Scalar Theory Of Gravitation Research Articles

Spectral Energy Density in an Axisymmetric Galaxy as Predicted by an Analytical Model for the Maxwell Field

An analytical model for the Maxwell radiation field in an axisymmetric galaxy, proposed previously, is first checked for its predictions of the spatial variation of the spectral energy distributions (SEDs) in our Galaxy. First, the model is summarized. It is now shown how to compute the SED with this model. Then the model is adjusted by asking that the SED predicted at our local position in the Galaxy coincides with the available observations. Finally, the first predictions of the model for the spatial variation of the SED in the Galaxy are compared with those of a radiation transfer model. We find that the two predictions do not differ too much. This indicates that, in a future work, it should be possible with the present model to check if the “interaction energy” predicted by an alternative, scalar theory of gravitation, contributes to the dark matter.

Interaction Energy of a Charged Medium and its EM Field in a Curved Spacetime

In the electrodynamics of special relativity (SR) or general relativity (GR), the energy tensors of the charged medium and its EM field add to give the total energy tensor that obeys the dynamical equation without external force. In the investigated scalar theory of gravitation (SET), this assumption leads to charge non-conservation, hence an additional, interaction energy tensor T inter has to be postulated. The present work aims at constraining this tensor. First we study the independent equations of electrodynamics and their number, beginning with SR and GR. As in SR and GR, the system of electrodynamics of SET is closed in the absence of T inter. Hence, with T inter , at least one additional equation must be provided. This is done by assuming that T inter is Lorentz-invariant in the situation of SR. We derive equations allowing one in principle to compute T inter in a given gravitational plus EM field. T inter may contribute to the dark matter.

Tilted Bianchi type-I wet dark fluid model in Saez and Ballester theory

Tilted Bianchi-I wet dark fluid cosmological model is investigated in Saez and Ballester scalar theory of gravitation. Background cosmologies are obtained for a constant deceleration parameter. We consider a linear relationship between the shear scalar and the expansion scalar. We have discussed some physical and geometrical properties of the models. In our models, equation of state of the dark energy is observed to behave like a cosmological constant at late times.

Continuum dynamics and the electromagnetic field in the scalar ether theory of gravitation

AbstractAn alternative, scalar theory of gravitation has been proposed, based on a mechanism/interpretation of gravity as being a pressure force: Archimedes’ thrust. In it, the gravitational field affects the physical standards of space and time, but motion is governed by an extension of the relativistic form of Newton’s second law. This implies Einstein’s geodesic motion for free particles only in a constant gravitational field. In this work, equations governing the dynamics of a continuous medium subjected to gravitational and non-gravitational forces are derived. Then, the case where the non-gravitational force is the Lorentz force is investigated. The gravitational modification of Maxwell’s equations is obtained under the requirement that a charged continuous medium, subjected to the Lorentz force, obeys the equation derived for continuum dynamics under external forces. These Maxwell equations are shown to be consistent with the dynamics of a “free” photon, and thus with the geometrical optics of this theory. However, these equations do not imply local charge conservation, except for a constant gravitational field.

Post-Newtonian Approximation of the Vlasov–Nordström System

ABSTRACT We study the Nordström–Vlasov system, which describes the dynamics of a self-gravitating ensemble of collisionless particles in the framework of the Nordström scalar theory of gravitation. If the speed of light c is considered as a parameter, it is known that in the Newtonian limit c → ∞ the Vlasov–Poisson system is obtained. In this paper we determine a higher approximation and establish a pointwise error estimate of order 𝒪(c −4). Such an approximation is usually called a 1.5 post-Newtonian approximation.

Global Existence of Classical Solutions of the Nordström–Vlasov System in Two Space Dimensions

ABSTRACT The dynamics of a self-gravitating ensemble of collisionless particles is modeled by the Nordström–Vlasov system in the framework of the Nordström scalar theory of gravitation. For this system in two space dimensions, integral representations of the first-order derivatives of the field are derived. Using these representations we show global existence of smooth solutions for large data.

On Classical Solutions of the Nordström-Vlasov System

The Nordström-Vlasov system describes the dynamics of a self-gravitating ensemble of collisionless particles in the framework of the Nordström scalar theory of gravitation. We prove existence and uniqueness of classical solutions of the Cauchy problem in three dimensions and establish a condition which guarantees that the solution is global in time. Moreover, we show that if one changes the sign of the source term in the field equation, which heuristically corresponds to the case of a repulsive gravitational force, then solutions blow up in finite time for a large class of initial data. Finally, we prove global existence of classical solutions for the one dimensional version of the system with the correct sign in the field equation.

