scholarly journals A generalization of the Einstein–Maxwell equations

2021 ◽  
Vol 136 (2) ◽  
Author(s):  
Fredrick W. Cotton
Keyword(s):  
Maxwell Equations ◽  
Inertial Mass ◽  
The Other ◽  
Spherically Symmetric ◽  
Pressure Tensor ◽  
Wave Solutions ◽  
Isotropic Pressure ◽  
Pressure Term ◽  
Symmetric Connection ◽  
Constitutive Tensor

AbstractThe proposed modifications of the Einstein–Maxwell equations include: (1) the addition of a scalar term to the electromagnetic side of the equation rather than to the gravitational side, (2) the introduction of a four-dimensional, nonlinear electromagnetic constitutive tensor, (3) the addition of curvature terms arising from the non-metric components of a general symmetric connection and (4) the addition of a non-isotropic pressure tensor. The scalar term is defined by the condition that a spherically symmetric particle be force-free and mathematically well behaved everywhere. The constitutive tensor introduces two structure fields: One contributes to the mass and the other contributes to the angular momentum. The additional curvature terms couple both to particle solutions and to localized electromagnetic and gravitational wave solutions. The pressure term is needed for the most general spherically symmetric, static metric. It results in a distinction between the Schwarzschild mass and the inertial mass.

scholarly journals The Radiation-Dominated Universe in Nonstandard Cosmology

2020 ◽  
Vol 5 (4) ◽  
Author(s):  
Günter Scharf ◽  
Keyword(s):  
Evolution Equations ◽  
Big Bang ◽  
The Other ◽  
Spherically Symmetric ◽  
Velocity Perturbation ◽  
Model Universe ◽  
Cosmic Evolution ◽  
Big Crunch ◽  
The Big Bang ◽  
Irregular Singular Points

We continue the recent study of our model theory of low-density cosmology without dark matter. We assume a purely radiative spherically symmetric background and treat matter as anisotropic perturbations. Einstein’s equations for the background are solved numerically. We find two irregular singular points, one is the Big Bang and the other a Big Crunch. The radiation temperature continues to decrease for another 0.21 Hubble times and then starts to increase towards infinity. Then we derive the four evolution equations for the anisotropic perturbations. In the Regge- Wheeler gauge there are three metric perturbations and a radial velocity perturbation. The solution of these equations allow a detailed discussion of the cosmic evolution of the model universe under study.

Equivalence principle for charged bodies in a theory of gravitation

1981 ◽  
Vol 59 (11) ◽  
pp. 1730-1733 ◽  
Author(s):  
R. B. Mann ◽  
J. W. Moffat
Keyword(s):  
Equivalence Principle ◽  
Maxwell Equations ◽  
Test Body ◽  
Spherically Symmetric ◽  
Point Particles ◽  
Symmetric Field ◽  
Static Spherically Symmetric Metric ◽  
Theory Of Gravitation ◽  
Spherically Symmetric Metric

The motion of a test body made of electromagnetically interacting point particles, falling in the static spherically symmetric field of the Hermitian theory of gravitation is shown to not disagree with the Eötvös–Dicke–Braginsky experiments for the equivalence principle. The modified Maxwell equations are calculated in the isotropic static spherically symmetric metric, and the role of the equivalence principle in the new theory is discussed in detail.

scholarly journals Dynamical Instabilities in Spherical Stellar Systems

1985 ◽  
Vol 113 ◽  
pp. 297-299
Author(s):  
Joshua Barnes
Keyword(s):  
Mass Distribution ◽  
Spherical Symmetry ◽  
Mean Field ◽  
The Other ◽  
Stellar Systems ◽  
Spherically Symmetric ◽  
Quadrupole Mode ◽  
Radial Forces ◽  
The Mean ◽  
Dynamical Instabilities

Equlibrium spherical stellar systems exhibiting instabilities on a dynamical timescale were first studied by Henon (1973), using a spherically symmetric N-body code. We have re-examined Henon's models using an improved code which includes non-radial forces to quadrupole order. In addition to the radial instability reported by Henon, two new non-radial instabilities are also observed. In one, found in models with highly circular orbits, the mass distribution exhibits quadrupole-mode oscillations. In the other, seen in models with highly radial orbits, the system spontaneously breaks spherical symmetry and settles into a tri-axial ellipsoid. These instabilities, which are driven by fluctuations of the mean field, offer some analogies to the well-known dynamical instabilities of a cold disk of stars. While our models are rather artificial, they indicate that dynamical instabilities may be more common in spherical systems than had been thought.

scholarly journals An Interferometric Survey of Mira Variables and M Supergiants

1994 ◽  
Vol 158 ◽  
pp. 395-397
Author(s):  
P.G. Tuthill ◽  
C.A. Haniff ◽  
J.E. Baldwin
Keyword(s):  
Hot Spot ◽  
The Other ◽  
Spherically Symmetric ◽  
Preliminary Results ◽  
Mira Variables

