Showing papers on "Gravitation published in 1975"
TL;DR: In this article, it was shown that the long-wavelength structure of quantum gravitation is the same as that of the classical Einstein action, without assuming the existence of an underlying tensor field.
219 citations
TL;DR: In this article, the Lagrangian equations of motion for a spinning particle having arbitrary multipole structure in arbitrary external fields are derived and the complete system of field equations can be recovered from a fourdimensional action integral representing a polarized dust-like medium interacting with an arbitrary set of fields.
Abstract: The general form of the Lagrangian equations of motion is derived for a spinning particle having arbitrary multipole structure in arbitrary external fields. It is then shown how these equations, together with the complete system of field equations can be recovered from a fourdimensional action integral representing a polarized dustlike medium interacting with an arbitrary set of fields. These general results are then specialized to the case of Einstein-Maxwell fields in order to obtain the general-relativistic extension of Lorentz's dielectric theory.
141 citations
TL;DR: In this article, the existence of a general helicity-rotation coupling for electromagnetic waves propagating in the field of a slowly rotating body and in the Goedel universe is demonstrated.
Abstract: The existence of a general helicity-rotation coupling is demonstrated for electromagnetic waves propagating in the field of a slowly rotating body and in the Goedel universe. This coupling leads to differential focusing of circularly polarized radiation by a gravitational field which is detectable for a rapidly rotating collapsed body. The electromagnetic perturbations and their frequency spectrum are given for the Goedel universe. The spectrum of frequencies is bounded from below by the characteristic rotation frequency of the Goedel universe. If the universe were rotating, the differential focusing effect would be extremely small due to the present upper limit on the anisotropy of the microwave background radiation.
87 citations
TL;DR: The ECSK theory as mentioned in this paper introduces a new gravitational spin-spin contact interaction which is shown to be repulsive between Dirac particles whose spins are aligned and attractive when opposed, and the presence of a Dirac field as source for the torsion causes a positive "effective mass" term in the energy condition of the generalized singularity theorem.
Abstract: General relativity with spin and torsion [the Einstein-Cartan-Sciama-Kibble (ECSK) theory] provides a more complete account of local gauge invariance with respect to the Poincar\'e group than is possible in Einstein's general relativity. The ECSK theory introduces a new gravitational spin-spin contact interaction which is here shown to be repulsive between Dirac particles whose spins are aligned and attractive when spins are opposed. The presence of a Dirac field as source for the torsion causes a positive "effective mass" term in the energy condition of the generalized singularity theorem for this theory. The spin-spin interaction enhances rather than opposes singularity formation, in contrast with previous results for a convective spinning dust distribution. The strength of the interaction depends on number density, and for electron densities in excess of $\overline{\ensuremath{\rho}}\ensuremath{\simeq}{10}^{47}$ g${\mathrm{cm}}^{\ensuremath{-}3}$, can cause particle pair production.
86 citations
TL;DR: In this paper, it was shown that spontaneous symmetry treaking implies a finite cosmological term in the Einstein equation for gravity, and the present theories of weak and e.m. interactions disagree violently with the experimental limit on such a finite term unless an ad-hoc counter curvature is introduced.
Abstract: It is noted that spontaneous symmetry treaking implies
a finite cosmological term in the Einstein equation for
gravity. The present theories of weak and e.m. interactions
disagree violently with the experimental limit on such a
term unless an ad-hoc counter curvature is introduced.
82 citations
71 citations
TL;DR: In this paper, a plug-in-and-grind formalism for calculating the gravitational waves emitted by any system with weak internal gravitational fields is presented. But the formalism assumes that the internal forces have negligible influence on the system's motions.
Abstract: This paper derives and summarizes a 'plug-in-and-grind' formalism for calculating the gravitational waves emitted by any system with weak internal gravitational fields. If the internal fields have negligible influence on the system's motions, the formalism reduces to standard 'linearized theory'. Independent of the effects of gravity on the motions, the formalism reduces to the standard 'quadrupole-moment formalism' if the motions are slow and internal stresses are weak. In the general case, the formalism expresses the radiation in terms of a retarded Green's function for slightly curved spacetime and breaks the Green's function integral into five easily understood pieces: direct radiation, produced directly by the motions of the source; whump radiation, produced by the 'gravitational stresses' of the source; transition radiation, produced by a time-changing time delay ('Shapiro effect') in the propagation of the nonradiative 1/r field of the source; focusing radiation, produced when one portion of the source focuses, in a time-dependent way, the nonradiative field of another portion of the source; and tail radiation, produced by 'back-scatter' of the nonradiative field in regions of focusing.
57 citations
TL;DR: A conformal invariant theory of gravitation is proposed in this article, which matches General Relativity in the classical limit and implies a dynamical origin for mass and a selection rule on “elementary” matter constituents.
