On the most general linear theory of gravitation

The most general field theory of gravitation is analyzed both group theoretically as well as physically. The field equations are solved by means of an algebraic method and it is found that any field theory of gravitation contains only one essential parameter which is correlated to the spin 0 content of the field. Further it turns out that any theory of gravitation must contain a nonvanishing spin 0 part, but general relativity is distinguished by the fact that its spin 0 component cannot be radiated.     

Phase coupling gravitation: Symmetries and gauge fields

We consider possible generalizations of phase coupling gravitation, a relativistic theory introduced to account for the astrophysical missing mass problem in the framework of departures from newtonian gravitation. We show that pure phase coupled gravitation cannot be gauged. However, the theory can be extended by modifying the interactions. It is then endowed with a continuous global symmetry which can be gauged.     

On Gravitational Energy in Newtonian Theories

There are well-known problems associated with the idea of (local) gravitational energy in general relativity. We offer a new perspective on those problems by comparison with Newtonian gravitation, and particularly geometrized Newtonian gravitation (i.e., Newton–Cartan theory). We show that there is a natural candidate for the energy density of a Newtonian gravitational field. But we observe that this quantity is gauge dependent, and that it cannot be defined in the geometrized (gauge-free) theory without introducing further structure. We then address a potential response by showing that there is an analogue to the Weyl tensor in geometrized Newtonian gravitation.     

Are There Thermodynamical Degrees of Freedom of Gravitation?

In discussing fundamentals of general-relativistic irreversible continuum thermodynamics, this theory is shown to be characterized by the feature that no thermodynamical degrees of freedom are ascribed to gravitation. However, accepting that black hole thermodynamics seems to oppose this harmlessness of gravitation one is called on to consider other approaches. Therefore, in brief some gravitational and thermodynamical alternatives are reviewed.     

Minimal gravitational coupling in the Newtonian theory and the covariant Schrödinger equation

The role of the Bargmann group (11-dimensional extended Galilei group) in nonrelativistic gravitation theory is investigated. The generalized Newtonian gravitation theory (Newton-Cartan theory) achieves the status of a gauge theory about as much as general relativity and couples minimally to a complex scalar field leading to a four-dimensionally covariant Schrödinger equation. Matter current and stress-energy tensor follow correctly from the Lagrangian. This theory on curved Newtonian space-time is also shown to be a limit of the Einstein-Klein-Gordon theory.Partially supported by the Natural Sciences and Engineering Research Council of Canada, Grant No. A8059.     

Generalized theory of gravitation

The mathematical formulation of the nonsymmetric gravitation theory (NGT) as a geometrical structure is developed in a higher-dimensional space. The reduction of the geometrical scheme to a dynamical theory of gravitation in four-dimensional space-time is investigated and the basic physical laws of the theory are reviewed in detail.     

On the Definition of Gauge Transformations in Gauge Theory

The different types of gauge transformations in gauge theory are discerned and defined in fiber bundle terms. The gauge gravitation case is analysed in order to examine various versions of the gauge gravitation theory.     

Weak circulation theorems as a way of distinguishing between generalized gravitation theories

We proved in a previous paper that a generalized circulation theorem characterizes Einstein's theory of gravitation as a special case of a more general theory of gravitation, which is also based on the principle of equivalence. Here we pose the question of whether it is possible to weaken this circulation theorem in such ways that it would imply more general theories than Einstein's. This problem is solved. Principally, there are two possibilities. One of them is essentially Weyl's theory.     

A spin-3/2 theory of gravitation

Stimulated by ideas occuring in supergravity, we develop a gauge theory of gravity based on a spin-3/2 Majorana field. Our theory has no metric or vierbein as an elementary field. Classically the theory is in complete agreement with Einstein's metric formulation, but quantum mechanically it differs from ordinary formulations, including supergravity, on the fundamental nature of gravitation. In our approach gravitation arises from a collective effect due to spin-3/2 gravitinos.This essay was awarded the fifth prize for 1978 by the Gravity Research Foundation. (Ed.) Research supported in part by the Department of Energy under contract number EY-76-C-02-3075-190.Alfred P. Sloan Foundation Fellow.     

Precession of Orbiting Gyroscope in Higher-Order Gravitational Field Caused by Rotating Body

The metric for a spinning massive object with any shape and composition is found by the use of linearized higher-order theory of gravitation. The geodesic and the Lense–Thirring precessions for an orbiting gyroscope in a general weak higher-order gravitational field are considered. The influences of the additional Yukawa forces included in the linearized higher-order gravitation on the precessions are investigated.     

