In this paper we attempt to investigate the historical and methodological aspects of the developments related to superfluid helium, concentrating on the period between 1941 and 1955. During this period, the various developments constituted a series of steps towards redefining and refining the two-fluid concept devised to explain the unexpected macroscopic behaviour of superfluid helium. The idea that superfluids are essentially ‘quantum structures on a macroscopic scale’ functioned as a heuristic principle which guided the theoretical physicists engaged (...) in the above research programme. (shrink)

The purpose of this paper is to present an overview of emergent examples of macroscopic quantum phenomena. While quantum theory asserts that such quantum behaviors as superposition, entanglement, and coherence are possible for all objects, assumptions that quantum processes operate exclusively within the quantum realm have contributed to on-going bias toward presumed primacy of classical physics in the macroscopic realm. Non-trivial quantum macroscopic effects are now recognized in the fields of (...) biology, quantum physics, quantum computing, quantum astronomy, and neuroscience, with implications for medicine, psychology and sociology. Robust examples of macroscopic quantum coherence and entanglement contain unmistakable biological advantages, such as are observed in the green sulphur bacteria photosynthesis transfer mechanism, and in the navigational system of the European Robin. Macroscopic quantum processes in the form of an olfactory electron tunneling mechanism best account for the otherwise inexplicable difference observed in the odor of identically-shaped molecules. Evidence of reverse-direction causality is apparent in experiments with large numbers of photons and human subjects. Entanglement, retrocausality, and superposition of states are suggested as causal factors to account for increases in efficacy of the placebo effect. Alternate histories of "flashbulb memories" and embodied cognition are considered as possible examples of superposition of states in a holographic multiverse in which the many worlds of the multiverse and the many worlds of quantum mechanics might just be one and the same thing. Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;}. (shrink)

Supraleitfähigkeit und Superfluidität sind die einzigen bekannten makroskopischen Quantenphänomene. Ihre Untersuchung liefert interessante Hinweise, um einige der Fragen zu verstehen, die mit den Grenzen der Gültigkeit der Quantenmechanik verbunden sind. In diesem Aufsatz wollen wir den Prozeß entzifferen, durch den ein beobachtetes unerwartetes Phänomen in ein physikalisches Problem übergeführt wird, und wir zeigen die kontinuierliche Reinterpretation der Begriffe, um eine zufriedenstellende Erklärung der Supraleitfähigkeit und Superfluidität zu erreichen.

There is an underlying assumption in the social sciences that consciousness and social life are ultimately classical physical/material phenomena. In this ground-breaking book, Alexander Wendt challenges this assumption by proposing that consciousness is, in fact, a macroscopic quantum mechanical phenomenon. In the first half of the book, Wendt justifies the insertion of quantum theory into social scientific debates, introduces social scientists to quantum theory and the philosophical controversy about its interpretation, and then defends the (...) class='Hi'>quantum consciousness hypothesis against the orthodox, classical approach to the mind-body problem. In the second half, he develops the implications of this metaphysical perspective for the nature of language and the agent-structure problem in social ontology. Wendt's argument is a revolutionary development which raises fundamental questions about the nature of social life and the work of those who study it. (shrink)

This NATO Advanced Study Institute centered on large-scale molecular systems: Quantum mechanics, although providing a general framework for the description of matter, is not easily applicable to many concrete systems of interest; classical statistical methods, on the other hand, allow only a partial picture of the behaviour of large systems. The aim of the ASI was to present both aspects of the subject matter and to foster interaction between the scientists working in these important areas of theoretical physics and (...) theoretical chemistry. The quantum-mechanical part was mostly based on the operator-algebraic formulation of quantum mechanics and comprised quantum statistics of infinite systems with special em phasis on macroscopic observables, equilibrium conditions, irreversibility on the one hand, symmetry breaking for molecules in the radiation field and macroscopic quantum phenomena in the theory of superconductivity (BCS-theory) on the other hand. In addition, phase-space methods for many-body systems were also presented. Statistical physics was the main topic in the other lectures of the School; much emphasis was put on the statistical features of macros copic ("large") systems, the lectures dealt with mass and energy transport im polymers, in gels and in microemulsions, with aggregation and growth phenomena, with relaxation in complex, correlated systems, with conduction and optical properties of polymers, and with the means of describing disordered systems, above all fractals and related hierarchical models. (shrink)