49 citations
TL;DR: The information-theoretic process physics provides an explanation of space as a quantum foam system in which gravity is an inhomogeneous flow of the quantum foam into matter.
Abstract: The new information-theoretic Process Physics provides an explanation of space as a quantum foam system in which gravity is an inhomogeneous flow of the quantum foam into matter. Here an analysis of date from seven experiments demonstrates that absolute motion relative to space has been observed by Michelson and Morley (1887), Miller (1925/26), Illingworth (1927), Joos (1930), Jaseja et al (1963), Torr and Kolen (1981), and by DeWitte (1991). The Dayton Miller data also reveals the in-flow of space into the sun. The data reveals a new form of gravitational waves, predicted by the new theory of gravity in the accompanying paper ‘Gravity as Quantum Foam In-Flow’.
45 citations
TL;DR: The information-theoretic process physics as discussed by the authors provides an explanation of space as a quantum foam system in which gravity is an inhomogeneous flow of the quantum foam into matter.
Abstract: The new information-theoretic Process Physics provides an explanation of space as a quantum foam system in which gravity is an inhomogeneous flow of the quantum foam into matter. The older Newtonian and General Relativity theories for gravity are analysed. It is shown that Newtonian gravity may be written in the form of an in-flow. General Relativity is also analysed as an in-flow, for those cases where it has been tested. An analysis of various experimental data demonstrates that absolute motion relative to space has been observed by Michelson and Morley, Miller, Illingworth, Jaseja et al, Torr and Kolen, and by DeWitte. The Dayton Miller and Roland DeWitte data also reveal the in-flow of space into matter which manifests as gravity. The experimental data suggests that the in-flow is turbulent, which amounts to the observation of a gravitational wave phenomena. A new in-flow theory of gravity is proposed which passes all the tests that General Relativity was claimed to have passed, but as well the new theory suggests that the so-called spiral galaxy rotation-velocity anomaly may be explained without the need of `dark matter'. Various other gravitational anomalies also appear to be explainable. Newtonian gravity appears to be strictly valid only outside of spherically symmetric matter systems.
TL;DR: In this paper, the authors considered the focussing of light by gravitational "lenses" (stars) and derived a finite estimate of the gainq on the optical axis (r»0) with an account of diffraction of light.
Abstract: The purpose of the present communication is to consider the focussing of light by gravitational ‘lenses’ (stars). Finite estimates of the gainq on the optical axis (r»0) can be obtained with an account of diffraction of light.
TL;DR: In this paper, the divergence of the energy-momentum tensor is assumed to be nonzero and a class of theories with consistent field equations and gauge conditions as well as compatibility with the Newtonian limit of the conservation laws are proposed.
Abstract: Assuming that the divergence of the energy-momentum tensor is nonzero leads to a class of theories with consistent field equations and gauge conditions as well as compatibility with the Newtonian limit of the conservation laws. Both the Einstein and the Brans-Dicke theories are used as models, but the extension to other viable theories such as vector-metric and two-metric theories is possible. One particularly interesting theory emerges that agrees with the ordinary Brans-Dicke theory except for the post-Newtonian parameter zeta sub 2, which predicts nonconservation of total momentum. Unfortunately, no accurate experimental limits for this parameter are known. It thus remains for future experiments in lunar-laser ranging to test this theory.
TL;DR: In this paper, the degenerate cases of conformal flatness and decomposability of space-time have been solved for the Kilmister-Yang equations for unphysical metrics.
Abstract: I solve, in principle, the Kilmister-Yang equations for the degenerate cases of conformal flatness and decomposability of space-time. The unphysical metrics discussed by Pavelle belong to these degenerate classes. Perhaps using the methods outlined here it will be possible to determine if these "unphysical" metrics are isolated examples or if they are typical of such "geometric-degenerate" classes.
TL;DR: The field equations of Rosen's bi-metric theory of gravitation were solved exactly as mentioned in this paper, and the solutions are the same as in the author's theory of gravity, however, these solutions are incompatible with Rosen's conservation laws and his second (flat) metric.
Abstract: The field equations of Rosen's bi-metric theory of gravitation [1] are solved exactly. The solutions are the same as in the author's theory of gravitation [2]. These solutions are, however, incompatible with Rosen's conservation laws and his second (flat) metric. Incompatibility with the conservation laws arises in second order. Incompatibility with the flat metric arises in first order but only for time-dependent fields. Rosen's theory is defensible only as a static first order theory and predicts the red shift light deflection and time-delay correctly.
01 Jan 1975
TL;DR: Physical principles of gravitation are enumerated, including gravitational and inertial forces, weight and mass, weightlessness, size and scale effects, scale limits of gravitational effects, and gravity as biogenic factor as discussed by the authors.
