8 found
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  1.  23
    A Velocity Field and Operator for Spinning Particles in (Nonrelativistic) Quantum Mechanics.Giovanni Salesi & Erasmo Recami - 1998 - Foundations of Physics 28 (5):763-773.
    Starting from the formal expressions of the hydrodynamical (or “local”) quantities employed in the applications of Clifford algebras to quantum mechanics, we introduce—in terms of the ordinary tensorial language—a new definition for the field of a generic quantity. By translating from Clifford into tensor algebra, we also propose a new (nonrelativistic) velocity operator for a spin- ${\frac{1}{2}}$ particle. This operator appears as the sum of the ordinary part p/m describing the mean motion (the motion of the center-of-mass), and of a (...)
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  2.  67
    Superluminal Motions? A Bird's-Eye View of the Experimental Situation.Erasmo Recami - 2001 - Foundations of Physics 31 (7):1119-1135.
    In this article, after a theoretical introduction and a sketch of some related long-standing predictions, a bird's-eye view is presented—with the help of nine figures—of the various experimental sectors of physics in which Superluminal motions seem to appear (thus contributing support to those past predictions). In particular, a panorama is presented of the experiments with evanescent waves and/or tunnelling photons, and with the “localized Superluminal solutions” to the Maxwell equations (like the so-called X-shaped beams). The present review is brief, but (...)
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  3.  23
    Tachyon Kinematics and Causality: A Systematic Thorough Analysis of the Tachyon Causal Paradoxes. [REVIEW]Erasmo Recami - 1987 - Foundations of Physics 17 (3):239-296.
    The chronological order of the events along a spacelike path is not invariant under Lorentz transformations, as is well known. This led to an early conviction that tachyons would give rise to causal anomalies. A relativistic version of the Stückelberg-Feynman “switching procedure” (SWP) has been invoked as the suitable tool to eliminate those anomalies. The application of the SWP does eliminate the motions backwards in time, but interchanges the roles ofsource anddetector. This fact triggered the proposal of a host of (...)
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  4.  9
    How to Recover Causality in Special Relativity for Tachyons.Erasmo Recami - 1978 - Foundations of Physics 8 (5-6):329-340.
    In this paper we explain why and how tachyons do not imply any causality violation within relativistic theories. Particular emphasis is given to the role of the Stückelberg-Feynman reinterpretation principle, both in ordinary physics and in tachyon physics.
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  5.  17
    Antiparticles From Special Relativity with Ortho-Chronous and Antichronous Lorentz Transformations.Erasmo Recami & Waldyr A. Rodrigues - 1982 - Foundations of Physics 12 (7):709-718.
    Special Relativity can be based on the whole proper group of both ortho- and antichronous Lorentz transformations, and a clear physical meaning can be given also to antichronous (i.e., nonorthochronous) Lorentz transformations. From the active point of view, the latter requires existence, for any particle, of its antiparticle within a purely relativistic, classical context. From the passive point of view, they give rise to frames “dual” to the ordinary ones, whose properties—here briefly discussed—are linked with the fact that in relativity (...)
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  6.  47
    Deriving Spin Within a Discrete-Time Theory.Erasmo Recami & Giovanni Salesi - 2007 - Foundations of Physics 37 (2):277-294.
    We prove that the classical theory with a discrete time (chronon) is a particular case of a more general theory in which spinning particles are associated with generalized Lagrangians containing time-derivatives of any order (a theory that has been called “Non-Newtonian Mechanics”). As a consequence, we get, for instance, a classical kinematical derivation of Hamiltonian and spin vector for the mentioned chronon theory (e.g., in Caldirola et al.’s formulation). Namely, we show that the extension of classical mechanics obtained by the (...)
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  7.  21
    The Introduction of Superluminal Lorentz Transformations: A Revisitation. [REVIEW]G. D. Maccarrone & Erasmo Recami - 1984 - Foundations of Physics 14 (5):367-407.
    We revisit the introduction of the Superluminal Lorentz transformations which carry from “bradyonic” inertial frames to “tachyonic” inertial frames, i.e., which transform time-like objects into space-like objects, andvice versa. It has long been known that special relativity can be extended to Superluminal observers only by increasing the number of dimensions of the space-time or—which is in a sense equivalent—by releasing the reality condition (i.e., introducing also imaginary quantities). In the past we always adopted the latter procedure. Here we show the (...)
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  8.  12
    A Generalization of Dirac Nonlinear Electrodynamics, and Spinning Charged Particles.Waldyr A. Rodrigues, Jayme Vaz & Erasmo Recami - 1993 - Foundations of Physics 23 (3):469-485.
    In this paper—dedicated to Prof. Asim O. Barut—we generalize the Diracnon-linear electrodynamics by introducing two potentials(namely, the vector potential A and the pseudo-vector potential γ5B of the electromagnetic theorywith charges and magnetic monopoles) and by imposing the pseudoscalar part of the product ωω* to be zero, with ω≡A+γ5B. We show that the field equations of such a theory possess a soliton-like solution which can representa priori a “charged particle,” since it is endowed with a Coulomb field plus the field of (...)
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