The apparent ineffectuality of quantum physics to reconcile its evolution rule with measurement phenomena has polarized the community of scholars working on the subject into, roughly, two sorts of camps. On the one side there are those who perceive the problem to be that of finding an interpretation of the conceptual structures of quantum theory whereon the two elements can be reconciled without having to revise the canonical understanding of either. On the other side are those who (...) see measurement phenomena as posing a challenge: the challenge of revising either the canonical equation or its canonical application in such a way that no conflict arises between it and laboratory data. ;This dissertation focuses on proposals of the latter sort. The centerpiece of the thesis is a reinterpretation of the Theory of Macrosystems of Daneri, Loinger and Prosperi. I show that this theory is most charitably interpreted as a proposal for reconciling measurement phenomena, not so much with Schrodinger dynamics, but rather with a constraint on the evolution map. It is, in other words, an account of how measurement phenomena is consistent with a certain set of dynamical behaviors. The focus on behaviors rather than equations and their solutions is characteristic of recent approaches to studying phenomena in classical contexts, both of phenomena to do with the approach to equilibrium and in situations involving far-from-equilibrium phenomena. The focus on behaviors is motivated by recognition that equations of motion for microscopic subcomponents of many-body systems do not wear on their countenances anything useful about the macroscopic behaviors of the systems they collectively describe--and are, in addition, virtually unsolvable. Therefore it profits an investigator to do without microscopic equations of motion in analyzing phenomena. The Theory of Macrosystems likewise "does without" equations of motion; I show that the account it gives is independent of closed-form rules of evolution. For this reason I call it an agnostic solution to the measurement problem--and show that this is an altogether different approach to the problem than any other so far conceived. (shrink)

The apparent ineffectuality of quantum physics to reconcile its evolution rule with measurement phenomena has polarized the community of scholars working on the subject into, roughly, two sorts of camps. On the one side there are those who perceive the problem to be that of finding an interpretation of the conceptual structures of quantum theory whereon the two elements can be reconciled without having to revise the canonical understanding of either. On the other side are those who (...) see measurement phenomena as posing a challenge: the challenge of revising either the canonical equation or its canonical application in such a way that no conflict arises between it and laboratory data. ;This dissertation focuses on proposals of the latter sort. The centerpiece of the thesis is a reinterpretation of the Theory of Macrosystems of Daneri, Loinger and Prosperi. I show that this theory is most charitably interpreted as a proposal for reconciling measurement phenomena, not so much with Schrodinger dynamics, but rather with a constraint on the evolution map. It is, in other words, an account of how measurement phenomena is consistent with a certain set of dynamical behaviors. The focus on behaviors rather than equations and their solutions is characteristic of recent approaches to studying phenomena in classical contexts, both of phenomena to do with the approach to equilibrium and in situations involving far-from-equilibrium phenomena. The focus on behaviors is motivated by recognition that equations of motion for microscopic subcomponents of many-body systems do not wear on their countenances anything useful about the macroscopic behaviors of the systems they collectively describe--and are, in addition, virtually unsolvable. Therefore it profits an investigator to do without microscopic equations of motion in analyzing phenomena. The Theory of Macrosystems likewise "does without" equations of motion; I show that the account it gives is independent of closed-form rules of evolution. For this reason I call it an agnostic solution to the measurement problem--and show that this is an altogether different approach to the problem than any other so far conceived. (shrink)

With reference to recently proposed theoretical models accounting for reduction in terms of a unified dynamics governing all physical processes, we analyze the problem of working out a worldview accommodating our knowledge about natural phenomena. We stress the relevant conceptual differences between the considered models and standard quantum mechanics. In spite of the fact that both theories describe systems within a genuine Hilbert space framework, the peculiar features of the spontaneous reduction models limit drastically the states which are (...) dynamically stable. This fact by itself allows one to work out an interpretation of the formalism which makes it possible to give a satisfactory description of the world in terms of the values taken by an appropriately defined mass density function in ordinary configuration space. A topology based on this function and which is radically different from the one characterizing the Hilbert space is introduced, and in terms of it the idea of similarity of macroscopic situations is precisely defined. Finally, the formalism and the interpretation are shown to yield a natural criterion for establishing the psychophysical parallelism. The conclusion is that, within the considered theories and at the nonrelativistic level, one can satisfy all sensible requirements for a completely satisfactory macro-objective description of reality. (shrink)

It is shown that an approach to quantum phenomena in which charged particles are treated as macroscopically extended periodic disturbances in a nonlinear c-number field, interacting with each other via massless excitations of that field, leads almost uniquely to the five basic equations of classical electrodynamics: the Lorentz force law and Maxwell's equations. The fundamental electromagnetic quantity in this approach is the 4-vector potential Aα—interpreted absolutely as a measure of the local shift of each particle off its mass (...) shell—rather than theE andB fields, and it thus provides a new viewpoint on the questions of Aharonov-Bohm phase shifts, the existence of magnetic monopoles, and the role of gauge invariance. (shrink)

