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  1. Model Astrophysical Configurations with the Equation of State of Chaplygin Gas.Abdelghani Errehymy & Mohammed Daoud - 2019 - Foundations of Physics 49 (2):144-175.
    We use the Tolman–Oppenheimer–Volkoff equations for a Chaplygin type fluid to study, analytically and numerically, the global behavior of static solutions of spherically symmetric objects. Two possible regimes are especially investigated. The first one is the phantom regime in which the pressure module exceeds the energy density. In this case the equator is absent and all the solutions have the geometry of a truncated spheroid with the same kind of singularity. The second case is the normal regime for which we (...)
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  2.  11
    The Notion of Locality in Relational Quantum Mechanics.P. Martin-Dussaud, C. Rovelli & F. Zalamea - 2019 - Foundations of Physics 49 (2):96-106.
    The term ‘locality’ is used in different contexts with different meanings. There have been claims that relational quantum mechanics is local, but it is not clear then how it accounts for the effects that go under the usual name of quantum non-locality. The present article shows that the failure of ‘locality’ in the sense of Bell, once interpreted in the relational framework, reduces to the existence of a common cause in an indeterministic context. In particular, there is no need to (...)
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  3. Quaternion Algebra on 4D Superfluid Quantum Space-Time: Gravitomagnetism.Valeriy I. Sbitnev - 2019 - Foundations of Physics 49 (2):107-143.
    Gravitomagnetic equations result from applying quaternionic differential operators to the energy–momentum tensor. These equations are similar to the Maxwell’s EM equations. Both sets of the equations are isomorphic after changing orientation of either the gravitomagnetic orbital force or the magnetic induction. The gravitomagnetic equations turn out to be parent equations generating the following set of equations: the vorticity equation giving solutions of vortices with nonzero vortex cores and with infinite lifetime; the Hamilton–Jacobi equation loaded by the quantum potential. This equation (...)
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  4.  1
    A Local $$Psi $$-Epistemic Retrocausal Hidden-Variable Model of Bell Correlations with Wavefunctions in Physical Space.Indrajit Sen - 2019 - Foundations of Physics 49 (2):83-95.
    We construct a local \-epistemic hidden-variable model of Bell correlations by a retrocausal adaptation of the originally superdeterministic model given by Brans. In our model, for a pair of particles the joint quantum state \\rangle \) as determined by preparation is epistemic. The model also assigns to the pair of particles a factorisable joint quantum state \\rangle \) which is different from the prepared quantum state \\rangle \) and has an ontic status. The ontic state of a single particle consists (...)
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  5. A Bi-Directional Big Bang/Crunch Universe Within a Two-State-Vector Quantum Mechanics?Fritz W. Bopp - 2019 - Foundations of Physics 49 (1):53-62.
    A two boundary quantum mechanics incorporating a big bang/big crunch universe is carefully considered. After a short motivation of the concept we address the central question how a proposed a-causal quantum universe can be consistent with what is known about macroscopia and how it might find experimental support.
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  6.  1
    Cosmological Density Perturbations in Newtonian- and MONDian Gravity Scenario: A Symmetry-Based Approach.Amitava Choudhuri & Aritra Ganguly - 2019 - Foundations of Physics 49 (1):63-82.
    We investigate the evolution of linear density contrasts obtained with respect to a homogeneous spatially flat Friedman-Lemaître–Robertson–Walker background by solving the density contrast equations governed by Newtonian and MONDian force laws using symmetry-based approach. We find eight-parameter Lie group symmetries for the linear order density perturbation equation for the Newtonian case whereas the density contrast equation follows only one parameter Lie group symmetry in MONDian case. We use Lie symmetries to find the group invariant solutions from invariant curve condition. The (...)
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  7.  4
    Perturbations and Quantum Relaxation.Adithya Kandhadai & Antony Valentini - 2019 - Foundations of Physics 49 (1):1-23.
    We investigate whether small perturbations can cause relaxation to quantum equilibrium over very long timescales. We consider in particular a two-dimensional harmonic oscillator, which can serve as a model of a field mode on expanding space. We assume an initial wave function with small perturbations to the ground state. We present evidence that the trajectories are highly confined so as to preclude relaxation to equilibrium even over very long timescales. Cosmological implications are briefly discussed.
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  8.  2
    Analysis of Wallace’s Proof of the Born Rule in Everettian Quantum Mechanics II: Concepts and Axioms.André L. G. Mandolesi - 2019 - Foundations of Physics 49 (1):24-52.
    Having analyzed the formal aspects of Wallace’s proof of the Born rule, we now discuss the concepts and axioms upon which it is built. Justification for most axioms is shown to be problematic, and at times contradictory. Some of the problems are caused by ambiguities in the concepts used. We conclude the axioms are not reasonable enough to be taken as mandates of rationality in Everettian Quantum Mechanics. This invalidates the interpretation of Wallace’s result as meaning it would be rational (...)
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