We present preliminary results from an imaging survey of bright northern Mira variables and Supergiants. Diffraction-limited images of Mira exhibit the same elongation along PA 120° as observed in previous observations. Of the other Mira variables observed, R Cas is unambiguously detected as non-spherically symmetric. Our observations of α-Her are consistent with there being a ‘hot-spot’ on its surface, similar to those we have previously detected on Betelgeuse.

scholarly journals ADIABATIC EFFECTIVE ACTION FOR VORTICES IN NEUTRAL AND CHARGED SUPERFLUIDS

1996 ◽  
Vol 10 (15) ◽  
pp. 1875-1894 ◽  
Author(s):  
M. HATSUDA ◽  
M. SATO ◽  
S. YAHIKOZAWA ◽  
T. HATSUDA
Keyword(s):  
Effective Mass ◽  
Vortex Dynamics ◽  
Effective Action ◽  
Vortex Core ◽  
Berry Phase ◽  
Inertial Mass ◽  
The Other ◽  
Zero Temperature ◽  
Magnus Force ◽  
Phase Term

Adiabatic effective action for vortices in neutral and charged superfluids at zero temperature are calculated using the topological Landau-Ginzburg theory recently proposed by Hatsuda, Yahikozawa, Ao and Thouless, and vortex dynamics are examined. The Berry phase term arising in the effective action naturally yields the Magnus force in both neutral and charged superfluids. It is shown that in neutral superfluid there is only one degree of freedom, namely the center of vorticities, and the vortex energy is proportional to the sum of all vorticities so that it is finite only for the vanishing total vorticity of the system. On the other hand the effective mass and the vortex energy for a vortex in charged superfluids are defined individually as expected. The effects of the vortex core on these quantities are also estimated. The possible depinning scenario which is governed by the Magnus force and the inertial mass is also discussed.

Exact solutions of the Einstein–Maxwell equations with linear equation of state

2012 ◽  
Vol 90 (12) ◽  
pp. 1179-1183 ◽  
Author(s):  
Tooba Feroze
Keyword(s):  
Equation Of State ◽  
Linear Equation ◽  
Maxwell Equations ◽  
Momentum Conservation ◽  
Conservation Equation ◽  
Fluid Distribution ◽  
Spherically Symmetric ◽  
Field Equations ◽  
General Linear Equation ◽  
Energy Momentum Conservation

Two new classes of solutions of the Einstein–Maxwell field equations are obtained by substituting a general linear equation of state into the energy–momentum conservation equation. We have considered static, anisotropic, and spherically symmetric charged perfect fluid distribution of matter with a particular form of gravitational potential. Expressions for the mass–radius ratio, the surface, and the central red shift horizons are given for these solutions.

scholarly journals EXPANSIONFREE FLUID EVOLUTION AND SKRIPKIN MODEL IN f(R) THEORY

2011 ◽  
Vol 20 (11) ◽  
pp. 2239-2252 ◽  
Author(s):  
M. SHARIF ◽  
H. RIZWANA KAUSAR
Keyword(s):  
General Relativity ◽  
The Self ◽  
Spherically Symmetric ◽  
Junction Conditions ◽  
Dynamical Equations ◽  
Constant Energy ◽  
Isotropic Pressure ◽  
Symmetric Star ◽  
Constant Energy Density ◽  
General Influence

We consider the modified f(R) theory of gravity whose higher-order curvature terms are interpreted as a gravitational fluid or dark source. The gravitational collapse of a spherically symmetric star, made up of locally anisotropic viscous fluid, is studied under the general influence of the curvature fluid. Dynamical equations and junction conditions are modified in the context of f(R) dark energy and by taking into account the expansionfree evolution of the self-gravitating fluid. As a particular example, the Skripkin model is investigated which corresponds to isotropic pressure with constant energy density. The results are compared with corresponding results in General Relativity.

scholarly journals DISPERSIVE SOLITARY WAVE SOLUTIONS OF COUPLING BOITI-LEON-PEMPINELLI SYSTEM USING TWO DIFFERENT METHODS

2021 ◽  
Vol 21 (1) ◽  
pp. 91-104
Author(s):  
MAHA S.M. SHEHATA ◽  
HADI REZAZADEH ◽  
EMAD H.M. ZAHRAN ◽  
MOSTAFA ESLAMI ◽  
AHMET BEKIR
Keyword(s):  
Solitary Wave ◽  
Solitary Waves ◽  
Traveling Wave ◽  
Traveling Wave Solutions ◽  
The Other ◽  
Solitary Wave Solutions ◽  
Exact Traveling Wave Solutions ◽  
Wave Solutions ◽  
Special Value ◽  
Ode Method

In this paper, new exact traveling wave solutions for the coupling Boiti-Leon-Pempinelli system are obtained by using two important different methods. The first is the modified extended tanh function methods which depend on the balance rule and the second is the Ricatti-Bernoulli Sub-ODE method which doesn’t depend on the balance rule. The solitary waves solutions can be derived from the exact wave solutions by give the parameters a special value. The consistent and inconsistent of the obtained solutions are studied not only between these two methods but also with that relisted by the other methods.

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