In this chapter, I argue that Aristotle’s doctrine of hylomorphism, which conceived the natural world as consisting of substances which are metaphysically composed of matter and form, is ripe for rehabilitation in the light of quantum physics. I begin by discussing Aristotle’s conception of matter and form, as it was understood by Aquinas, and how Aristotle’s doctrine of hylomorphism was ‘physicalised’ and eventually abandoned with the rise of microphysicalism. I argue that the phenomenon of quantum entanglement, and the (...) emergence of irreducibly macroscopic phenomena in finite temperature quantum systems, have given us good reasons to doubt the truth of microphysicalism. In support of my argument, I show how to construct a hylomorphic interpretation of the de Broglie-Bohm theory that posits a single Cosmic Substance. I then show how to construct a hylomorphic interpretation of an alternative ‘contextual’ wave function collapse theory (recently proposed by the physicists Barbara Drossel and George Ellis) which posits a plurality of thermal substances. Both of these neo-Aristotelian ontologies reject the microphysicalist dogma that nature consists solely of some set of microscopic constituents. (shrink)

A two boundary quantum mechanics without time ordered causal structure is advocated as consistent theory. The apparent causal structure of usual “near future” macroscopic phenomena is attributed to a cosmological asymmetry and to rules governing the transition between microscopic to macroscopic observations. Our interest is a heuristic understanding of the resulting macroscopic physics.

Advocates of the New Mechanicism in philosophy of science argue that scientific explanation often consists in describing mechanisms responsible for natural phenomena. Despite its successes, one might think that this approach does not square with the ontological strictures of quantum mechanics. New Mechanists suppose that mechanisms are composed of objects with definite properties, which are interconnected via local causal interactions. Quantum mechanics calls these suppositions into question. Since mechanisms are hierarchical it appears that even macroscopic mechanisms (...) must supervene on a set of “objects” that behave non-classically. In this paper we argue, in part by appeal to the theory of quantum decoherence, that the universal validity of quantum mechanics does not undermine neo-mechanistic ontological and explanatory claims as they occur within in classical domains. Additionally, we argue that by relaxation of certain classical assumptions, mechanistic explanatory strategies can sometimes be carried over into the quantum domain. (shrink)

A theoretical framework called "Quantum Brain Dynamics" to describe long range ordered dynamics of the quantum system of electromagnetic field and water dipole field in the brain is proposed as a revival of the original idea developed by Umezawa in the early 1960s. Based on Umezawa’s world view of quantum field theory, the manifestation of long range ordered dynamics is a macroscopic object of quantum origin, and so it reveals the existence of specific macroscopic (...) objects in the brain called "tunneling photon water." Tunneling photon water is shown to manifest several interesting quantum phenomena involving coherent photon emission and transmission, and is suggested to play an important role in quantum brain dynamics. The ordered quantum dynamics of such a macroscopic condensate of tunneling photons with nonvanishing effective charge and mass as tunneling photon water is governed by the macroscopic Schrödinger equation, and ensures superconducting phenomena in the brain at body temperature. The meaning of quantum brain dynamics is clearly explained for brain and cognitive scientists who have been confused by either the overstatement with misplaced quantum concepts usually given by those not appropriately schooled in physics or the understatement with textbook quantum concepts given by technical physicists. (shrink)

Consideration is given to recent attempts to solve the objectification problem of quantum mechanics by considering nonlinear and stochastic modifications of Schrödinger's evolution equation. Such theories agree with all predictions of standard quantum mechanics concerning microsystems but forbid the occurrence of superpositions of macroscopically different states. It is shown that the appropriate interpretation for such theories is obtained by replacing the probability densities of standard quantum mechanics with mass densities in real space. Criteria allowing a precise characterization (...) of the idea of similarity and difference of macroscopic situations are presented and it is shown how they lead to a theoretical picture which is fully compatible with a macrorealistic position about natural phenomena. (shrink)

