Quantum mechanics is justifiably held to be the most successful physical theory ever created; yet no universally accepted interpretation of its mathematical formalism exists after a century of debate. We examine the specific claim that classical physics stands as the low-action limit of quantum mechanics, arguing that the deep interpretive difficulties exposed by the quantum formalism, the measurement problem, the subject-object divide, and the nature of scientific representation, were already latent in classical physics, constituting what we call a blind spot of objectivity. Taking quantum theory as an invitation to re-examine the implicit metaphysical commitments bundled with 'classical physics', we explore two key issues-the objective/subjective split and the nature of theoretical representation-and argue that quantum mechanics does not represent a break with classical physics per se but rather brings previously unacknowledged philosophical assumptions into the limelight. We discuss the London-Bauer interpretation and QBism as exemplars of interpretations that embrace this broader reconceptualisation.Quantum mechanics is justifiably held to be the most successful physical theory ever created; yet no universally accepted interpretation of its mathematical formalism exists after a century of debate. We examine the specific claim that classical physics stands as the low-action limit of quantum mechanics, arguing that the deep interpretive difficulties exposed by the quantum formalism, the measurement problem, the subject-object divide, and the nature of scientific representation, were already latent in classical physics, constituting what we call a blind spot of objectivity. Taking quantum theory as an invitation to re-examine the implicit metaphysical commitments bundled with 'classical physics', we explore two key issues-the objective/subjective split and the nature of theoretical representation-and argue that quantum mechanics does not represent a break with classical physics per se but rather brings previously unacknowledged philosophical assumptions into the limelight. We discuss the London-Bauer interpretation and QBism as exemplars of interpretations that embrace this broader reconceptualisation.

physics.hist-phCross-listedarXiv:2609.36207Sep 30, 20260 citations

"Quantum machine" to solve quantum "measurement problem"?

Johan Hansson

Recently a study of the first superposed mechanical quantum object ("machine") visible to the naked eye was published. However, as we show, it turns out that if the object would actually be observed, i.e. would interact with an optical photon, the quantum behavior should vanish. This, the actual observation, has long been suspected in many interpretations of quantum mechanics to be what makes the transition quantum $\rightarrow$ classical, but so far it has not been available for direct experimental study in a mechanical system. We show how any interaction, even a purely quantum one, of sufficient strength can constitute a physical "measurement" - essentially the emergence of an effectively classical object - active observation thus being a sufficient but not necessary criterion. So it seems we have in this case of the "quantum machine" a unique possibility to study, and possibly solve, the long-standing "measurement problem" of quantum mechanics.Recently a study of the first superposed mechanical quantum object ("machine") visible to the naked eye was published. However, as we show, it turns out that if the object would actually be observed, i.e. would interact with an optical photon, the quantum behavior should vanish. This, the actual observation, has long been suspected in many interpretations of quantum mechanics to be what makes the transition quantum $\rightarrow$ classical, but so far it has not been available for direct experimental study in a mechanical system. We show how any interaction, even a purely quantum one, of sufficient strength can constitute a physical "measurement" - essentially the emergence of an effectively classical object - active observation thus being a sufficient but not necessary criterion. So it seems we have in this case of the "quantum machine" a unique possibility to study, and possibly solve, the long-standing "measurement problem" of quantum mechanics.

arXiv:1401.5894Advanced Studies in Theoretical PhysicsJan 1, 20150 citations

The Principles of Classical and Quantum Mechanics

Maurice A. de Gosson

Jan 1, 20020 citations

The classical boundaries of the EPR argument and quantum ontology

Vincenzo Chilla

Von Neumann's Hilbert-space formalism of quantum mechanics constitutes a logico-physical theory of observed or measured reality. Imposing the logical constraint of Booleanity, essential for objectively shareable descriptions among observers, reveals the physical meaning of classicality inherently embedded within the formalism itself. Starting from this consideration, the present work reformulates the quantum-classical transition via Hilbert-space classical mechanics (HCM), grounding classicality not in the dynamical limit ( $\hbar \to 0$ ), but in the logical constraint of Booleanity (i.e., the mutual commutativity of preparable states). Within this state-centric framework, applying the Einstein-Podolsky-Rosen (EPR) criterion alongside locality and measurement independence reduces standard quantum mechanics to the HCM model. Thus, the EPR argument reveals not quantum incompleteness, but the implicit classical boundaries of its own premises. To resolve this impasse, we articulate a nuanced quantum ontology grounded in a fundamental structural bipartition between the observational environment and the observed object, which accommodates three categorical distinctions: ontic, processional, and tropos-existential. Building on this, we propose a criterion of objective reality wherein descriptive objectivity is treated as merely a sufficient condition for physical reality. This addresses the historical Bohr-Einstein ambiguity, enabling the quantum formalism to ontologically unify objective measured phenomena and non-objective observed interference within a context-dependent framework.Von Neumann's Hilbert-space formalism of quantum mechanics constitutes a logico-physical theory of observed or measured reality. Imposing the logical constraint of Booleanity, essential for objectively shareable descriptions among observers, reveals the physical meaning of classicality inherently embedded within the formalism itself. Starting from this consideration, the present work reformulates the quantum-classical transition via Hilbert-space classical mechanics (HCM), grounding classicality not in the dynamical limit ($\hbar \to 0$), but in the logical constraint of Booleanity (i.e., the mutual commutativity of preparable states). Within this state-centric framework, applying the Einstein-Podolsky-Rosen (EPR) criterion alongside locality and measurement independence reduces standard quantum mechanics to the HCM model. Thus, the EPR argument reveals not quantum incompleteness, but the implicit classical boundaries of its own premises. To resolve this impasse, we articulate a nuanced quantum ontology grounded in a fundamental structural bipartition between the observational environment and the observed object, which accommodates three categorical distinctions: ontic, processional, and tropos-existential. Building on this, we propose a criterion of objective reality wherein descriptive objectivity is treated as merely a sufficient condition for physical reality. This addresses the historical Bohr-Einstein ambiguity, enabling the quantum formalism to ontologically unify objective measured phenomena and non-objective observed interference within a context-dependent framework.

