Results for 'Phase space observables'

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  1.  11
    Phase Space Portraits of an Unresolved Gravitational Maxwell Demon.D. P. Sheehan, J. Glick, T. Duncan, J. A. Langton, M. J. Gagliardi & R. Tobe - 2002 - Foundations of Physics 32 (3):441-462.
    In 1885, during initial discussions of J. C. Maxwell's celebrated thermodynamic demon, Whiting (1) observed that the demon-like velocity selection of molecules can occur in a gravitationally bound gas. Recently, a gravitational Maxwell demon has been proposed which makes use of this observation [D. P. Sheehan, J. Glick, and J. D. Means, Found. Phys. 30, 1227 (2000)]. Here we report on numerical simulations that detail its microscopic phase space structure. Results verify the previously hypothesized mechanism of its paradoxical (...)
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  2.  6
    Coherent phase spaces. Semiclassical semantics.Sergey Slavnov - 2005 - Annals of Pure and Applied Logic 131 (1-3):177-225.
    The category of coherent phase spaces introduced by the author is a refinement of the symplectic “category” of A. Weinstein. This category is *-autonomous and thus provides a denotational model for Multiplicative Linear Logic. Coherent phase spaces are symplectic manifolds equipped with a certain extra structure of “coherence”. They may be thought of as “infinitesimal” analogues of familiar coherent spaces of Linear Logic. The role of cliques is played by Lagrangian submanifolds of ambient spaces. Physically, a symplectic manifold (...)
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  3.  5
    Normalized Observational Probabilities from Unnormalizable Quantum States or Phase-Space Distributions.Don N. Page - 2018 - Foundations of Physics 48 (7):827-836.
    Often it is assumed that a quantum state or a phase-space distribution must be normalizable. Here it is shown that even if it is not normalizable, one may be able to extract normalized observational probabilities from it.
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  4.  12
    Phase Space Portraits of an Unresolved Gravitational Maxwell Demon.Maxwell Demon, D. P. Sheehan, J. Glick, T. Duncan, J. A. Langton, M. J. Gagliardi & R. Tobe - 2002 - Foundations of Physics 32 (3):441-462.
    In 1885, during initial discussions of J. C. Maxwell's celebrated thermodynamic demon, Whiting(1) observed that the demon-like velocity selection of molecules can occur in a gravitationally bound gas. Recently, a gravitational Maxwell demon has been proposed which makes use of this observation [D. P. Sheehan, J. Glick, and J. D. Means, Found. Phys. 30, 1227 (2000)]. Here we report on numerical simulations that detail its microscopic phase space structure. Results verify the previously hypothesized mechanism of its paradoxical behavior. (...)
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  5.  10
    On Nonlinear Quantum Mechanics, Noncommutative Phase Spaces, Fractal-Scale Calculus and Vacuum Energy.Carlos Castro - 2010 - Foundations of Physics 40 (11):1712-1730.
    A (to our knowledge) novel Generalized Nonlinear Schrödinger equation based on the modifications of Nottale-Cresson’s fractal-scale calculus and resulting from the noncommutativity of the phase space coordinates is explicitly derived. The modifications to the ground state energy of a harmonic oscillator yields the observed value of the vacuum energy density. In the concluding remarks we discuss how nonlinear and nonlocal QM wave equations arise naturally from this fractal-scale calculus formalism which may have a key role in the final (...)
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  6.  6
    The Equiareal Archimedean Synchronization Method of the Quantum Symplectic Phase Space: II. Circle-Valued Moment Map, Integrality, and Symplectic Abelian Shadows.Elias Zafiris - 2022 - Foundations of Physics 52 (2):1-32.
    The quantum transition probability assignment is an equiareal transformation from the annulus of symplectic spinorial amplitudes to the disk of complex state vectors, which makes it equivalent to the equiareal projection of Archimedes. The latter corresponds to a symplectic synchronization method, which applies to the quantum phase space in view of Weyl’s quantization approach involving an Abelian group of unitary ray rotations. We show that Archimedes’ method of synchronization, in terms of a measure-preserving transformation to an equiareal disk, (...)
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  7.  6
    Born’s Reciprocal Gravity in Curved Phase-Spaces and the Cosmological Constant.Carlos Castro - 2012 - Foundations of Physics 42 (8):1031-1055.
