Abstract Einstein, Podolsky, and Rosen (EPR) argued that quantum mechanics was incomplete. We consider their argument and the physical and philosophical intuitions that motivated it. Among their intuitions was a commitment to real physical properties and to local properties and interactions. For his part, Einstein’s commitment to locality was closely related to how he understood special relativity. We show why the standard collapse formulation of quantum mechanics is flatly incompatible with special relativity. Following Bell, we then see why no physical theory that satisfies EPR’s commonsense and philosophical intuitions can be empirically adequate over quantum phenomena.
Abstract Einstein, Podolsky, and Rosen (EPR) argued that quantum mechanics was incomplete. We consider their argument and the physical and philosophical intuitions that motivated it. Among their intuitions was a commitment to real physical properties and to local properties and interactions. For his part, Einstein’s commitment to locality was closely related to how he understood special relativity. We show why the standard collapse formulation of quantum mechanics is flatly incompatible with special relativity. Following Bell, we then see why no physical theory that satisfies EPR’s commonsense and philosophical intuitions can be empirically adequate over quantum phenomena.
The Einstein–Podolsky–Rosen (EPR) argument was originally posed as a challenge to the completeness of quantum mechanics, rather than its empirical adequacy. While subsequent developments—most notably Bell’s theorem and experimental tests of nonlocal correlations— have constrained classes of hidden-variable theories, they have not resolved the underlying on- tological question raised by EPR: whether the quantum state exhausts physical reality. In this paper, we revisit the EPR criterion of completeness from the perspective of a temporally grounded physical framework, the Temporal Inertia Framework (TIF). We argue that the orig- inal EPR dilemma rests on an implicit assumption that physical reality must be specified on spacelike hypersurfaces, an assumption shared by both EPR and Bohr. By relaxing this assump- tion and allowing physical correlations to arise from shared temporal structure rather than local spatial variables or superluminal influence, one may satisfy the EPR realism criterion without violating relativistic causality or Bell-type constraints. Quantum mechanics is thus interpreted as operationally complete but ontologically incomplete, with quantum indeterminacy emerging from dynamical interactions with a proposed underlying temporal structure.
The Einstein-Podolsky-Rosen (EPR) paradox that argues for the incompleteness of quantum mechanics as a description of physical reality has been put to rest by John Bell’s famous theorem, which inspired numerous experimental tests and brought about further affirmations of quantum reality. Nevertheless, in his writings and public presentations, Richard Feynman never acknowledged the significance of Bell’s contribution to the resolution of the EPR paradox. In this paper, we discuss several variants of the Bell inequalities (including one that was specifically espoused by Feynman), and explore the ways in which they demolish the arguments in favor of local hidden-variable theories. We also examine the roots of Feynman’s attitude toward Bell’s theorem in the context of Feynman’s special perspective on quantum mechanics.
Abstract The 1935 Einstein–Podolsky–Rosen (EPR) paper, “Can Quantum–Mechanical Description of Physical Reality Be Considered Complete?”, stands as a landmark in the foundational debates over quantum mechanics. While the paper has since become one of Einstein’s most cited works, it initially received little attention, and the feature of non-locality, which was central to the argument in the paper, was largely neglected for decades. In this paper, I offer two reasons for this early neglect of non-locality in the immediate aftermath of EPR. First, early responses to the EPR paper defended the completeness of quantum mechanics by reformulating the thought experiment the authors had presented, thereby obscuring the feature of quantum mechanics the authors had wished to highlight. Bohr’s influential reply, for instance, substituted the specific thought experiment presented by EPR with the two-slit experiment, thus suppressing the entanglement between spatially separated systems. A second reason for the marginalization of non-locality was the tendency to see Einstein’s critique of quantum mechanics as proceeding from a commitment to determinism, though this in fact played no role in the EPR paper or in his later writings and correspondence. This paper argues that the failure to recognize non-locality was partly a result of the rhetorical manoeuvring by EPR’s critics, but also to a broader philosophical climate dominated by concerns over determinism, which effectively eclipsed all other conceptual issues, Only with Bell’s theorem in the 1960s did non-locality return as a serious focus of foundational inquiry.
Einstein's 1927 argument for incompleteness A huge literature arose out of the famous ‘EPR’ paper by Einstein, Podolsky and Rosen (1935), entitled ‘Can quantum-mechanical description of physical reality be considered complete?’. The EPR paper argued, on the basis of (among other things) the absence of action at a distance, that quantum theory must be incomplete. It is less well-known that a much simpler argument, leading to the same conclusion, was presented by Einstein eight years earlier in the general discussion at the fifth Solvay conference (pp. 440ff.). Einstein compares and contrasts two views about the nature of the wave function ψ , for the specific case of a single electron. According to view I, ψ represents an ensemble (or ‘cloud’) of electrons, while according to view II, ψ is a complete description of an individual electron. Einstein argues that view II is incompatible with locality, and that to avoid this, in addition to ψ there should exist a localised particle (along the lines of de Broglie's theory). Thus, according to this reasoning, if one assumes locality, then quantum theory (as normally understood today) is incomplete. The conclusion of Einstein's argument in 1927 is the same as that of EPR in 1935, even if the form of the argument is rather different. Einstein considers electrons striking a screen with a small hole that diffracts the electron wave, which on the far side of the screen spreads out uniformly in all directions and strikes a photographic film in the shape of a hemisphere with large radius (see Einstein's figure, p. 440).
From a phenomenological and experimental viewpoint, quantum mechanics is remarkably successful in explaining effects and processes in the microscopic world. Recently, however, a growing body of literature has revisited the theory's own formal foundations, specifically addressing issues of self-consistency and completeness. As a major historical example of these foundational challenges, the Einstein-Podolsky-Rosen (EPR) argument famously claimed that the theory is incomplete. While many valid criticisms and refutations of the EPR logic exist, they generally rely on a combination of technical results and conceptual objections to EPR's interpretive assumptions, thus transcending the plain quantum framework itself. Motivated by these trends of examining the theory's structural limits, here we revisit the EPR argument. Focusing on elements essential to the EPR reasoning, we first analyze general quantum correlations for EPR states: (i) the fact that their observables are always associated with non-commuting operators, and (ii) the nature of the correlated information obtained through measurement. From these two points alone, and relying strictly on the core rules of quantum mechanics, we demonstrate how to overturn the alleged EPR incompleteness without invoking any extraneous propositions. Consequently, we show that the standard formalism alone suffices to resolve such type of skepticism regarding the theory's physical reach. This offers, at least in a paradigmatic instance, a powerful indication of a structurally well-founded, self-consistent quantum theory.
The Einstein, Podolski and Rosen (EPR) argument aiming to prove the incompleteness of quantum mechanics (QM) was opposed by most EPR's contemporary physicists and is not accepted within the standard interpretation of QM, which maintains that QM is a complete theory. An analysis of the semantic implications of the opponent positions shows that they imply different notions of truth. The introduction of a nonclassical notion of truth within the standard interpretation is usually justified by referring to known theorems that should prove that QM is a contextual and nonlocal theory. However, these theorems are based on a doubtful implicit epistemological assumption. If one renounces it, one can provide an alternative interpretation of QM that it realistic in a semantic sense. Within this interpretation the EPR viewpoint is recovered and QM is considered a (semantically) incomplete, noncontextual and local theory. Furthermore, the new interpretation provides several suggestions for constructing a more general theory embedding QM and for connecting QM with classical physics and relativity.