The Experts below are selected from a list of 276 Experts worldwide ranked by ideXlab platform
Piotr Bizoń - One of the best experts on this subject based on the ideXlab platform.
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Stability of Einstein Yang-Mills black holes☆
Physics Letters B, 1991Co-Authors: Piotr BizońAbstract:Abstract We examine the problem of stability of Einstein Yang-Mills black holes, studied recently by Straumann and Zhou in the framework of linearized perturbation technique. It is pointed out that the existence of the exponentially growing radial mode, found by Straumann and Zhou, does not necessarily signal behaviour at the horizon. In particular, we show that the lowest-energy coloured black hole is linearly stable against radial perturbations. We show also that the SU(2) Reissner-Nordstrom solution with mass M and magnetic charge 1 g is dynamically stable if the Dimensionless Constant G 1 2 gM is bigger than some critical value.
Nirod K. Das - One of the best experts on this subject based on the ideXlab platform.
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A New Unified Electro-Gravity Theory for the Electron, and the Fundamental Origin of the Fine Structure Constant and the Casimir Effect
2020Co-Authors: Nirod K. DasAbstract:A rigorous model for the electron is presented by generalizing the Coulomb’s Law or Gauss’s Law of electrostatics, using a unified theory of electricity and gravity. The permittivity of the free-space is allowed to be variable, dependent on the energy density associated with the electric field at a given location, employing generalized concepts of gravity and mass/energy density. The electric field becomes a non-linear function of the source charge, where the concept of the energy density needs to be properly defined. Stable solutions are derived for a spherically symmetric, surface-charge distribution of an elementary charge. This is implemented by assuming that the gravitational field and its equivalent permittivity function is proportional to the energy density, as a simple first-order approximation, with the Constant of proportionality, referred to as the Unified Electro-Gravity (UEG) Constant. The stable solution with the lowest mass/energy is assumed to represent a “static” electron without any spin. Further, assuming that the mass/energy of a static electron is half of the total mass/energy of an electron including its spin contribution, the required UEG Constant is estimated. More fundamentally, the lowest stable mass of a static elementary charged particle, its associated classical radius, and the UEG Constant are related to each other by a Dimensionless Constant, independent of any specific value of the charge or mass of the particle. This Dimensionless Constant is numerologically found to be closely related to the fine structure Constant. This possible origin of the fine structure Constant is further strengthened by applying the proposed theory to successfully model the Casimir effect, from which approximately the same above relationship between the UEG Constant, electron’s mass and classical radius, and the fine structure Constant, emerges.
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A New Unified Electro-Gravity Theory for the Electron
2019Co-Authors: Nirod K. DasAbstract:A rigorous model for the electron is presented by generalizing the Coulomb's Law or Gauss's Law of electrostatics, using a unified theory of electricity and gravity. The permittivity of the free-space is allowed to be variable, dependent on the energy density associated with the electric field at a given location, employing generalized concepts of gravity and mass/energy density. The electric field becomes a non-linear function of the source charge, where concept of the energy density needs to be properly defined. Stable solutions are derived for a spherically symmetric, surface-charge distribution of an elementary charge. This is implemented by assuming that the gravitational field and its equivalent permittivity function is proportional to the energy density, as a simple first-order approximation, with the Constant of proportionality referred to as the Unifield Electro-Gravity (UEG) Constant. The stable solution with the lowest mass/energy is assumed to represent a ``static'' electron without any spin. Further, assuming that the mass/energy of a static electron is half of the total mass/energy of an electron including its spin contribution, the required UEG Constant is estimated. More fundamentally, the lowest stable mass of a static elementary charged particle, its associated classical radius, and the UEG Constant are related to each other by a Dimensionless Constant, independent of any specific value of the charge or mass of the particle. This Dimensionless Constant is numerologically found to be closely related to the the fine structure Constant. This possible origin of the fine structure Constant is further strengthened by applying the proposed theory to successfully model the Casimir effect, from which approximately the same above relationship between the UEG Constant, electron's mass and classical radius, and the fine structure Constant, emerges.
R.p. Mathur - One of the best experts on this subject based on the ideXlab platform.
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Fracture toughness studies in sintered SmCo5 magnets
Journal of Magnetism and Magnetic Materials, 2015Co-Authors: R.k. Singh, S.v. Kamat, R.p. MathurAbstract:Abstract The fracture toughness of sintered SmCo5 magnets were systematically evaluated using both three point bend tests as well as Vickers indentation tests. These results were used for establishing the empirical Dimensionless Constant (χ) for evaluating indentation fracture toughness in SmCo5 magnets. The anisotropic behaviour of mechanical properties such as hardness, elastic modulus and fracture toughness was also investigated.
James Rich - One of the best experts on this subject based on the ideXlab platform.
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Experimental Consequences of Time Variations of the Fundamental Constants
American Journal of Physics, 2003Co-Authors: James RichAbstract:We discuss the experimental consequences of hypothetical time variations of the fundamental Constants. We emphasize that from a purely phenomenological point of view, only Dimensionless fundamental Constants have significance. Two classes of experiments are identified that give results that are essentially independent of the values of all Constants. Finally, we show that experiments that are generally interpreted in terms of time variations of the dimensioned gravitional Constant $G$ are better interpreted as giving limits on the variation of the Dimensionless Constant $\alpha_G=Gm_p^2/\hbar c$.
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Experimental consequences of time variations of the fundamental Constants
American Journal of Physics, 2003Co-Authors: James RichAbstract:We discuss the experimental consequences of hypothetical time variations of the fundamental Constants. We show that any observed time variations can be interpreted as being due to changes in the Dimensionless fundamental Constants, once the effects of the Constants on the structure of the experiment are taken into account. Young’s experiment for a slow charged particle and a version of the twin paradox are discussed to show how their results are independent of physical Constants. We also show that experiments that are generally interpreted in terms of time variations of the gravitational Constant G are better interpreted as giving limits on the variation of the Dimensionless Constant αG=Gmp2/ℏc, where mp is the mass of the proton.
Yukio Kaneda - One of the best experts on this subject based on the ideXlab platform.
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Energy spectrum in the enstrophy transfer range of two-dimensional forced turbulence
Physics of Fluids, 2001Co-Authors: Takashi Ishihara, Yukio KanedaAbstract:Numerical simulations of two-dimensional forced turbulence suggest that the enstrophy transfer range energy spectrum E(k) a little steeper than k−3 is robust in the sense that it may be realized in a wave number range under different run conditions. It is shown that such energy spectra fit well E(k)=CKη2/3k−3[ln(k/k1)]−1/3, where CK is a Dimensionless Constant, η the enstrophy transfer rate per unit mass and k1 a wave number at the bottom of the range. The simulations give CK≈1.9 in fairly good agreement with the existing theoretical estimates.