Showing papers on "Gravitational field published in 1985"
Journal Article•
744 citations
TL;DR: This paper describes both the particular program and the methodology underlying such speedups that reduced the running time of a large problem $(N = 10,000)$ by a factor of four hundred.
Abstract: The simulation of N particles interacting in a gravitational force field is useful in astrophysics, but such simulations become costly for large N. Representing the universe as a tree structure wit...
592 citations
TL;DR: In this paper, the form of the gauge and gravitational anomalies in quantum field theories may be derived from classical index theorems, and the relation between various forms of the anomaly present in the literature is also clarified.
454 citations
TL;DR: In this paper, it is shown that if ideal observations are available, they are insufficient to determine the space-time structure on the past light cone of the observer; however, in the cosmological case they are precisely necessary and sufficient to determine a spacetime geometry on the light cone and in its causal past (down to where caustics or curps first occur).
287 citations
TL;DR: In this article, the parity-violating effective action for theories of fermions coupled to external gauge and gravitational fields in odd dimensions is computed exactly, and the action is then used to compute gauge and gravity anomalies in even dimensions.
255 citations
Journal Article•
TL;DR: In this article, a self-consistent problem involving the behavior of small perturbations in an isotropic homogeneous universe filled with a scalar field is considered and solutions describing the evolution of perturbation in the case of an arbitrary scalar-field potential are obtained.
Abstract: A self-consistent problem involving the behavior of small perturbations in an isotropic homogeneous universe filled with a scalar field is considered Solutions describing the evolution of perturbations in the case of an arbitrary scalar-field potential are obtained
228 citations
Book•
01 Jan 1985
TL;DR: In this article, the authors divided their book into the following chapters: Geometry and Gravitation, the Formalism of General Relativity, Gravitational Field Equations, Three Classical Tests of Einstein's Theory, Elements of Cosmology, Relativistic Cosmological Models, Non-Static Models of the Universe; Gravitational Waves; Dense and Collapsed Matter; The Einstein-Cartan Theory; The Strong Gravity Theory; Gauge Theory of Gravity; Supergravity, and Gravitational Theory in the Language of Exterior Forms
Abstract: This book is divided into the following chapters: Contents: Geometry and Gravitation; The Formalism of General Relativity; Gravitational Field Equations; The Three Classical Tests of Einstein's Theory; Elements of Cosmology; Relativistic Cosmological Models; Non-Static Models of the Universe; Gravitational Waves; Dense and Collapsed Matter; The Einstein-Cartan Theory; The Strong Gravity Theory; Gauge Theory of Gravity; Supergravity; Gravitational Theory in the Language of Exterior Forms.
167 citations
TL;DR: In this article, data from the Voyager and Pioneer flybys of Jupiter and the Galilean satellites are employed to characterize the Jovian magnetic field and the effects of the Io torus on transmissions.
Abstract: Data sets from the Voyager and Pioneer flybys of Jupiter and the Galilean satellites are employed to characterize the Jovian magnetic field and the effects of the Io torus on transmissions. Both optical and Doppler radio data are considered, except for periods when the Jovian radiation environment disturbed the oscillator stability of the radio transmitters. Account is taken of small accelerations of the spacecraft by tidal forces of a single rising satellite, density differences in the Great Red Spot producing a columnar gravitational change, and three unknown objects in the inner Jovian system. Correction parameters are developed for the effects on the S-band data induced by the Jovian plasmasphere inwards from the Io torus. Calculations are then made of the planet and satellite masses, gravity harmonic coefficients, and orientation of the rotational pole. Large reductions in the uncertainties in previous mass estimates are obtained.
127 citations
01 Jan 1985
TL;DR: Gravitational wave antennas have sensitivity many orders greater than procedures for direct measurement of the geometry of spacetime as mentioned in this paper, and they can be used for direct measurements of the geometrical geometry of space.
Abstract: Gravitational wave antennas have sensitivity many orders greater than procedures for direct measurement of the geometry of spacetime
119 citations
TL;DR: In this article, a canonical formalism of ADM is used to define the Hamiltonian to order c −4 in the instantaneous part of a gravitational interacting many-particle system and to leading quadrupole order in the coupling of the system with the dynamical degrees of freedom of the gravitational field.
116 citations
TL;DR: In this article, the equivalence of Kramer-Neugebauer and HKX transformations was proved and the double Kerr solution was constructed by means of four HKX transformation, and the resulting solution was analyzed in detail.
TL;DR: In this paper, a general theory for the figures of satellites, which are synchronously rotating in the gravitational field of a planet, is developed to the first approximation, and the Love Numbers, figure parameters, and gravitational moments for two-and three-layer models of the Galilean satellites, Titan, and Saturn's icy satellites are calculated.
TL;DR: In this article, a systematic examination of the relationship between the Earth's gravity field and topography in each of the earth's major ocean basins is presented, with the objective to summarize the principal results which have been obtained so far in the Pacific Ocean.
Abstract: The study of the earth's gravitational field has provided one of the principal methods for the determination of the structure of the outer layers of the earth. A project has been undertaken which involves the systematic examination of the relationship between the earth's gravity field and topography in each of the earth's major ocean basins. The first part of the project was concerned with the compilation, reduction, and analysis of the available surface-ship gravity and bathymetry and satellite-derived geoid data in the oceans of the earth. The present paper has the objective to summarize the principal results which have been obtained so far in the Pacific Ocean.