In the context of theories of the connection between mind and brain, physicalism is the demand that all is basically purely physical. But the conception of “physical” embodied in this demand is characterized essentially by the properties of the physical that hold in classical physical theories. Certain of those properties contradict the character of the physical in quantum mechanics, which provides a better, more comprehensive, and more fundamental account of phenomena. It is argued that the difficulties that have (...) plagued physicalists for half a century, and that continue to do so, dissolve when the classical idea of the physical is replaced by its quantum successor. The argument is concretized in way that makes it accessible to non-physicists by exploiting the recent evidence connecting our conscious experiences to macroscopic measurable synchronous oscillations occurring in wellseparated parts of the brain. A specific new model of the mind-brain connection that is fundamentally quantum mechanical but that ties conscious experiences to these macroscopic synchronous oscillations is used to illustrate the essential disparities between the classical and quantum notions of the physical, and in particular to demonstrate the failure in the quantum world of the principle of the causal closure of the physical, a failure that goes beyond what is entailed by the randomness in the outcomes of observations, and that accommodates the efficacy in the brain of conscious intention. (shrink)

I show in this paper why the universality of quantum mechanics at all scales, which implies the possibility of Schrodinger's Cat and Wigner's Friend thought experiments, cannot be experimentally confirmed, and why macroscopic superpositions in general cannot be observed or measured, even in principle. Through the relativity of quantum superposition and the transitivity of correlation, it is shown that from the perspective of an object that is in quantum superposition relative to a macroscopic measuring device (...) and observer, the observer is already sufficiently well correlated to the measuring device that once the object correlates to the measuring device, there is no time period in which the observer can perform an appropriate interference experiment to show that the measuring device is in a superposition. (shrink)

The paper reviews the current situation regarding a new theory of brain dynamics put forward by the authors in an earlier publication. Motivation for the theory is discussed in terms of two issues: the long-standing problem of accounting for the stability and nonlocal properties of memory, and the experimental and theoretical evidence against the classical theory of brain action. It is shown that the new theory provides an explanation and a conceptually unifying framework for phenomena of brain action that (...) resist classical explanation. Further independent experiments provide strong additional support for the theory. The fact that this theory incorporates quantum mechanisms in an essential way is considered to be of wide scientific interest in view of the unique status of the brain in relation to the physical, biological, and mental orders in nature. (shrink)

There are many blank areas in understanding the brain dynamics and especially how it gives rise to consciousness. Quantum mechanics is believed to be capable of explaining the enigma of conscious experience, however till now there is not good enough model considering both the data from clinical neurology and having some explanatory power! In this paper is presented a novel model in defence of macroscopic quantum events within and between neural cells. The beta-neurexin-neuroligin-1 link is claimed to (...) be not just the core of the central neural synapse, instead it is a device mediating entanglement between the cytoskeletons of the cortical neurons. Thus a macroscopic quantum state can extend throughout large brain cortical areas and the subsequent collapse of the wavefunction could affect simultaneously the subneuronal events in millions of neurons. The beta-neurexin-neuroligin-1 complex also controls the process of exocytosis and provides an interesting and simple mechanism for retrograde signalling during learning-dependent changes in synaptic connectivity. (shrink)

This paper is concerned with the description of the process of measurement within the context of a quantum theory of the physical world. It is noted that quantum mechanics permits a quasi-classical description of those macroscopic phenomena in terms of which the observer forms his perceptions. Thus, the process of measurement in quantum mechanics can be understood on the quasi-classical level by transcribing from the strictly classical observables of Newtonian physics to their quasi-classical counterparts the (...) known rules for the measurement of the former. The remaining physical problem is the delineation of the circumstances in which the correlation of a peculiarly quantum mechanical observable A with a classically measurable observable B can result in a significant measurement of A. This is undertaken within the context of quantum theory. The resulting clarification of the process of measurement has important implications relative to the philosophic interpretation of quantum mechanics. (shrink)

This paper uses a non-distributive system of Boolean fractions (a|b), where a and b are 2-valued propositions or events, to express uncertain conditional propositions and conditional events. These Boolean fractions, 'a if b' or 'a given b', ordered pairs of events, which did not exist for the founders of quantum logic, can better represent uncertain conditional information just as integer fractions can better represent partial distances on a number line. Since the indeterminacy of some pairs of quantum events (...) is due to the mutual inconsistency of their experimental conditions, this algebra of conditionals can express indeterminacy. In fact, this system is able to express the crucial quantum concepts of orthogonality, simultaneous verifiability, compatibility, and the superposition of quantum events, all without resorting to Hilbert space. A conditional (a|b) is said to be "inapplicable" (or "undefined") in those instances or models for which b is false. Otherwise the conditional takes the truth-value of proposition a. Thus the system is technically 3-valued, but the 3rd value has nothing to do with a state of ignorance, nor to some half-truth. People already routinely put statements into three categories: true, false, or inapplicable. As such, this system applies to macroscopic as well as microscopic events. Two conditional propositions turn out to be simultaneously verifiable just in case the truth of one implies the applicability of the other. Furthermore, two conditional propositions (a|b) and (c|d) reside in a common Boolean sub-algebra of the non-distributive system of conditional propositions just in case b = d, their conditions are equivalent. Since all aspects of quantum mechanics can be represented with this near classical logic, there is no need to adopt Hilbert space logic as ordinary logic, just a need perhaps to adopt propositional fractions to do logic, just as we long ago adopted integer fractions to do arithmetic. The algebra of Boolean fractions is a natural, near-Boolean extension of Boolean algebra adequate to express quantum logic. While this paper explains one group of quantum anomalies, it nevertheless leaves no less mysterious the 'influence-at-a-distance', quantum entanglement phenomena. A quantum realist must still embrace non-local influences to hold that "hidden variables" are the measured properties of particles. But that seems easier than imaging wave-particle duality and instant collapse, as offered by proponents of the standard interpretation of quantum mechanics. (shrink)

