Equations of a gravitational field in the quadratic theory of gravitation

1977 ◽  
Vol 20 (3) ◽  
pp. 411-412
Author(s):  
B. N. Frolov
Open Physics ◽  
2016 ◽  
Vol 14 (1) ◽  
pp. 395-409 ◽  
Author(s):  
Mayeul Arminjon

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.


1976 ◽  
Vol 31 (10) ◽  
pp. 1155-1159 ◽  
Author(s):  
F. Vollendorf

Abstract This article is based upon the idea to solve the problem of combining the electromagnetic and the gravitational field by starting from Maxwell's theory. It is shown that the theory of the Maxwell field can be generalized in such a way that Einstein's theory of gravitation becomes a special case of it. Finally we find field equations which refer only to geometric quantities.


Author(s):  
Hanoch Gutfreund ◽  
Jürgen Renn

This section presents annotations of the manuscript of Albert Einstein's canonical 1916 paper on the general theory of relativity. It begins with a discussion of the foundation of the general theory of relativity, taking into account Einstein's fundamental considerations on the postulate of relativity, and more specifically why he went beyond the special theory of relativity. It then considers the spacetime continuum, explaining the role of coordinates in the new theory of gravitation. It also describes tensors of the second and higher ranks, multiplication of tensors, the equation of the geodetic line, the formation of tensors by differentiation, equations of motion of a material point in the gravitational field, the general form of the field equations of gravitation, and the laws of conservation in the general case. Finally, the behavior of rods and clocks in the static gravitational field is examined.


2021 ◽  
Vol 64 (1) ◽  
pp. 10-15
Author(s):  
A.A. Baiderin ◽  
◽  
I.P. Denisova ◽  
V.S. Rostovsky ◽  
◽  
...  

The theory of gravitation with a massive graviton, which was proposed by Visser, is considered. The exact solution of this theory is found when the source of the gravitational field is plane scalar wave. The Hamilton-Jacobi method obtained the laws of motion of massive and massless particles in this gravitational field.


Galaxies ◽  
2018 ◽  
Vol 6 (2) ◽  
pp. 41 ◽  
Author(s):  
Norman Israel ◽  
John Moffat

A major hurdle for modified gravity theories is to explain the dynamics of galaxy clusters. A case is made for a generalized gravitational theory called Scalar-Tensor-Vector-Gravity (STVG) or MOG (Modified Gravity) to explain merging cluster dynamics. The paper presents the results of a re-analysis of the Bullet Cluster, as well as an analysis of the Train Wreck Cluster in the weak gravitational field limit without dark matter. The King- β model is used to fit the X-ray data of both clusters, and the κ -maps are computed using the parameters of this fit. The amount of galaxies in the clusters is estimated by subtracting the predicted κ -map from the κ -map data. The estimate for the Bullet Cluster is that 14.1 % of the cluster is composed of galaxies. For the Train Wreck Cluster, if the Jee et al. data are used, 25.7 % of the cluster is composed of galaxies. The baryon matter in the galaxies and the enhanced strength of gravitation in MOG shift the lensing peaks, making them offset from the gas. The work demonstrates that this generalized gravitational theory can explain merging cluster dynamics without dark matter.


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