schrodinger are resolved. By performing simulations based on an objective-field (Q-based) model for quantum mechanics, we illustrate the emergence on amplification of simultaneous predetermined values for X^ and P^. The values can be regarded as weak elements of reality, along the lines of Bell's macroscopic beables.
This open letter challenges Annals of Physics' Editors and Bell's supporters on this front: in the context of Bell's theorem -- after AoP (2016:67) -- ‘it's a proven scientific fact that a violation of local realism has been demonstrated theoretically and experimentally.' We show that such claims under the Bellian canon are curtailed by its foundation on a naive realism that is known to be false; ie, under Bohr's old insight (in our terms), a test may disturb the tested system. Further: (i) We define a general all-embracing local realism -- CLR, commonsense local realism -- the union of local-causality (no causal influence propagates superluminally) and physical-realism (some physical properties change interactively). (ii) Under CLR, with EPR-based variables (and without QM), a thought-experiment delivers a local-realistic account of EPRB and GHZ in 3-space. (iii) Under EPR, mixing common-sense with undergrad math/physics in the classical way so favored by Einstein, we interpret QM locally and realistically. (iv) We find the flaw in Bell's theorem: Bell's 1964:(14a) ≠ Bell's 1964:(14b) under EPRB. (v) EPR (1935) famously argue that additional variables will bring locality and causality to QM's completion; we show that they are right. (vi) Even more famously, Bell (1964) cried ‘impossible' against such variables; we give the shortest possible refutation of his claim. (vii) Using Bell's (1988:88) moot gloss on a fragment of von Neumann's work, we conclude: ‘There's nothing to Bell's theorem -- nor Bellian variants like CHSH (1969), Mermin (1990), Peres (1995); nor Bellian endorsements like those by Bricmont, du Sautoy, Goldstein et al., Maudlin, Norsen, Shimony -- it's not just flawed, it's silly; its assumptions nonsense; it's not merely false but foolish' and misleading. (viii) Our results accord with common-sense, QM, Einstein's principles, EPR's belief and Bell's hopes and expectations.