    The main features of how to build a Born’s Reciprocal Gravitational theory in curved phase-spaces are developed. By recurring to the nonlinear connection formalism of Finsler geometry a generalized gravitational action in the 8D cotangent space (curved phase space) can be constructed involving sums of 5 distinct types of torsion squared terms and 2 distinct curvature scalars ${\mathcal{R}}, {\mathcal{S}}$ which are associated with the curvature in the horizontal and vertical spaces, respectively. A Kaluza-Klein-like approach to the (...)
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  8.  1
    The Extended Relativity Theory in Born-Clifford Phase Spaces with a Lower and Upper Length Scales and Clifford Group Geometric Unification.Carlos Castro - 2005 - Foundations of Physics 35 (6):971-1041.
    We construct the Extended Relativity Theory in Born-Clifford-Phase spaces with an upper R and lower length λ scales (infrared/ultraviolet cutoff). The invariance symmetry leads naturally to the real Clifford algebra Cl (2, 6, R) and complexified Clifford Cl C (4) algebra related to Twistors. A unified theory of all Noncommutative branes in Clifford-spaces is developed based on the Moyal-Yang star product deformation quantization whose deformation parameter involves the lower/upper scale $$(\hbar \lambda / R)$$. Previous work led us to show (...)
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  9.  11
    Pseudo-classical phase space description of the relativistic electron.G. C. Sherry - 1989 - Foundations of Physics 19 (6):733-741.
    Several versions exist of pseudo-classical models of the electron using Grassmann variables. Most of these require additional constraints on the variables, and it is these which, when quantized, lead to Dirac's equation. In addition, the Grassmann variables do not have physical interpretations. In this article a model is constructed which does not require constraints and in which the Grassmann variables can be interpreted as observables. Dirac's equation is obtained directly from quantization.
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  10.  4
    On the nonclassical character of the phase-space representations of quantum mechanics.W. Guz - 1985 - Foundations of Physics 15 (2):121-128.
    The quasiclassical representations of quantum theory, generalizing the concept of a phase-space representation of quantum mechanics, are studied with particular emphasis on some questions connected with the Jordan structure of the classical and quantum algebras of observables. A generalized version of the theorem of Gleason, Kahane, and Zelazko is used to establish some nonclassical features of these representations.
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  11.  2
    Function moves biomolecular condensates in phase space.Marina Feric & Tom Misteli - 2022 - Bioessays 44 (5):2200001.
    Phase separation underlies the formation of biomolecular condensates. We hypothesize the cellular processes that occur within condensates shape their structural features. We use the example of transcription to discuss structure–function relationships in condensates. Various types of transcriptional condensates have been reported across the evolutionary spectrum in the cell nucleus as well as in mitochondrial and bacterial nucleoids. In vitro and in vivo observations suggest that transcriptional activity of condensates influences their supramolecular structure, which in turn affects their function. Condensate (...)
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  12.  5
    On the Complementarity of the Quadrature Observables.Pekka Lahti & Juha-Pekka Pellonpää - 2010 - Foundations of Physics 40 (9-10):1419-1428.
    In this paper we investigate the coupling properties of pairs of quadrature observables, showing that, apart from the Weyl relation, they share the same coupling properties as the position-momentum pair. In particular, they are complementary. We determine the marginal observables of a covariant phase space observable with respect to an arbitrary rotated reference frame, and observe that these marginal observables are unsharp quadrature observables. The related distributions constitute the Radon transform of a phase (...)
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  13.  1
    Space Localization of the Photon.Roberto Beneduci & Franklin Schroeck - 2019 - Foundations of Physics 49 (6):561-576.
    Starting from the phase space representation of quantum mechanics we provide an Euclidean system of covariance for the photon. In particular, we consider systems with the Poincaré group as the symmetry group and use a standard procedure in order to build a phase space and a localization observable on the phase space. Then we focus on the massless representations of the Poincaré group that we use to build a space localization observable for the (...)
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  14.  16
    Spaces of Possibility.Timothy Williamson - 2018 - Royal Institute of Philosophy Supplement 82:189-204.