In semiclassical mechanics one finds explanations of quantum phenomena that appeal to classical structures. These explanations are prima facie problematic insofar as the classical structures they appeal to do not exist. Here I defend the view that fictional structures can be genuinely explanatory by introducing a model-based account of scientific explanation. Applying this framework to the semiclassical phenomenon of wavefunction scarring, I argue that not only can the fictional classical trajectories explain certain aspects of this quantum phenomenon, (...) but also that an explanation that does not make reference to these classical structures is, in a certain sense, deficient. (shrink)

This paper is concerned with the description of the process of measurement within the context of a quantum theory of the physical world. It is noted that quantum mechanics permits a quasi-classical description of those macroscopic phenomena in terms of which the observer forms his perceptions. Thus, the process of measurement in quantum mechanics can be understood on the quasi-classical level by transcribing from the strictly classical observables of Newtonian physics to their quasi-classical counterparts the (...) known rules for the measurement of the former. The remaining physical problem is the delineation of the circumstances in which the correlation of a peculiarly quantum mechanical observable A with a classically measurable observable B can result in a significant measurement of A. This is undertaken within the context of quantum theory. The resulting clarification of the process of measurement has important implications relative to the philosophic interpretation of quantum mechanics. (shrink)

The renewed interest in the foundations of quantum statistical mechanics in recent years has led us to study John von Neumann’s 1929 article on the quantum ergodic theorem. We have found this almost forgotten article, which until now has been available only in German, to be a treasure chest, and to be much misunderstood. In it, von Neumann studied the long-time behavior of macroscopic quantum systems. While one of the two theorems announced in his title, the (...) one he calls the “quantum H-theorem,” is actually a much weaker statement than Boltzmann’s classical H-theorem, the other theorem, which he calls the “quantum ergodic theorem,” is a beautiful and very non-trivial result. It expresses a fact we call “normal typicality” and can be summarized as follows: For a “typical” finite family of commuting macroscopic observables, every initial wave function ψ0 from a micro-canonical energy shell so evolves that for most times t in the long run, the joint probability distribution of these observables obtained from ψt is close to their micro-canonical distribution. (shrink)

Quantum entanglement lies at the foundation of quantum mechanics. Witness Schrödinger highlighting entanglement with his puzzling cat thought experiment and Einstein deriding it as “spooky action at a distance.” Nonetheless, quantum entanglement has been verified experimentally and is essential for quantum information and quantum computing. The quantum superposition principle, together with entanglement, dramatically contrasts the quantum from the classical description of reality. We attempt to integrate physical reality with a Christian worldview.

This paper is concerned with the description of the process of measurement within the context of a quantum theory of the physical world. It is noted that quantum mechanics permits a quasi-classical description (classical in the limited sense implied by the correspondence principle of Bohr) of those macroscopic phenomena in terms of which the observer forms his perceptions. Thus, the process of measurement in quantum mechanics can be understood on the quasi-classical level by transcribing from (...) the strictly classical observables of Newtonian physics to their quasi-classical counterparts the known rules for the measurement of the former. The remaining physical problem is the delineation of the circumstances in which the correlation of a peculiarly quantum mechanical observable A with a classically measurable observable B can result in a significant measurement of A. This is undertaken within the context of quantum theory. The resulting clarification of the process of measurement has important implications relative to the philosophic interpretation of quantum mechanics. (shrink)

This work is part of a program which has the aim to investigate which phenomena can be explained by nonlinear effects in classical mechanics and which ones require the new axioms of quantum mechanics. In this paper, we construct a nonlinear field equation which admits soliton solutions. These solitons exibit a dynamics which is similar to that of quantum particles.

