The One, the Many, and the Quantum

The problem of understanding quantum mechanics is in large measure the problem of finding appropriate ways of thinking about the spatial and temporal aspects of the physical world. The standard, substantival, set-theoretic conception of space is inconsistent with quantum mechanics, and so is the doctrine of local realism, the principle of local causality, and the mathematical physicist's golden calf, determinism. The said problem is made intractable by our obtruding onto the physical world a theoretical framework that is more detailed than the physical world. This framework portraits space and time as infinitely and intrinsically differentiated, whereas the physical world is only finitely differentiated spacewise and timewise, namely to the extent that spatiotemporal relations and distinctions are warranted by facts. This has the following consequences: (i) The contingent properties of the physical world, including the times at which they are possessed, are indefinite and extrinsic. (ii) We cannot think of reality as being built "from the bottom up", out of locally instantiated physical properties. Instead we must conceive of the physical world as being built "from the top down": By entering into a multitude of spatial relations with itself, "existence itself" takes on both the aspect of a spatially differentiated world and the aspect of a multiplicity of formless relata, the fundamental particles. At the root of our interpretational difficulties is the "cookie cutter paradigm", according to which the world's synchronic multiplicity is founded on the introduction of surfaces that carve up space in the manner of three-dimensional cookie cutters. The neurophysiological underpinnings of this insidious notion are discussed.Comment: 47 pages, LaTeX2e with epsfig (2 figures

Two theories of decoherence

Theories of decoherence come in two flavors---Platonic and Aristotelian. Platonists grant ontological primacy to the concepts and mathematical symbols by which we describe or comprehend the physical world. Aristotelians grant it to the physical world. The significance one attaches to the phenomenon of decoherence depends on the school to which one belongs. The debate about the significance of quantum states has for the most part been carried on between Platonists and Kantians, who advocate an epistemic interpretation, with Aristotelians caught in the crossfire. For the latter, quantum states are neither states of Nature nor states of knowledge. The real issue is not the kind of reality that we should attribute to quantum states but the reality of the spatial and temporal distinctions that we make. Once this is recognized, the necessity of attributing ontological primacy to facts becomes obvious, the Platonic stance becomes inconsistent, and the Kantian point of view becomes unnecessarily restrictive and unilluminating.Comment: 12 pages, LaTeX2

A space for the quantum world

Epistemic interpretations of quantum mechanics fail to address the puzzle posed by the occurrence of probabilities in a fundamental physical theory. This is a puzzle about the physical world, not a puzzle about our relation to the physical world. Its solution requires a new concept of physical space, presented in this article. An examination of how the mind and the brain construct the phenomenal world reveals the psychological and neurobiological reasons why we think about space in ways that are inadequate to the physical world. The resulting notion that space is an intrinsically partitioned expanse has up to now stood in the way of a consistent ontological interpretation.Comment: 11 pages, LaTeX2

"B" is for Bohr

It is suggested that the "B" in QBism rightfully stands for Bohr. The paper begins by explaining why Bohr seems obscure to most physicists. Having identified the contextuality of physical quantities as Bohr's essential contribution to Kant's theory of science, it outlines the latter, its proper contextuality (human experience), and its decontextualization. In order to preserve the decontextualization achieved by Kant's theory, Bohr seized on quantum phenomena as the principal referents of atomic physics, all the while keeping the universal context of human experience at the center of his philosophy. QBism, through its emphasis on the individual experiencing subject, brings home the intersubjective constitution of objectivity more forcefully than Bohr ever did. If measurements are irreversible and outcomes definite, it is because the experiences of each subject are irreversible and definite. Bohr's insights, on the other hand, are exceedingly useful in clarifying the QBist position, attenuating its excesses, and enhancing its internal consistency.Comment: 38 pages, to appear in the combined Proceedings of the Workshops on Meaning and Structure of Quantum Mechanics at Buenos Aires (2016 and 2019