    We care not just how things are but how they could have been otherwise – about possibility and necessity as well as actuality. Many philosophers regard such talk as beyond the reach of respectable science, since observation tells us how things are but not how they could have been otherwise. I argue that, on the contrary, such criticisms are ill-founded: possibility and necessity are studied in natural science, for example through phase spaces, abstract mathematical representations of the possible states (...)
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  15.  10
    On the Relation Between Gauge and Phase Symmetries.Gabriel Catren - 2014 - Foundations of Physics 44 (12):1317-1335.
    We propose a group-theoretical interpretation of the fact that the transition from classical to quantum mechanics entails a reduction in the number of observables needed to define a physical state and \ to \ or \ in the simplest case). We argue that, in analogy to gauge theories, such a reduction results from the action of a symmetry group. To do so, we propose a conceptual analysis of formal tools coming from symplectic geometry and group representation theory, notably Souriau’s (...)
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  16.  4
    Cognition versus Constitution of Objects: From Kant to Modern Physics.Peter Mittelstaedt - 2009 - Foundations of Physics 39 (7):847-859.
    Classical mechanics in phase space as well as quantum mechanics in Hilbert space lead to states and observables but not to objects that may be considered as carriers of observable quantities. However, in both cases objects can be constituted as new entities by means of invariance properties of the theories in question. We show, that this way of reasoning has a long history in physics and philosophy and that it can be traced back to the transcendental (...)
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  17.  3
    Формування стратегії розвитку підприємства на основі динамічного space-аналізу.Valeriy Balan & Inna Tymchenko - 2016 - Схід 4 (144):5-16.
    Development strategy of using modern portfolio theory focused on the short term. However, macroeconomic uncertainty and geopolitical environment makes their use ineffective. And challenge is to provide a reasonable balance between the short and long term profitability. Another issue, which is to some extent related to the previous observation is the absence in most matrices strategic recommendations for non-standard "behavior" of business units with dynamic analysis. This applies to the use of a relatively new tool matrix approach to development strategies (...)
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  18.  4
    Quantum Theory Without Hilbert Spaces.C. Anastopoulos - 2001 - Foundations of Physics 31 (11):1545-1580.
    Quantum theory does not only predict probabilities, but also relative phases for any experiment, that involves measurements of an ensemble of systems at different moments of time. We argue, that any operational formulation of quantum theory needs an algebra of observables and an object that incorporates the information about relative phases and probabilities. The latter is the (de)coherence functional, introduced by the consistent histories approach to quantum theory. The acceptance of relative phases as a primitive ingredient of any quantum (...)
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  19.  4
    Coexistence of multiple periodic and chaotic regimes in biochemical oscillations with phase shifts.I. M. de la Fuente, L. Martinez, J. M. Aguirregabiria & J. Veguillas - 1998 - Acta Biotheoretica 46 (1):37-51.
    The numerical study of a glycolytic model formed by a system of three delay differential equations reveals a multiplicity of stable coexisting states: birhythmicity, trirhythmicity, hard excitation and quasiperiodic with chaotic regimes. For different initial functions in the phase space one may observe the coexistence of two different quasiperiodic motions, the existence of a stable steady state with a stable torus, and the existence of a strange attractor with different stable regimes (chaos with torus, chaos with bursting motion, (...)
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  20.  7
    Berry phase and quantum structure.Holger Lyre - 2014 - Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics 48:45-51.
    The paper aims to spell out the relevance of the Berry phase in view of the question what the minimal mathematical structure is that accounts for all observable quantum phenomena. The question is both of conceptual and of ontological interest. While common wisdom tells us that the quantum structure is represented by the structure of the projective Hilbert space, the appropriate structure rich enough to account for the Berry phase is the U(1) bundle over that projective (...). The Berry phase is ultimately rooted in the curvature of this quantum bundle, it cannot be traced back to the Hamiltonian dynamics alone. This motivates the ontological claim in the final part of the paper that, if one strives for a realistic understanding of quantum theory including the Berry phase, one should adopt a form of ontic structural realism. (shrink)
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  21.  11
    The Quantum Phase Problem: Steps Toward a Resolution. [REVIEW]Gilad Gour - 2002 - Foundations of Physics 32 (6):907-926.