Accelerated Expansion as Predicted by an Ether Theory of Gravitation

Cosmology is investigated within a new, scalar theory of gravitation, which is a preferred-frame bimetric theory with flat background metric. Before coming to cosmology, the motivation for an ether theory is exposed at length; the investigated concept of ether is presented: it is a compressible fluid, and gravity is seen as Archimedes' thrust due to the pressure gradient in that fluid. The construction of the theory is explained and the current status of the experimental confrontation is analysed, both in some detail. An analytical cosmological solution is obtained for a general form of the energy-momentum tensor. According to that theory, expansion is necessarily accelerated, both by vacuum and even by matter. In one case, the theory predicts expansion, the density increasing without limit as time goes back to infinity. High density is thus obtained in the past, without a big-bang singularity. In the other case, the Universe follows a sequence of (non-identical) contraction-expansion cycles, each with finite maximum energy density; the current expansion phase will end by infinite dilution in some six billions of years. The density ratio of the present cycle (ratio of the maximum to current densities) is not determined by the current density and the current Hubble constant H0, unless a special assumption is made. Since cosmological redshifts approaching z = 4 are observed, the density ratio should be at least 100. From this and the estimate of H0, the time spent since the maximum density is constrained to be larger than several hundreds of billions of years. Yet if a high density ratio, compatible with the standard explanation for the light elements and the 2.7 K radiation, is assumed, then the age of the Universe is much larger still.

Scalar gravitation and cosmology

The objective of this paper is to discuss some implications of a scalar theory of gravitation developed in a previous paper. At the beginning we shall show that, on the basis of a scalar theory of gravitation, it is possible to predict a gravitational light drag. The remainder of this paper is devoted to cosmology. We shall prove that Hubble's red-shift, the existence of an age and an «effective radius» of the Universe can be deduced from a model of universe that is Euclidean, infinite and nonexpanding. Finally, we discuss briefly Olbers' paradox and the thermal evolution of the Universe.

Attempt to construct a general covariant theory of a scalar gravitational field

An attempt is made in this paper to construct a scalar theory of gravitation which is based on the main postulates of the general theory of relativity (GTR), i.e., on the principle of the equivalence of inertial and gravitational mass and on the principle of general covariance of the theory.

A coupled theory of electromagnetism and gravitation

A coupling electromagnetism with a previously developed scalar theory of gravitation is presented. The principle features of this coupling are: (1) a slight alteration to the Maxwell equations, (2) the motion of a charged particle satisfies an equation with the Lorentz force-appearing on the right side in place of zero, and (3) the energy density of the electromagnetic field appears in the gravitational field equation in a manner similar to the mass term in the Klein-Gordonequation. The field of a static, spherically symmetric charged particle is computed. The electromagnetic field gives rise to l/r2 terms in the gravitational potential.

A scalar field theory of gravitation

A scalar theory of gravitation is developed from a variational principle. The speed of light is taken to be a function of the potential of the gravitational field. The predictions of the light deflection and the advancement of the perihelion agree with those made by Einstein's theory. The gravitational (active) mass differs from the inertial (passive) mass and both are dependent on the gravitational potential.

Gravitational Field Equations

An earlier, scalar theory of gravitation is assumed to be valid for a class of static gravitational fields. The theory is written in tensor form, and generalized to the case of an arbitrary gravitational field. The interaction between the field and its sources is discussed, and the linearized form of the field equations is derived. Some possible alternative field equations are considered which are compatible with the linearized Einstein equations.

Planetary orbits for a moving Sun

The scalar theory of gravitation is known to be in agreement with observed planetary motions if the Sun is assumed to be stationary with respect to the preferred coordinate systems of the theory. We now assume that the Sun is moving, and we find that, unless its speed is improbably small, there are observable effects on the planetary orbits. The difficulty can be overcome if one assumes that the Newtonian charts are determined by the distribution of matter.

Relativistic magnetohydrodynamics of a gravitating fluid

The system of hydrodynamical equations governing the behaviour of an ideal, relativistic, charged, gravitating fluid are derived from a variational principle. Gravitational effects are first included by making use of Einstein’s theory of general relativity. An alternative formalism, using a scalar theory of gravitation, is then discussed.

Scalar Gravitational Theories with Variable Velocity of Light

Scalar Gravitational Theories with Variable Velocity of Light

A scalar theory of gravitation

A scalar gravitational theory is introduced which gives the correct rotation of the perihelion.

Scalar Gravitation

Nordström's scalar theory of gravitation is discussed from a modern point of view, and compared with some aspects of general relativity. We discuss the equations of motion for test masses, the field equations in the presence of matter, and the extent to which the principle of equivalence, Mach's principle, and the expansion of the universe are contained in this model. The theory implies what amounts to a Riemannian metric, and features a positive energy density for the gravitational field.

AN APPROACH TO A THEORY OF GRAVITATION

The form of the space–time metric in a scalar theory of gravitation follows from the assumption that the potential is arbitrary to the extent of an additive constant. No field equations are needed. Expressions are found for the gravitational red shift, the perihelion motion of a planet, and the bending of light by the sun. From the observed values of these quantities one can determine the metric and the potential due to a gravitating mass.