Abstract: Physical principles of gravitation are enumerated, including gravitational and inertial forces, weight and mass, weightlessness, size and scale effects, scale limits of gravitational effects, and gravity as biogenic factor. Statocysts, otolithic organs of vertebrates, gravity reception in plants, and clinostat studies for gravitation orientation are reviewed. Chronic acceleration is also studied, as well as physiology of hyper and hypodynamic fields. Responses of animals to a decreased acceleration field are examined, considering postural changes, work capacity, growth, and physiologic deadaptation.
TL;DR: In this article, a critical analysis of the observations made by Einasto et al. regarding the masses of galaxies is presented, and it is concluded that there is no independent observational evidence that the masses in these cases are much larger than those derived in the investigation of single galaxies.
Abstract: A critical analysis of the observations made by Einasto et al. and Ostriker et al. (1974) regarding the masses of galaxies is presented. The criticism centers on the assumption of gravitational binding in calculating the masses. Suppositions regarding halos surrounding galaxies; noncircular motions in outer spirals; physical bindings between our Galaxy and the six dwarf elliptical galaxies near it; and the masses of double galaxies and clusters are analyzed, and it is concluded that there is no independent observational evidence that the masses in these cases are very much larger than those derived in the investigation of single galaxies. Relative and random velocities within and between galaxies are discussed, and no indication is found for equipartition of energy between systems of different masses or for alteration of velocity dispersion by the formation and evolution of physical groupings, except for the rich clusters.
TL;DR: In this paper, the birth of the planets is discussed as a consequence of the combined action of collisions, differential rotation and gravitational interaction, and it turns out that the birth is caused by a combination of collisions and interactions.
Abstract: Perturbations and gravitational encounters are incorporated into the statistical theory of Keplerian orbits. The birth of planets is discussed as an application of the theory. It turns out to be a consequence of the combined action of collisions, differential rotation and gravitational interaction.
TL;DR: In this article, the maximum mass of a static cold neutron star is calculated according to the bimetric gravitation theory and according to general relativity theory for an assumed equation of state containing two parameters.
Abstract: The maximum mass of a static cold neutron star is calculated according to the bimetric gravitation theory and according to the general relativity theory for an assumed equation of state containing two parameters. For a certain choice of the parameters the bimetric maximum mass is found to be 8.1 M/sub sun/, while that of general relativity is 1.46 m/sub sun/, the ratio being about 5.6. Changing the parameters changes the masses, but their ratio is nearly constant for a wide range of parameter values. It is pointed out that the process of gravitational collapse in the bimetric theory (which does not admit black holes) is quite different from that in general relativity and may lead to considerable energy emission. (AIP)
TL;DR: The Backus-Gilbert inversion technique as mentioned in this paper allows a rational trade-off between accuracy and resolution, and kernels associated with the physics of the problem indicate a resolution comparable to that of surface waves.
Abstract: The knowledge that a gravity anomaly is due to an edge effect is sufficient to resolve the inherent ambiguity of the inverse potential problem. Thus given the gravity field across the contact between two laterally uniform structures, the density difference between the adjacent sections can be calculated by means of integral transforms operating on the data. The Backus-Gilbert inversion technique allows a rational trade-off between accuracy and resolution. The kernels associated with the physics of the problem indicate a resolution comparable to that of surface waves.
TL;DR: In this article, the absence of certain non scale-invariant counterterms in Einstein-Yang-Mills (or Maxwell) theory is traced instead to invariance under vector field duality rotations.
TL;DR: In this article, it is shown how it is possible to construct a Lagrangian which contains a fundamental length, by selecting a class of motions of the string, which gives rise to a spin tower of zeromass particles.
Abstract: With the aid of the ideas suggested by the string model, the possibility of describing nonhadrons by a geometrical approach is studied. It is shown how it is possible to construct a Lagrangian which contains a fundamental length, by selecting a class of motions of the string. The quantization of the model gives rise to a spin tower of zeromass particles. The interaction among these states is realized in analogy with the theory of Mandelstam for the interacting strings. The vertices for the lower spin states are studied in some detail. It is shown that in order to get the correct electromagnetic and gravitational interactions the fundamental length √α′ must be of the order of 10−33 cm. This choice of √α′ gives a very great value for the three-scalar coupling constant. This fact allows some speculation on the possibility to interpret these scalars as the constituents of the hadrons.
TL;DR: The possibility of obtaining high gravitational redshifts from static massive objects is investigated in an attempt towards finding a satisfactory explanation of the redshifting of the QSO s. Following Bondi's approach, equilibrium configurations of the core and envelope type are discussed within the framework of general relativity as discussed by the authors.