    Defining the observable φ canonically conjugate to the number observable N has long been an open problem in quantum theory. The problem stems from the fact that N is bounded from below. In a previous work we have shown how to define the absolute phase observable Φ≡|φ| by suitably restricting the Hilbert space of x and p like variables. Here we show that also from the classical point of view, there is no rigorous definition for the phase (...)
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  22.  7
    Physical uniformities on the state space of nonrelativisitic quantum mechanics.Reinhard Werner - 1983 - Foundations of Physics 13 (8):859-881.
    Uniformities describing the distinguishability of states and of observables are discussed in the context of general statistical theories and are shown to be related to distinguished subspaces of continuous observables and states, respectively. The usual formalism of quantum mechanics contains no such physical uniformity for states. Using recently developed tools of quantum harmonic analysis, a natural one-to-one correspondence between continuous subspaces of nonrelativistic quantum and classical mechanics is established, thus exhibiting a close interrelation between physical uniformities for quantum (...)
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  23. Hilbert Space dimensions 3, 4, 5.Paul Merriam, Daniel Huber & Bob Hanlon - forthcoming - Foundations of Physics:6.
    This is a pdf of a Mathematica calculation that supplements the paper "Presentist Fragmentalism and Quantum Mechanics" forthcoming in Foundations of Physics. In that paper the Born rule (or at least a progenitor) is derived from experimental conditions on the mutual observations of two fragments. In this pdf the experimental conditions are applied to Hilbert space dimensions 3, 4, and 5. It turns out each of these have a 1-dimensional solution space which, it is hoped, can be interpretated (...)
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  24.  10
    Learning Words Via Reading: Contextual Diversity, Spacing, and Retrieval Effects in Adults.Ascensión Pagán & Kate Nation - 2019 - Cognitive Science 43 (1):e12705.
    We examined whether variations in contextual diversity, spacing, and retrieval practice influenced how well adults learned new words from reading experience. Eye movements were recorded as adults read novel words embedded in sentences. In the learning phase, unfamiliar words were presented either in the same sentence repeated four times (same context) or in four different sentences (diverse context). Spacing was manipulated by presenting the sentences under distributed or non‐distributed practice. After learning, half of the participants were asked to retrieve (...)
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  25.  3
    Embedding of the classical into the quantum description of photons.M. Enderle & H. Neumann - 1994 - Foundations of Physics 24 (10):1415-1424.
    The macroscopic properties of a many-particle quantum system are revealed by an embedding of the macroscopic classical into the microscopic quantum description of the system. Such an embedding is based on the assumption that the experiments to which the classical theory applies may also be described quantum mechanically. It results from the existence of an injective trajectory observable. For photon quantum systems with a finite number of modes an embedding is explicitly constructed using the well- known phase space (...)
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  26. The Kochen - Specker theorem in quantum mechanics: a philosophical comment (part 1).Vasil Penchev - 2013 - Philosophical Alternatives 22 (1):67-77.
    Non-commuting quantities and hidden parameters – Wave-corpuscular dualism and hidden parameters – Local or nonlocal hidden parameters – Phase space in quantum mechanics – Weyl, Wigner, and Moyal – Von Neumann’s theorem about the absence of hidden parameters in quantum mechanics and Hermann – Bell’s objection – Quantum-mechanical and mathematical incommeasurability – Kochen – Specker’s idea about their equivalence – The notion of partial algebra – Embeddability of a qubit into a bit – Quantum computer is not Turing (...)
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  27.  1
    Uncertainty measures and uncertainty relations for angle observables.Ernst Breitenberger - 1985 - Foundations of Physics 15 (3):353-364.
    Uncertainty measures must not depend on the choice of origin of the measurement scale; it is therefore argued that quantum-mechanical uncertainty relations, too, should remain invariant under changes of origin. These points have often been neglected in dealing with angle observables. Known measures of location and uncertainty for angles are surveyed. The angle variance angv {ø} is defined and discussed. It is particularly suited to the needs of quantum theory, because of its affinity to the Hilbert space metric, (...)
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  28.  4
    How Problematic is the Near-Euclidean Spatial Geometry of the Large-Scale Universe?M. Holman - 2018 - Foundations of Physics 48 (11):1617-1647.