In my 2013 article, “A New Theory of Free Will”, I argued that several serious hypotheses in philosophy and modern physics jointly entail that our reality is structurally identical to a peer-to-peer (P2P) networked computer simulation. The present paper outlines how quantum phenomena emerge naturally from the computational structure of a P2P simulation. §1 explains the P2P Hypothesis. §2 then sketches how the structure of any P2P simulation realizes quantum superposition and wave-function collapse (§2.1.), quantum indeterminacy (...) (§2.2.), wave-particle duality (§2.3.), and quantum entanglement (§2.4.). Finally, §3 argues that although this is by no means a philosophical proof that our reality is a P2P simulation, it provides ample reasons to investigate the hypothesis further using the methods of computer science, physics, philosophy, and mathematics. (shrink)

It so happens that classical physical theories can be interpreted as a representation of local interactions between systems with determinate properties. Orthodox quantum mechanics, which is one of our most experimentally well-confirmed theories, is notoriously resistant to being interpreted in terms of the above framework. Bell-type theorems and Bell-type experiments have made such an interpretation impossible. In the early sixties, John Bell demonstrated that any theory that represents its domain in terms of the above framework satisfies a set of (...) inequalities, the so-called Bell inequalities. Experiments on quantum phenomena violate Bell-type inequalities. By a simple modus tollens, the upshot is that no theory that includes all the elements of the above framework can recover all statistical predictions of quantum mechanics. Philosophers have been trying to interpret this result, that is, to understand what the world might be like if it is true that physical interactions between systems are non-local, or that physical systems do not possess determinate properties. This line of thought found its climax in program of Òexperimental metaphysicsÓ that developed after the violation of Bell-type inequalities was observed. Experimental metaphysics consists in deriving metaphysical conclusions from the Bell-type experimental results. The mainstream interpretation within experimental metaphysics is that Bell-type experiments force us to accept the existence of a form of non-locality at the ontological level, but a form that we can consider benign because it is of a non-causal type. In my dissertation, I assess to what extent philosophical investigation can help us decide what the world is like on the basis of our best physical theories, from the point of view of the quantum domain and with an emphasis on Bell-type phenomena. My conclusions point to a more modest view on the possible achievements of philosophy of physics than the experimental metaphysics program would have us believe. In the first part of my dissertation, I investigate what role philosophy of physics can legitimately hope to play in the development and evaluation of various accounts of quantum phenomena. I claim that it is not the role of philosophy of physics to impose criteria of acceptability on physical theories, in addition to coherence and empirical adequacy. By contrast, I take in my dissertation that the legitimate role of philosophy of physics is to clearly determine what is imposed by the phenomena and our best theories from what is a matter of preference on the basis of the structural analysis of the phenomena and theories. In the second part of my dissertation, I turn to the more specific case of the interpretation of Bell-type theorems and Bell-type phenomena. I undertake a systematic examination of the mainstream interpretation. I show that the mainstream interpretation includes three claims, one about locality, another one about causation and a last one about holism. I utilize theories of locality and causation in order to assess these three claims. On the one hand, the upshot of my analysis is that the claim about locality can be supported by a rigorous theory of locality. On the other hand, no theory of probabilistic causation can support the claims of the mainstream interpretation about causation when it is construed as a strong program of experimental metaphysics yielding conclusions about the ontology of the world. That said, weakened versions of the mainstream interpretation, those that do without conclusions about the ontology of the world, can be made compatible with some theories of probabilistic causation. In particular, the mainstream interpretation can be rigorously supported if its claims are restricted to the empirical level. (shrink)

In this paper, we discuss the macroscopic quantum behavior of simple superconducting circuits. Starting from a Lagrangian for electromagnetic field with broken gauge symmetry, we construct a quantum circuit model for a superconducting weak link (SQUID) ring, together with the appropriate canonical commutation relations. We demonstrate that this model can be used to describe macroscopic excitations of the superconducting condensate and the localized charge states found in some ultrasmall-capacitance weak-link devices.