The Pondicherry interpretation of quantum mechanics

This article presents a novel interpretation of quantum mechanics. It extends the meaning of ``measurement'' to include all property-indicating facts. Intrinsically space is undifferentiated: there are no points on which a world of locally instantiated physical properties could be built. Instead, reality is built on facts, in the sense that the properties of things are extrinsic, or supervenient on property-indicating facts. The actual extent to which the world is spatially and temporally differentiated (that is, the extent to which spatiotemporal relations and distinctions are warranted by the facts) is necessarily limited. Notwithstanding that the state vector does nothing but assign probabilities, quantum mechanics affords a complete understanding of the actual world. If there is anything that is incomplete, it is the actual world, but its incompleteness exists only in relation to a conceptual framework that is more detailed than the actual world. Two deep-seated misconceptions are responsible for the interpretational difficulties associated with quantum mechanics: the notion that the spatial and temporal aspects of the world are adequately represented by sets with the cardinality of the real numbers, and the notion of an instantaneous state that evolves in time. The latter is an unwarranted (in fact, incoherent) projection of our apparent ``motion in time'' into the world of physics. Equally unwarranted, at bottom, is the use of causal concepts. There nevertheless exists a ``classical'' domain in which language suggestive of nomological necessity may be used. Quantum mechanics not only is strictly consistent with the existence of this domain but also presupposes it in several ways.Comment: TeX, 38 pages, forthcoming in American Journal of Physics under the title ``What quantum mechanics is trying to tell us'', v2: revised submission, v3: changes in proo

Unveiled reality: comment on d'Espagnat's note on measurement

According to d'Espagnat we must choose between nonlinear breaks in quantum state evolution and weak objectivity. In this comment it is shown that this choice is forced on us by an inconsistent pseudo-realistic interpretation of quantum states. A strongly objective one-world interpretation of linear quantum mechanics is presented. It is argued that the weak objectivity favored by d'Espagnat is, in fact, inconsistent with quantum mechanics.Comment: Comment on quant-ph/0101141, 13 pages, LaTeX2

Is the end in sight for theoretical pseudophysics?

The question of what ontological message (if any) is encoded in the formalism of contemporary physics is, to say the least, controversial. The reasons for this state of affairs are psychological and neurobiological. The processes by which the visual world is constructed by our minds, predispose us towards concepts of space, time, and substance that are inconsistent with the spatiotemporal and substantial aspects of the quantum world. In the first part of this chapter, the latter are extracted from the quantum formalism. The nature of a world that is fundamentally and irreducibly described by a probability algorithm is determined. The neurobiological processes responsible for the mismatch between our "natural" concepts of space, time, and substance and the corresponding aspects of the quantum world are discussed in the second part. These natural concepts give rise to pseudoproblems that foil our attempts to make ontological sense of quantum mechanics. If certain psychologically motivated but physically unwarranted assumptions are discarded (in particular our dogged insistence on obtruding upon the quantum world the intrinsically and completely differentiated spatiotemporal background of classical physics), we are in a position to see why our fundamental physical theory is a probability algorithm, and to solve the remaining interpretational problems.Comment: To appear in a volume edited by V. Krasnoholovets and F. Columbus and published by Nova Science; 26 page

Reflections on the Spatiotemporal Aspects of the Quantum World

The proper resolution of the so-called measurement problem requires a "top-down" conception of the quantum world that is opposed to the usual "bottom-up" conception, which builds on an intrinsically and maximally differentiated manifold. The key to that problem is that the fuzziness of a variable can manifest itself only to the extent that less fuzzy variables exist. Inasmuch as there is nothing less fuzzy than the metric, this argues against a quantum-gravity phenomenology and suggests that a quantum theory of gravity is something of a contradiction in terms - a theory that would make it possible to investigate the physics on scales that do not exist, or to study the physical consequences of a fuzziness that has no physical consequences, other than providing a natural cutoff for the quantum field theories of particle physics.Comment: Invited talk at the First Meeting on the Interface of Gravitational and Quantum Realms held at IUCAA, Pune (India), December 17--21, 2001. To appear in Mod. Phys. Lett. A. 17 pages. LaTeX2

The Quantum Mechanics of Being and Its Manifestation

How can quantum mechanics be (i) the fundamental theoretical framework of contemporary physics and (ii) a probability calculus that presupposes the events to which, and on the basis of which, it assigns probabilities? The question is answered without invoking knowledge or observers, by interpreting the necessary distinction between two kinds of physical quantities - unconditionally definite quantities and quantities that have values only if they are measured - as a distinction between the manifested world and its manifestation.Comment: Published (without the Appendix) in Cosmology (Vol. 24, April 2, 2016): http://cosmology.com/ConsciousnessUniverse3.html. While the published paper touches on various ways in which quantum mechanics does not have to do with consciousness, the Appendix concerns what quantum mechanics has to do with consciousness. 9 pages, 0 figures, PD

Why the wave function, of all things?

There are reasons to doubt that making sense of the wave function (other than as a probability algorithm) will help with the project of making sense of quantum mechanics. The consistency of the quantum-mechanical correlation laws with the existence of their correlata is demonstrated. The demonstration makes use of the fact (which is implied by the indeterminacy principle) that physical space is not partitioned "all the way down," and it requires that the eigenvalue-eigenstate link be replaced by a different interpretive principle, whose implications are explored.Comment: 12 pages, contribution to an online workshop on the meaning of the wave function, slightly revise