Extension of General Relativity

Nonlocal general relativity (GR) requires an extension of the mathematical framework of GR. Nonlocal GR is a tetrad theory such that the orthonormal tetrad frame field of a preferred set of observers carries the sixteen gravitational degrees of freedom. The spacetime metric is then defined via the orthonormality condition. The preferred frame field is used to define a new linear Weitzenböck connection in spacetime. The non-symmetric Weitzenböck connection is metric compatible, curvature-free and renders the preferred (fundamental) frame field parallel. This circumstance leads to teleparallelism. The fundamental parallel frame field defined by the Weitzenböck connection is the natural generalization of the parallel frame fields of the static inertial observers in a global inertial frame in Minkowski spacetime. The Riemannian curvature of the Levi-Civita connection and the torsion of the Weitzenböck connection are complementary aspects of the gravitational field in extended GR.

Møller's Energy in the Kantowski-Sachs Space-Time

We have shown that the fourth component of Einstein's complex for the Kantowski-Sachs space-time is not identically zero. We have calculated the total energy of this space-time by using the energy-momentum definitions of Møller in the theory of general relativity and the tetrad theory of gravity.

ENERGY AND ANGULAR MOMENTUM OF GENERAL FOUR-DIMENSIONAL STATIONARY AXI-SYMMETRIC SPACE–TIME IN TELEPARALLEL GEOMETRY

We derive an exact general axi-symmetric solution of the coupled gravitational and electromagnetic fields in the tetrad theory of gravitation. The solution is characterized by four parameters: M (mass), Q (charge), a (rotation) and L (NUT). We then calculate the total exterior energy using the energy–momentum complex given by Møller in the framework of Weitzenböck geometry. We show that the energy contained in a sphere is shared by its interior as well as exterior. We also calculate the components of the spatial momentum to evaluate the angular momentum distribution. We show that the only nonvanishing components of the angular momentum is in the Z direction.

REISSNER–NORDSTRÖM SPACE–TIME IN THE TETRAD THEORY OF GRAVITATION

We give two classes of spherically symmetric exact solutions of the coupled gravitational and electromagnetic fields with charged source in the tetrad theory of gravitation. The first solution depends on an arbitrary function H(R,t). The second solution depends on a constant parameter η. These solutions reproduce the same metric, i.e. the Reissner–Nordström metric. If the arbitrary function which characterizes the first solution and the arbitrary constant of the second solution are set to be zero, then the two exact solutions will coincide with each other. We then calculate the energy content associated with these analytic solutions using the superpotential method. In particular, we examine whether these solutions meet the condition, which Møller required for a consistent energy–momentum complex, namely, we check whether the total four-momentum of an isolated system behaves as a four-vector under Lorentz transformations. It is then found that the arbitrary function should decrease faster than [Formula: see text] for R → ∞. It is also shown that the second exact solution meets the Møller's condition.

REISSNER–NORDSTRÖM SOLUTIONS AND ENERGY IN TELEPARALLEL THEORY

We give three different spherically symmetric spacetimes for the coupled gravitational and electromagnetic fields with charged source in the tetrad theory of gravitation. One of these contains an arbitrary function and generates the others. These spacetimes give the Reissner–Nordström metric black hole. We then calculated the energy associated with these spacetimes using the superpotential method. We find that unless the time-space components of the tetrad field go to zero faster than [Formula: see text] at infinity, one gets different results for the energy.

CHARGED AXIALLY SYMMETRIC SOLUTION, ENERGY AND ANGULAR MOMENTUM IN TETRAD THEORY OF GRAVITATION

Charged axially symmetric solution of the coupled gravitational and electromagnetic fields in the tetrad theory of gravitation is derived. The metric associated with this solution is an axially symmetric metric which is characterized by three parameters "the gravitational mass M, the charge parameter Q and the rotation parameter a." The parallel vector fields and the electromagnetic vector potential are axially symmetric. We calculate the total exterior energy. The energy–momentum complex given by Møller in the framework of the Weitzenböck geometry "characterized by vanishing the curvature tensor constructed from the connection of this geometry" has been used. This energy–momentum complex is considered as a better definition for calculation of energy and momentum than those of general relativity theory. The energy contained in a sphere is found to be consistent with pervious results which is shared by its interior and exterior. Switching off the charge parameter, one finds that no energy is shared by the exterior of the charged axially symmetric solution. The components of the momentum density are also calculated and used to evaluate the angular momentum distribution. We found no angular momentum contributes to the exterior of the charged axially symmetric solution if zero charge parameter is used.