    Modern observations based on general relativity indicate that the spatial geometry of the expanding, large-scale Universe is very nearly Euclidean. This basic empirical fact is at the core of the so-called “flatness problem”, which is widely perceived to be a major outstanding problem of modern cosmology and as such forms one of the prime motivations behind inflationary models. An inspection of the literature and some further critical reflection however quickly reveals that the typical formulation of this putative problem is fraught (...)
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  29.  8
    How macrostates come about?Marton Gomori, Balazs Gyenis & Gábor Hofer-Szabó - unknown
    This paper is a further consideration of Hemmo and Shenker’s ideas about the proper conceptual characterization of macrostates in statistical mechanics. We provide two formulations of how macrostates come about as elements of certain partitions of the system’s phase space imposed on by the interaction between the system and an observer, and we show that these two formulations are mathematically equivalent. We also reflect on conceptual issues regarding the relationship of macrostates to distinguishability, thermodynamic regularity, observer dependence, and (...)
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  30.  30
    First-class constraints generate gauge transformations in electromagnetism (reply to Pitts).Oliver Pooley & David Wallace - manuscript
    Brian Pitts has recently claimed to show via straightforward calculation that, at least in the case of Hamiltonian electromagnetism, an arbitrary first-class constraint ``generates not a gauge transformation, but a bad physical change'' (Annals of Physics 351 (2014) pp.382-406; arXiv:1310.2756). We show, via a straightforward calculation, that a transformation generated by an arbitrary first-class constraint relates gauge-equivalent phase space points, vindicating orthodoxy. Pitts, however, is primarily concerned with transformations of entire histories, rather than of instantaneous states. We show (...)
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  31.  11
    New Perspectives on Spontaneous Brain Activity: Dynamic Networks and Energy Matter.Arturo Tozzi, Marzieh Zare & April A. Benasich - 2016 - Frontiers in Human Neuroscience 10:147690.
    Spontaneous brain activity has received increasing attention as demonstrated by the exponential rise in the number of published papers on this topic over the last thirty years. Such “intrinsic” brain activity, generated in the absence of an explicit task, is frequently associated with resting-state or default-mode networks. The focus on characterizing spontaneous brain activity promises to shed new light on questions concerning the structural and functional architecture of the brain and how they are related to “mind”. However, many critical questions (...)
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  32.  17
    Three denials of time in the interpretation of canonical gravity.Karim P. Y. Thébault - 2012 - Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics 43 (4):277-294.
    The analysis of the temporal structure of canonical general relativity and the connected interpretational questions with regard to the role of time within the theory both rest upon the need to respect the fundamentally dual role of the Hamiltonian constraints found within the formalism. Any consistent philosophical approach towards the theory must pay dues to the role of these constraints in both generating dynamics, in the context of phase space, and generating unphysical symmetry transformations, in the context of (...)
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  33.  4
    Quantum Phase Space from Schwinger’s Measurement Algebra.P. Watson & A. J. Bracken - 2014 - Foundations of Physics 44 (7):762-780.
    Schwinger’s algebra of microscopic measurement, with the associated complex field of transformation functions, is shown to provide the foundation for a discrete quantum phase space of known type, equipped with a Wigner function and a star product. Discrete position and momentum variables label points in the phase space, each taking \(N\) distinct values, where \(N\) is any chosen prime number. Because of the direct physical interpretation of the measurement symbols, the phase space structure is (...)
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  34.  7
    Naturalizing Physics. Or, embedding physics in the historicity and materiality of the living.Giuseppe Longo - unknown
    The rich blend of theories and experiences that made the history of physics possible still now enlightens the scientific method. We stress the need to learn from this method the force of making its principles explicit, while developing a rich diversity of theories, which are often incompatible. Unity is preserved by common founding principles and their mathematical form, such as the understanding of conservation properties (energy, momentum etc.) in terms of symmetries. When moving from the inert to the living state (...)
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  35.  3
    The classical limit of a state on the Weyl algebra.Benjamin H. Feintzeig - unknown
    This paper considers states on the Weyl algebra of the canonical commutation relations over the phase space R^{2n}. We show that a state is regular iff its classical limit is a countably additive Borel probability measure on R^{2n}. It follows that one can "reduce" the state space of the Weyl algebra by altering the collection of quantum mechanical observables so that all states are ones whose classical limit is physical.
