[en] The increased importance and the fundamental significance of accurately measuring the gravitational constant, G, are discussed along with recent or proposed experimental measurements of G. The method of using mutually gravitating bodies in the clock mode in a drag-free satellite is described. A satellite experiment consisting of the flat-plate spherical mass oscillator proposed combines the mathematical and experimental conveniences most simply. It is estimated that accuracies of 1 part in 1,000,000 are easily obtainable by careful fabrication of parts. The use of cryogenic techniques, thin films, and superconductors allows increased accuracies of two or three orders of magnitude or better. These measurements can be increased to the level of 1 part in 10'', at which time-variations, and other variations, in G can be observed

[en] The coordinate independence of gravitational radiation and the parameterized post-Newtonian approximation from which it is extended are described. The general consistency of the field equations with Bianchi identities, gauge conditions, and the Newtonian limit of the perfect fluid equations of hydrodynamics are studied. A technique of modification is indicated for application to vector-metric or double metric theories, as well as to scalar--tensor theories

[en] The concept of a primordial black hole fluid is introduced and its consequence for supercluster-sized (i.e., large scale) voids and the missing mass question are discussed

[en] The concept of a primordial blackhole fluid with intrinsic spin density is examined along with its consequence for supercluster-sized, i.e., large scale voids, and the missing mass question

[en] Volume preserving transformations of affine connection and conformal transformations of metric yield generalized scalar curvature Lagrangian with consistent field equations without Vanishing Weyl vector

[en] A solution of the gravitational field equations is found by using an axially symmetric metric which is asymptotically a de Sitter space metric. The general approach of Bondi, van der Burg, and Metzner as applied to the asymptotic flat-space case is used and a search is made for the necessary conditions for gravitational radiation in asymptotic de Sitter space. It is found that the character of the gravitational radiation, if it exists at all, is considerably different from that obtained in the case of asymptotic flat space. (author)

[en] Given the close ties between general relativity and geometry one might reasonably expect that quantum effects associated with gravitation might also be tied to the geometry of space-time, namely, to some sort of discreteness in space-time itself. In particular it is supposed that space-time consists of a discrete lattice of points rather than the usual continuum. Since astronomical evidence seems to suggest that the universe is expanding, the lattice must also expand. Some of the implications of such a model are that the proton should presently be stable, and the universe should be closed although the mechanism for closure is quantum mechanical. (author)

[en] Previously the author considered extensions of metric theories of gravitation with non-zero divergence of the energy momentum tensor. It is confirmed here that lack of local conservation laws does not exclude, a priori, existence of integral conservation laws. (Auth.)

[en] The variation of the field action with the scalar Lagrangian density √(-g)R is calculated with respect to the metric, torsion and non-metricity. When the non-metricity vanishes, the variation reduces to the U₄ theory of gravitation when a relativistic matter Lagrangian with minimal coupling is included. (Auth.)

[en] We examine the effect of the introduction of a six-dimensional extension of the Dirac equation on the problem of the physical meaning of the additional temporal coordinates of a (3+3) spacetime. We demonstrate that the electromagnetic field introduces a polarization of the temporal axes and that this polarization effect divides the (3+3) spacetime into six (3+1) Lorentzian subspaces. Subluminal interactions which involve fields and particles within a specified (3+1) subspace do not introduce multitemporal motion. We have therefore shown that a (3+3) formulation of the problems of subluminal and superluminal motion along with extended relativity is consistent with ordinary interactions predicted by the Dirac equation