The renewed interest in the foundations of quantum statistical mechanics in recent years has led us to study John von Neumann’s 1929 article on the quantum ergodic theorem. We have found this almost forgotten article, which until now has been available only in German, to be a treasure chest, and to be much misunderstood. In it, von Neumann studied the long-time behavior of macroscopic quantum systems. While one of the two theorems announced in his title, the (...) one he calls the “quantum H-theorem,” is actually a much weaker statement than Boltzmann’s classical H-theorem, the other theorem, which he calls the “quantum ergodic theorem,” is a beautiful and very non-trivial result. It expresses a fact we call “normal typicality” and can be summarized as follows: For a “typical” finite family of commuting macroscopic observables, every initial wave function ψ0 from a micro-canonical energy shell so evolves that for most times t in the long run, the joint probability distribution of these observables obtained from ψ is close to.. (shrink)

In this paper we analyze the resilience to decoherence of the Macroscopic Quantum Superpositions (MQS) generated by optimal phase-covariant quantum cloning according to two coherence criteria, both based on the concept of Bures distance in Hilbert spaces. We show that all MQS generated by this system are characterized by a high resilience to decoherence processes. This analysis is supported by the results of recent MQS experiments of N=3.5×104 particles.

The Schrodinger's Cat and Wigner's Friend thought experiments, which logically follow from the universality of quantum mechanics at all scales, have been repeatedly characterized as possible in principle, if perhaps difficult or impossible for all practical purposes. I show in this paper why these experiments, and interesting macroscopic superpositions in general, are actually impossible in principle. First, no macroscopic superposition can be created via the slow process of natural quantum packet dispersion because all macroscopic objects (...) are inundated with decohering interactions that constantly localize them. Second, the SC/WF thought experiments depend on von Neumann-style amplification to achieve quickly what quantum dispersion achieves slowly. Finally, I show why such amplification cannot produce a macroscopic quantum superposition of an object relative to an external observer, no matter how well isolated the object from the observer, because: the object and observer are already well correlated to each other; and reducing their correlations to allow the object to achieve a macroscopic superposition relative to the observer is equally impossible, in principle, as creating a macroscopic superposition via the process of natural quantum dispersion. (shrink)

We consider an isolated, macroscopic quantum system. Let H be a microcanonical “energy shell,” i.e., a subspace of the system’s Hilbert space spanned by the (finitely) many energy eigenstates with energies between E and E + δE. The thermal equilibrium macro-state at energy E corresponds to a subspace Heq of H such that dim Heq/ dim H is close to 1. We say that a system with state vector ψ H is in thermal equilibrium if ψ is “close” (...) to Heq. We show that for “typical” Hamiltonians with given eigenvalues, all initial state vectors ψ0 evolve in such a way that ψt is in thermal equilibrium for most times t. This result is closely related to von Neumann’s quantum ergodic theorem of 1929. (shrink)

This paper outlines the qualitative foundations of a “quasiclassical” theory in which particles are pictured as spatially extended periodic excitations of a universal background field, interacting with each other via nonlinearity in the equations of motion for that field, and undergoing collapse to a much smaller volume if and when they are detected. The theory is based as far as possible directly on experiment, rather than on the existing quantum mechanical formalism, and it offers simple physical interpretations of such (...) concepts as mass, 4-momentum, interaction, potentials, and quantization; it may lead directly to the standard equations of quantum theory, such as the multiparticle Schrödinger equation, without going through the conventional process of “quantizing” a classical theory. The theory also provides an alternative framework in which to discuss wave-particle duality and the quantum “measurement problem”; in particular, it is suggested that the unpredictability of quantum phenomena may arise from “deterministic chaos” in the behavior of the background field. (shrink)

The question of whether an «understanding» of quantum phenomena is possible, as raised by Cushing , is considered in terms of a possible revision of basic ontological assumptions which would make rational the pursuit of such an understanding. It is argued that the quantum theory imposes new constraints on ontology which force us to revise classical presuppositions about attributing properties to physical systems, about locality and individuality, and about interaction and space‐like separability. Through such ontological revision, it (...) is argued, one may still rationally hope to satisfy the typically realist thirst for an understanding of quantum phenomena. (shrink)

We analyze the back-action of nonlinear atomic homodyning measurements on steady-state “macroscopic superpositions” that can be generated in high-Q microwave cavities. We show that a full characterization of the state requires measurements such that the macroscopic superposition is irreversibly destroyed, that is, it cannot be reconstructed by using the scheme that was used to generate it in the first place.