Some Interesting Features for External Region of Spherical Symmetric Mass in New Theory of Gravitation VGM

This paper briefly discusses some interesting features for the external region of the spherical symmetric mass in the new theory of gravitation VGM, i.e. the theory of gravitation by considering the vector graviton field and the metric field, such as pseudo-singularity, curvature tensor, static limit, event horizon, and the radial motion of a particle. All these features are different from the corresponding features obtained from general relativity.     

Strong gravitation waves in terms of Maurer-Cartan forms

Strong gravitation plane waves are represented in terms of the Maurer-Cartan spin connection coefficients in cosmological background. It was shown that the diffeo-invariance of spin connection coefficients leaves only one degree of freedom of the strong gravitation plane waves in contrast to the metric approach, where gravitation waves have two degrees of freedom like photons in QED. The Hilbert action of gravitation waves in terms of spin connection coefficients takes the form of a bilinear field theory.     

Physical foundations of the new theory of gravitation

It is shown that in generalizing simultaneously the special theory of relativity and the Newtonian theory of gravitation into a curved-space theory of gravity one needs to satisfy second-order correspondence conditions as well as the usual first-order ones. It is further shown that the imposition of these second-order conditions leads to a locally Lorentz invariant spin-2 field theory of gravity which is in agreement with all the known facts concerning gravitation. The second-order correspondence requirements endow the curved-space theory of gravitation with experimentally and theoretically novel features which will be discussed in some detail.     

Some Interesting Features for External Region of Spherical Symmetric Mass in New Theory of Gravitation VGM

This paper briefly discusses some interesting features for the external region of the spherical symmetric mass in the new theory of gravitation VGM, Le. The theory of gravitation by considering the vector graviton field and the metric field, such as pseudo-singularity, curvature tensor, static limit, event horizon, and the radial motion of a particle. All these features are different from the corresponding features obtained from general relativity.     

On Treder-Type Tetrad Theories of Gravitation I. Equivalence Principle and Invariance Properties

The Principle of relativity and the equivalence principle are the most important foundation of any theory of gravitation. We can formulate these principles by the help of the LORENTZ and the EINSTEIN groups. If we start with an action functional, the demand of invariance of this action with respect to these groups makes possible to get detailed conclusions about the general structure of theories of gravitation. EINSTEIN'S idea, to interpret gravitation as deformation of the local inertial systems of the special theory of relativity, leads to bi-tetrad theories, which we call TREDER-type tetrad theories. In this theories a sufficient number of gauge parameters is introduced in order to ensure the invariance of the action functional without limitations for the field variables.     

Electrodynamical origins of Einstein's theory of general relativity

The failure of the Newtonian theory of gravitation to satisfactorily account for the motion of Mercury's perihelion cannot be held to have justified the development of general relativity. This paper shows how the origins of general relativity were firmly embedded in contemporary attempts to introduce the new mechanics of special relativity into gravitational theory. These new theories of gravitation took as their basis the electrodynamical equations as formulated by Minkowski and attempted to represent the gravitational potential first by a vector and then by a scalar (in the four-dimensional sense). That Einstein chose the symmetric fundamental tensorg _ij as his gravitational potential is seen to have been both a natural and necessary development. With this viewpoint the full theory of general relativity can be seen to be remarkably similar to those theories of gravitation that preceded it. The paper also contains a previously unpublished letter written by Einstein to H. A. Lorentz.     

Preferred frames and oscillating universes

A metric theory of gravitation is presented. It is based on the existence of a preferred ‘cosmic’ time. It agrees with all present experimental facts regarding gravitation and leads to singularity-free oscillating universes.     

Gravitation and source theory

Schwinger's source theory is applied to the problem of gravitation and its quantization. It is shown that within the framework of a flat-space the source theory implementation leads to a violation of probability. To avoid the difficulty one must introduce a curved space-time hence the source concept may be said to necessitate the transition to a curved-space theory of gravitation. It is further shown that the curved-space theory of gravitation implied by the source theory is not equivalent to the conventional Einstein theory. The source concept leads to a different theory where the gravitational field has a stress-energy tensor t_μ^ν, which contributes to geometric curvatures.     

The interaction of three fields in ECE theory: The inverse Faraday effect

The simultaneous interaction of three fundamental fields is illustrated in Einstein Cartan Evans (ECE) theory with reference to the effect of gravitation on the inverse Faraday effect. The three-field interaction in this case is that of the fermionic, electromagnetic and gravitational fields. The interaction of the first two is developed in a well-defined semi-classical approximation of the ECE wave equation and the effect of gravitation incorporated through the index reduced canonical energy momentum density T. The exercise is repeated using the ECE wave equations and a general rule developed for the effect of gravitation on the fermionic, electromagnetic weak and strong fields.