Abstract In this chapter we discuss the Einstein Podolsky Rosen theorem and its strong relation with Bell’s theorem. The central role played by the concept of beable introduced by Bell is emphasized. In particular we stress that beables involved in EPR and Bell theorems are not limited to hidden supplementary variables (e.g., like in the de Broglie-Bohm (dBB) pilot-wave theory) but also include the wave function. In full agreement with Bell this allows us the reformulate the EPR and Bell results as strong theorems concerning nonlocality for quantum mechanics itself and not only for hidden-variables approaches as it is often mistakenly assumed. Furthermore, we clarify some repeated ambiguities concerning ‘local-realism’ and emphasize that neither realism nor determinism nor counterfactual definiteness are prerequisites of EPR and Bell theorems.
Abstract In this chapter we discuss the Einstein Podolsky Rosen theorem and its strong relation with Bell’s theorem. The central role played by the concept of beable introduced by Bell is emphasized. In particular we stress that beables involved in EPR and Bell theorems are not limited to hidden supplementary variables (e.g., like in the de Broglie-Bohm (dBB) pilot-wave theory) but also include the wave function. In full agreement with Bell this allows us the reformulate the EPR and Bell results as strong theorems concerning nonlocality for quantum mechanics itself and not only for hidden-variables approaches as it is often mistakenly assumed. Furthermore, we clarify some repeated ambiguities concerning ‘local-realism’ and emphasize that neither realism nor determinism nor counterfactual definiteness are prerequisites of EPR and Bell theorems.
In this chapter we discuss the Einstein Podolsky Rosen theorem and its strong relation with Bell's theorem. The central role played by the concept of beable introduced by Bell is emphasized. In particular we stress that beables involved in EPR and Bell theorems are not limited to hidden supplementary variables (e.g., like in the de Broglie-Bohm (dBB) pilot-wave theory) but also include the wave function. In full agreement with Bell this allows us the reformulate the EPR and Bell results as strong theorems concerning nonlocality for quantum mechanics itself and not only for hidden-variables approaches as it is often mistakenly assumed. Furthermore, we clarify some repeated ambiguities concerning `local-realism' and emphasize that neither realism nor determinism nor counterfactual definiteness are prerequisites of EPR and Bell theorems.
Quantum mechanics, despite its extraordinary success in describing microscopic phenomena, continues to raise foundational questions concerning measurement, nonlocality, and the nature of physical reality. These issues are exemplified by the Einstein-Podolsky-Rosen (EPR) paradox and the Bell inequality, which contrast quantum correlations with classical notions of locality and realism. In this work, we critically examine the assumptions underlying Bell’s theorem in light of the incompatible and contextual nature of quantum observables. We show that Bell’s constraint on simultaneous definite values for incompatible observables, together with the assumption of hidden variables, is not applicable to quantum mechanics itself, which is inherently nonclassical and contextual. When measurement is modeled as a local system-environment interaction within the framework of quantum decoherence, the resulting dynamics remain entirely local and unitary in the EPR scenario. Decoherence naturally selects pointer states and suppresses interference, giving rise to the appearance of wavefunction collapse consistent with quantum predictions. Importantly, the Bell correlations obtained in this framework reproduce the standard quantum results and are independent of both system-bath and inter-bath interactions, which affect only the rate of decoherence. Our analysis suggests that, in the EPR scenario, quantum mechanics can be both local and realistic when the wavefunction is treated as an ontic description of reality within the decoherence framework, offering a potential route toward a locally realistic quantum theory aligned with Einstein’s vision. This work contributes to a more rigorous foundation for quantum mechanics, providing insights that can accelerate progress in quantum computing and nanoenergy harvesting.
Most physicists agree that the Einstein–Podolsky–Rosen–Bell paradox exemplifies much of the strange behavior of quantum mechanics, but argument persists about what assumptions underlie the paradox. To clarify what the debate is about, we employ a simple and well-known thought experiment involving two correlated photons to help us focus on the logical assumptions needed to construct the EPR and Bell arguments. The view presented in this paper is that the minimal assumptions behind Bell’s inequality are locality and counterfactual definiteness but not scientific realism, determinism, or hidden variables as are often suggested. We further examine the resulting constraints on physical theory with an illustration from the many-worlds interpretation of quantum mechanics—an interpretation that we argue is deterministic, local, and realist but that nonetheless violates the Bell inequality.
John Stewart Bell’s famous theorem is widely regarded as one of the most important developments in the foundations of physics. Yet even as we approach the 50th anniversary of Bell’s discovery, its meaning and implications remain controversial. Many workers assert that Bell’s theorem refutes the possibility suggested by Einstein, Podolsky, and Rosen (EPR) of supplementing ordinary quantum theory with “hidden” variables that might restore determinism and/or some notion of an observer-independent reality. But Bell himself interpreted the theorem very differently—as establishing an “essential conflict” between the well-tested empirical predictions of quantum theory and relativistic local causality. Our goal is to make Bell’s own views more widely known and to explain Bell’s little-known formulation of the concept of relativistic local causality on which his theorem rests. We also show precisely how Bell’s formulation of local causality can be used to derive an empirically testable Bell-type inequality and to recapitulate the EPR argument.
In this paper, we show that Erwin Schroedinger's generalization of the Einstein Podolsky Rosen argument can be connected to certain mathematical theorems - Gleason's and also Kochen and Specker's - in a manner analogous to the relation of EPR itself with Bell's theorem. In both cases, the conclusion is quantum nonlocality, as we discuss. The "Schroedinger nonlocality" proofs share some features with the Greenberger, Horne, and Zeilinger quantum-nonlocality work, yet also differ in significant ways. For clarity and completeness, we begin with a detailed discussion of the topic of hidden variable theorems. We argue, in agreement with John S. Bell, that 'impossibility' does not follow.
Negating the classical/quantum divide in line with Bell's hidden-variable ideas, we resolve Bell's ‘action-at-a-distance' dilemma in accord with his hopes. We identify the resultant theory as clear local realism (CLR), the union of Bohr's ‘measurement' insight, Einstein locality and Bell beables. Our method follows: (i) consistent with Bohr's insight, we replace EPR's elements of physical reality with Bell's beables; (ii) we let Bell's beable λ denote a pristine particle's total angular momentum; (iii) validating Malus' Law in our quantum-compatible equivalence relations, we deliver the hopes of Bell and Einstein for a simple constructive model of EPRB; (iv) we then derive the correct results for CHSH and Mermin's version of GHZ; (v) we thus justify EPR's belief that additional variables would bring locality and causality to QM. In short, advancing Bell's ideas in line with his expectations: we amend EPR, resolve Bell's dilemma, negate nonlocality, endorse Einstein's locally-causal Lorentz-invariant worldview, demystify the classical/quantum divide, etc. CLR: clear via Bohr's insight, local via Einstein locality, realistic via Bell beables.