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  36.  15
    Symplectic Reduction and the Problem of Time in Nonrelativistic Mechanics.Karim P. Y. Thébault - 2012 - British Journal for the Philosophy of Science 63 (4):789-824.
    Symplectic reduction is a formal process through which degeneracy within the mathematical representations of physical systems displaying gauge symmetry can be controlled via the construction of a reduced phase space. Typically such reduced spaces provide us with a formalism for representing both instantaneous states and evolution uniquely and for this reason can be justifiably afforded the status of fun- damental dynamical arena - the otiose structure having been eliminated from the original phase space. Essential to the (...)
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  37.  4
    The Loss of Coherence in Quantum Cosmology.Katinka Ridderbos - 1998 - Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics 30 (1):41-60.
    I analyse two different methods for the retrieval of a classical notion of spacetime from the theory of quantum cosmology in terms of the different means they employ to bring about the necessary loss of coherence. One method employs a direct coarse graining of the appropriate phase space, whereas the other method is based on decohering the system by the interaction with an environment. Although these methods are equivalent on a phenomenological level, I argue that conceptually the decoherence (...)
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  38.  6
    From Classical to Quantum Models: The Regularising Rôle of Integrals, Symmetry and Probabilities.Jean-Pierre Gazeau - 2018 - Foundations of Physics 48 (11):1648-1667.
    In physics, one is often misled in thinking that the mathematical model of a system is part of or is that system itself. Think of expressions commonly used in physics like “point” particle, motion “on the line”, “smooth” observables, wave function, and even “going to infinity”, without forgetting perplexing phrases like “classical world” versus “quantum world”.... On the other hand, when a mathematical model becomes really inoperative in regard with correct predictions, one is forced to replace it with a (...)
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  39.  17
    Can quantum mechanics be formulated as a classical probability theory?Leon Cohen - 1966 - Philosophy of Science 33 (4):317-322.
    It is shown that quantum mechanics cannot be formulated as a stochastic theory involving a probability distribution function of position and momentum. This is done by showing that the most general distribution function which yields the proper quantum mechanical marginal distributions cannot consistently be used to predict the expectations of observables if phase space integration is used. Implications relating to the possibility of establishing a "hidden" variable theory of quantum mechanics are discussed.
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  40.  5
    Flows into inflation: An effective field theory approach.Feraz Azhar & David I. Kaiser - 2018 - Physical Review D 98 (6).
    We analyze the flow into inflation for generic "single-clock" systems, by combining an effective field theory approach with a dynamical-systems analysis. In this approach, we construct an expansion for the potential-like term in the effective action as a function of time, rather than specifying a particular functional dependence on a scalar field. We may then identify fixed points in the effective phase space for such systems, order-by-order, as various constraints are placed on the Mth time derivative of the (...)
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  41.  9
    Complementarity in Classical Dynamical Systems.Harald Atmanspacher - 2006 - Foundations of Physics 36 (2):291-306.
    The concept of complementarity, originally defined for non-commuting observables of quantum systems with states of non-vanishing dispersion, is extended to classical dynamical systems with a partitioned phase space. Interpreting partitions in terms of ensembles of epistemic states (symbols) with corresponding classical observables, it is shown that such observables are complementary to each other with respect to particular partitions unless those partitions are generating. This explains why symbolic descriptions based on an ad hoc partition of an (...)
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  42.  9
    Dual Relativistic Quantum Mechanics I.Tepper L. Gill, Gonzalo Ares de Parga, Trey Morris & Mamadou Wade - 2022 - Foundations of Physics 52 (4):1-21.
    It was shown in Dirac A117, 610; A118, 351, 1928) that the ultra-violet divergence in quantum electrodynamics is caused by a violation of the time-energy uncertainly relationship, due to the implicit assumption of infinitesimal time information. In Wheeler et al. it was shown that Einstein’s special theory of relativity and Maxwell’s field theory have mathematically equivalent dual versions. The dual versions arise from an identity relating observer time to proper time as a contact transformation on configuration space, which leaves (...)
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  43.  2
    Quantum Prey–Predator Dynamics: A Gaussian Ensemble Analysis.A. E. Bernardini & O. Bertolami - 2023 - Foundations of Physics 53 (3):1-11.