The recent renewed interest in the foundation of quantum statistical mechanics and in the dynamics of isolated quantum systems has led to a revival of the old approach by von Neumann to investigate the problem of thermalization only in terms of quantum dynamics in an isolated system [1, 2]. It has been demonstrated in some general or concrete settings that a pure initial state evolving under quantum dynamics indeed approaches an equilibrium state [3–9]. The underlying idea (...) that a single pure quantum state can fully describe thermal equilibrium has also become much more concrete [10–12]. (shrink)

In this study, we solve analytically the Schrödinger equation for a macroscopic quantum oscillator as a central system coupled to two environmental micro-oscillating particles. Then, the double-slit interference patterns are investigated in two limiting cases, considering the limits of uncertainty in the position probability distribution. Moreover, we analyze the interference patterns based on a recent proposal called stochastic electrodynamics with spin. Our results show that when the quantum character of the macro-system is decreased, the diffraction pattern becomes (...) more similar to a classical one. We also show that, depending on the size of the slits, the predictions of quantum approach could be apparently different with those of the aforementioned stochastic description. (shrink)

The correlations between distant systems in typical quantum situations, such as Einstein-Podolosky-Rosen experiments, strongly suggest that the quantum realm involves curious types of non-Iocal influences. In this paper, I study in detail the nature of these non-Iocal influences, as depicted by various quantum theories. I show how different quantum theories realise non-Iocality in different ways, whichreflect different ontological settings.

The correlations between distant systems in typical quantum situations, such as Einstein-Podolosky-Rosen experiments, strongly suggest that the quantum realm involves curious types of non-Iocal influences. In this paper, I study in detail the nature of these non-Iocal influences, as depicted by various quantum theories. I show how different quantum theories realise non-Iocality in different ways, whichreflect different ontological settings.

We abandon as redundant the assumption that there exists something more in the physical world than action quanta, which constitute the atoms of the events of which the four-dimensional world consists. We derive metric, energy, matter, etc., from action and the structure formed by the quanta. In the microworld thequantization of space so introduced implies deviations from conventional metrics that make it possible in particular to explain nonlocality. The uncertainty relations, then, in conjunction with the action-based metric, appear to play (...) an essential role in making direct physical contact between emission and absorption events (i.e., retroactivity) possible, which concretely answers Bohr's conjecture that microprocesses constitute “wholes.” All of this appears to afford a realistic explanation of wave-particle “duality,” the EPR and other quantum paradoxes, the hidden variable problem, the “collapse” of wave packets, and the wave interference mechanism with the ¦ ϕ ¦2 rule. (shrink)

I introduce a thin concept of ad hoc identity -- distinct from metaphysical accounts of either relative identity or absolute identity -- and an equally thin account of concepts and their content. According to the latter minimalist view of concepts, the content of a concept has behavioral consequences, and so content can be bounded if not determined by appeal to linguistic and psychological evidence. In the case of counting practices, this evidence suggests that the number concept depends on a notion (...) of identity at least as strong as ad hoc identity. In the context of nonrelativistic QM in particular, all of the counting procedures appealed to in the existing literature on nonindividuality are shown to involve ad hoc identity. I then show that Goyal Complementarity and the associated derivation of a strong symmetrization principle in QM can be understood in terms ad hoc identity. Specifically, persistence and non-persistence models of quantum processes are seen to be complementary in the sense that they involve two relations of ad hoc identity that occasionally overlap in empirically meaningful ways. Finally, I attempt to draw out consequences for theories of nonindividuality from the above conceptual analysis. The upshot is that counting and definite cardinality are incompatible with nonindividuality, and that none of the counting procedures cited for quantum phenomena offer positive support for an interpretation in terms of nonindividuals. (shrink)

Simon Saunders and David Wallace have proposed an attractive semantics for interpreting linguistic communities embedded in an Everettian multiverse. It provides a charitable interpretation of our ordinary talk about the future, and allows us to retain a principle of bivalence for propositions and to retain the law of excluded middle in the logic of propositions about the future. But difficulties arise when it comes to providing an appropriate account of the metaphysics of macroscopic objects and events. I evaluate various (...) metaphysical frameworks which might be combined with the Saunders–Wallace semantics. I conclude that the most appropriate metaphysics to underwrite the semantics renders Everettian quantum mechanics a theory of non-overlapping worlds. (shrink)

We describe here a series of experimental analogies between fluid mechanics and quantum mechanics recently discovered by a team of physicists. These analogies arise in droplet systems guided by a surface (or pilot) wave. We argue that these experimental facts put ancient theoretical work by Madelung on the analogy between fluid and quantum mechanics into new light. After re-deriving Madelung’s result starting from two basic fluid-mechanical equations (the Navier-Stokes equation and the continuity equation), we discuss the relation with (...) the de Broglie-Bohm theory. This allows to make a direct link with the droplet experiments. It is argued that the fluid-mechanical interpretation of quantum mechanics, if it can be extended to the general N-particle case, would have an advantage over the Bohm interpretation: it could rid Bohm’s theory of its strongly non-local character. (shrink)