quant-pharXiv:2606.07826Jun 9, 20260 citations

REALITY IN HEISENBERG'S PHILOSOPHY - Chapter Eight of Heelan's Quantum Mechanics and Objectivity

Patrick A. Heelan

This chapter contains a study of Heisenberg's views of the ontological content of quantum mechanics from I925 until the present day. During the quantum revolution of I925, he began by accepting a Berkeley-type empiricism in which the reality of a quantum mechanical system was reduced to that of a set of observation events, which were, however, acausally connected and in consequence did not constitute a stable phenomenal object of experimental knowledge. After 1955, he professed a modified form of Kantian philosophy whose starting point was the existence of universal and necessary scientific laws. Those universal and necessary scientific laws from which Kant started have been shown to belong only to restricted domains of intuitive experience (the domain of everyday life and classical physics). Heisenberg defines noumenal reality as the object of an intellectual intuition (episteme) which, however, is a kind of knowledge we do not possess. We know noumenal reality only through symbols in an intellectually patterned experience. There are two kinds of noumenal reality: there is the thing-in-itself which is the correlate of the phenomenal object, and there is the dunamis (or Aristotelian potentia or objective tendency) which is the correlate of the quantum mechanical system (e.g., elementary particle, atom, etc.). The latter is the noumenal correlate of the phenomenal or experienced union of subject and object taking place in the act of observation. The importance of universal symmetries in the expression of general laws of nature is stressed by Heisenberg, and these constitute for him the true basis for transcendental philosophy.This chapter contains a study of Heisenberg's views of the ontological content of quantum mechanics from I925 until the present day. During the quantum revolution of I925, he began by accepting a Berkeley-type empiricism in which the reality of a quantum mechanical system was reduced to that of a set of observation events, which were, however, acausally connected and in consequence did not constitute a stable phenomenal object of experimental knowledge. After 1955, he professed a modified form of Kantian philosophy whose starting point was the existence of universal and necessary scientific laws. Those universal and necessary scientific laws from which Kant started have been shown to belong only to restricted domains of intuitive experience (the domain of everyday life and classical physics). Heisenberg defines noumenal reality as the object of an intellectual intuition (episteme) which, however, is a kind of knowledge we do not possess. We know noumenal reality only through symbols in an intellectually patterned experience. There are two kinds of noumenal reality: there is the thing-in-itself which is the correlate of the phenomenal object, and there is the dunamis (or Aristotelian potentia or objective tendency) which is the correlate of the quantum mechanical system (e.g., elementary particle, atom, etc.). The latter is the noumenal correlate of the phenomenal or experienced union of subject and object taking place in the act of observation. The importance of universal symmetries in the expression of general laws of nature is stressed by Heisenberg, and these constitute for him the true basis for transcendental philosophy.

Jan 1, 19650 citations

\rightarrow

classical, but so far it has not been available for direct experimental study in a mechanical system. We show how any interaction, even a purely quantum one, of sufficient strength can constitute a physical "measurement" - essentially the emergence of an effectively classical object - active observation thus being a sufficient but not necessary criterion. So it seems we have in this case of the "quantum machine" a unique possibility to study, and possibly solve, the long-standing "measurement problem" of quantum mechanics.

\hbar \to 0

), but in the logical constraint of Booleanity (i.e., the mutual commutativity of preparable states). Within this state-centric framework, applying the Einstein-Podolsky-Rosen (EPR) criterion alongside locality and measurement independence reduces standard quantum mechanics to the HCM model. Thus, the EPR argument reveals not quantum incompleteness, but the implicit classical boundaries of its own premises. To resolve this impasse, we articulate a nuanced quantum ontology grounded in a fundamental structural bipartition between the observational environment and the observed object, which accommodates three categorical distinctions: ontic, processional, and tropos-existential. Building on this, we propose a criterion of objective reality wherein descriptive objectivity is treated as merely a sufficient condition for physical reality. This addresses the historical Bohr-Einstein ambiguity, enabling the quantum formalism to ontologically unify objective measured phenomena and non-objective observed interference within a context-dependent framework.