Abstract: The possibility of obtaining high gravitational redshifts from static massive objects is investigated in an attempt towards finding a satisfactory explanation of the redshifts of the QSO s . Following Bondi's approach, equilibrium configurations of the core and envelope type are discussed within the framework of general relativity. Gravitational redshifts from the center of the core, from the core-envelope boundary, and from the surface of the object are calculated in a variety of cases, and their dependence on the equation of state is studied. In a possible application of these models to QSO s , the emission is considered to arise from an optically thin central region surrounded by an exterior which lets through a fraction of the emitted light. The mass of such an object can be estimated from the emission line data, as discussed with the example of 3C9.
01 Jan 1975
TL;DR: In this paper, the authors describe the motions of Newtonian gravitational systems near triple collision, and describe the motion of a Newtonian system near a triple collision with the Sun and the Earth.
Abstract: : The author describes the motions of Newtonian gravitational systems near triple collision.
TL;DR: In this article, the authors investigated explicit solutions of the Brans-Dicke equations and found that, in the solutions presented, the material energy density never becomes infinite-either the spatial volume collapses or the gravitational 'constant' shows singular behaviour according as one adopts one or the other of the two units discussed by Dicke.
Abstract: In the background of somewhat conflicting results about the possibility of nonsingular cosmological solutions of the Brans-Dicke equations, this article investigates some explicit solutions of these equations. It is found that, in the solutions presented, the material energy density never becomes infinite-either the spatial volume collapses or the gravitational 'constant' shows singular behaviour according as one adopts one or the other of the two units discussed by Dicke. While such situations are obtained with the equation of ·state p=Ep(E= a constant ;rf1/3), the constant aJ in Brans-Dicke equations has to be given a negative value contrary to observational requirement. § I. Introduction In course of investigation of the approach to singularity in Brans-Dicke cosmology, Nariai 1l claimed that for p = p there exist solutions (belonging to the Bianchi type I group) in which there is no singularity and the material energy density p remains finite at all epochs. Such singularity-free solutions occurred for O< (2w + 3) <1/3, where w is the coupling constant in the Brans Dicke Lagrangian. As the corresponding values of w would give perihelion motion in significant contradiction to observational data, Nariai considered the solutions unacceptable. Nevertheless, Nariai's result seems surprising for the following reasons: It is well known that in the Brans-Dicke theory considered in terms of Dicke's revised units, 2l the Einstein equations remain valid with a constant gravitational 'constant' and only the energy momentum tensor is aug mented by that due to the scalar field. The energy momentum tensor A1,. due to the massless Brans-Dicke scalar field is give by
01 Jan 1975
TL;DR: Two different versions of the Green's function for the scalar wave equation in weakly curved spacetime are compared and contrasted; and their mathematical equivalence is demonstrated in this article.
Abstract: Two different versions of the Green's function for the scalar wave equation in weakly curved spacetime (one due to DeWitt and DeWitt, the other to Thorne and Kovacs) are compared and contrasted; and their mathematical equivalence is demonstrated. The DeWitt-DeWitt Green's function is used to construct several alternative versions of the Thorne-Kovacs post-linear formalism for gravitational-wave generation. Finally it is shown that, in calculations of gravitational bremsstrahlung radiation, some of our versions of the post-linear formalism allow one to treat the interacting bodies as point masses, while others do not.
01 Jan 1975
TL;DR: In this paper, the authors studied the non-singular Bianchi models of the universe filled with a spinning fluid in the framework of the Einstein-Cartan theory of gravitation, assuming that the models admit a group of motions simply transitive on three-surface orthogonal to the world lines of the substratum.
Abstract: Homogeneous models of the universe filled with a spinning fluid are studied in the framework of the Einstein-Cartan theory of gravitation. It is assumed that the models admit a group of motions simply transitive on three- surfaces orthogonal to the world lines of the substratum. For certain group types, the field equations are partially integrated. The models of the Bianchi types I, VII$sub 0$, V are shown to be nonsingular, provided the influence of spin exceeds that of shear, and an equation of state satisfies some physically reasonable conditions. (auth)
TL;DR: The exact solution of the Lifshitz equations governing the cosmological evolution of an initial fluctuation is presented in this paper, which is valid for any equation of state where the pressure equals the total energy density times the square of the sound velocity.
Abstract: The exact solution of the Lifshitz equations governing the cosmological evolution of an initial fluctuation is presented. Lifshitz results valid for squares of the sound velocity equal to zero and 1/3 are extended in closed form to any equation of state where the pressure equals the total energy density times the square of the sound velocity. The solutions embody all the results found previously for special cases of the square of the sound velocity. It is found that the growth of any initial fluctuation is only an exponential function of time with an exponent of not more than 4/3 and is insufficient to produce galaxies unless the initial fluctuation is very large. A possible way to produce very large initial fluctuations by modifying the equation of state by including gravitational interactions is also examined. It is found that a phase transition can occur at baryonic density of 1 nucleon per cubic Planck length or equivalently, at a time of about 10 to the -43rd power sec. At those early times, the masses allowed by causality requirements are too small to be of interest in galaxy formation.