    Quantum frameworks for modeling competitive ecological systems and self-organizing structures have been investigated under multiple perspectives yielded by quantum mechanics. These comprise the description of the phase-space prey–predator competition dynamics in the framework of the Weyl–Wigner quantum mechanics. In this case, from the classical dynamics described by the Lotka–Volterra (LV) Hamiltonian, quantum states convoluted by statistical gaussian ensembles can be analytically evaluated. Quantum modifications on the patterns of equilibrium and stability of the prey–predator dynamics can then be identified. (...)
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  44.  13
    The loss of coherence in quantum cosmology.Katinka Ridderbos - 1999 - Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics 30 (1):41-60.
    I analyse two different methods for the retrieval of a classical notion of spacetime from the theory of quantum cosmology in terms of the different means they employ to bring about the necessary loss of coherence. One method employs a direct coarse graining of the appropriate phase space, whereas the other method is based on decohering the system by the interaction with an environment. Although these methods are equivalent on a phenomenological level, I argue that conceptually the decoherence (...)
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  45.  12
    Models, confirmation, and chaos.Jeffrey Koperski - 1998 - Philosophy of Science 65 (4):624-648.
    The use of idealized models in science is by now well-documented. Such models are typically constructed in a “top-down” fashion: starting with an intractable theory or law and working down toward the phenomenon. This view of model-building has motivated a family of confirmation schemes based on the convergence of prediction and observation. This paper considers how chaotic dynamics blocks the convergence view of confirmation and has forced experimentalists to take a different approach to model-building. A method known as “phase (...)
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  46. Dealing with the Unexpected.John Collier - unknown
    Typically, we think of both artificial and natural computing devices as following rules that allow them to alter their behaviour (output) according to their environment (input). This approach works well when the environment and goals are well defined and regular. However, 1) the search time for appropriate solutions quickly becomes intractable when the input is not fairly regular, and 2) responses may be required that are not computable, either in principle, or given the computational resources available to the system. It (...)
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  47.  2
    Quantum Ontology in the Light of Gauge Theories.Gabriel Catren - unknown
    We propose the conjecture according to which the fact that quantum mechanics does not admit sharp value attributions to both members of a complementary pair of observables can be understood in the light of the symplectic reduction of phase space in constrained Hamiltonian systems. In order to unpack this claim, we propose a quantum ontology based on two independent postulates, namely the phase postulate and the quantum postulate. The phase postulate generalizes the gauge correspondence between (...)
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  48. Particles and the Perversely Philosophical Schoolchild: Rigid Designation, Haecceitism and Statistics.Anna Maidens - 1998 - Teorema: International Journal of Philosophy 17 (1):75-87.
    In this paper, I want to draw attention to a connection between rigid designation with its consequence that we are able to stipulate worlds and haecceitism, the doctrine that we have possible worlds alike in all qualitative features which nonetheless are metaphysically different, in that two individuals can have all their qualitative features swapped while remaining the same individuals. I shall argue that stipulation leads to haecceitism, which in turn depends upon commitment to haecceity ("primitive thisness"). Haecceitism is, I claim, (...)
     
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    Passage of time in a planck scale rooted local inertial structure.Joy Christian - unknown
    It is argued that the `problem of time' in quantum gravity necessitates a refinement of the local inertial structure of the world, demanding a replacement of the usual Minkowski line element by a 4+2n dimensional pseudo-Euclidean line element, with the extra 2n being the number of internal phase space dimensions of the observed system. In the refined structure, the inverse of the Planck time takes over the role of observer-independent conversion factor usually played by the speed of light, (...)
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    An “Anti-Gleason” Phenomenon and Simultaneous Measurements in Classical Mechanics.Michael Entov, Leonid Polterovich & Frol Zapolsky - 2007 - Foundations of Physics 37 (8):1306-1316.
    We report on an “anti-Gleason” phenomenon in classical mechanics: in contrast with the quantum case, the algebra of classical observables can carry a non-linear quasi-state, a monotone functional which is linear on all subspaces generated by Poisson-commuting functions. We present an example of such a quasi-state in the case when the phase space is the 2-sphere. This example lies in the intersection of two seemingly remote mathematical theories—symplectic topology and the theory of topological quasi-states. We use this (...)
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