TL;DR: In this article, the separation of gravity field recovery and orbit determination is tested numerically with a simplified gravity field (with a purely zonal spherical harmonic expansion) up to degree 300, for both the potential coefficients and for the orbit an almost exact recovery is attained after two iteration steps.
Abstract: An orbiting gradiometer measures simultaneously several gravity quantities, ideally all six second-order derivatives of the gravitational potential. These contain information on the orbit, on the structure of the gravity field, and on the attitude of the space-craft. Due to the availability of several components simultaneously it is possible to separate orbit determination from attitude or gravity field recovery. This facilitates the analysis of the gradiometer measurements and allows the use of the principles of fast spherical harmonic analysis. The separation of gravity field recovery and orbit determination is tested numerically with a simplified gravity field (with a purely zonal spherical harmonic expansion) up to degree 300. For both the potential coefficients and for the orbit an almost exact recovery is attained after two iteration steps.
TL;DR: In this article, Bianchi I cosmological models consisting of a fluid with both bulk and shear viscosity are studied and it is shown how the dynamical importance of the shear and the fluid density change in the course of evolution.
Abstract: Bianchi I cosmological models consisting of a fluid with both bulk and shear viscosity are studied It is shown how the dynamical importance of the shear and the fluid density change in the course of evolution Exact solutions with an equation of state p=ρ for a stiff fluid are also obtained in several special cases, assuming the viscosity coefficients to be the power functions of the density The results are, in some relevant cases, compared with those of Belinskiǐ and Khalatnikov (1976) in the asymptotic limits and are seen to agree with them in that the models start with ρ=0 at the beginning and evolve with the creation of matter by the gravitational field, finally approaching the Friedmann universe
TL;DR: The Einstein-Maxwell field equations of general relativity are used to construct a Lorentz model of an electron as an extended body consisting of pure charge and no matter and the mass of the electron is associated with its Schwarzschild gravitational mass.
Abstract: We show how the Einstein-Maxwell field equations of general relativity can be used to construct a Lorentz model of an electron as an extended body consisting of pure charge and no matter. In contrast with Lorentz's approach using inertial mass, we associate the mass of the electron with its Schwarzschild gravitational mass. The Schwarzschild mass of an extended charged body as seen at infinity arises from the charge as well as the matter that the extended body possesses. The field equations for a Lorentz-type pure-charge extended electron are obtained by setting the matter terms equal to zero in the field equations for a spherically symmetric charged perfect fluid. Several explicit solutions to the pure-charge field equations are examined.
TL;DR: In this article, it was shown that in linearized general relativity it is impossible to construct a detector by the use of which the quantum state of the linearized gravitational field could be reliably determined.
Abstract: I show that in linearized general relativity it is impossible to construct a detector by the use of which the quantum state of the linearized gravitational field could be reliably determined. This is because there is no material satisfying the positive energy condition which can serve as a good conductor or absorber of gravitational radiation over a finite range of frequencies. If this property is true of the full theory then one can conclude that a certain proportion of both the energy and information carried by a gravitational wave is irreversibly lost, and that there is a correspondingintrinsic entropy associated with any distribution of gravitational radiation.
TL;DR: In this article, the authors examined the similarity requirements for a single particle moving in a fluid and showed that the behavior of the model in a uniform ng field is not similar to that in the 1g field unless the Reynolds number in both conditions is less than unity.
Abstract: Two simulations are involved when a centrifuge is used to test models. First, the behaviour of the model in a uniform ng field is assumed to be similar to that of the prototype. Then the centrifuge is assumed to produce an equivalent ng gravitational field. For most static problems, the centrifuge does produce an equivalent ng gravitational field, but for some dynamic problems involving saturated soil these assumptions can break down. When the soil particles and fluid are moving relative to one another, the behaviour in the ng field is not similar to that in the 1g field unless the Reynolds number in both conditions is less than unity. Since this is a special circumstance, the centrifugal behaviour is not similar to that of the prototype in most cases. To illustrate this, the similarity requirements are examined for a single particle moving in a fluid. If different fluids are used in the model and prototype, then the difference in densities must also be accounted for.
01 Sep 1985
TL;DR: In this paper, the concept of the conventional Airy/Heiskanen isostatic model is investigated from scratch, based on the harmonic analysis of the topographic-isostatic potential.
Abstract: : The concept of the conventional Airy/Heiskanen isostatic model is investigated from scratch, based on the harmonic analysis of the topographic-isostatic potential. First and higher order approximations for those coefficients are discussed and rule of thumb formulas given. The estimated frequency transfer function between the power spectrum of the observed gravitational field and the power spectrum implied by the isostatic model strongly suggests a smoothing of the compensation surface according to Vening Meinesz with a smoothing operator of Gaussian bell-shaped type, and a depth of compensation of about 24 km. A proof of equivalence of using a standard Airy/Heiskanen model with a larger comepnsation depth and a corresponding Poisson smoothed Vening Meinesz model at a smaller depth has been given for the case of linear approximation, yielding an entirely new interpretation of recent isostatic models. An iterative least-squares process has been designed which provided parameter estimates of that isostatic model in best possible agreement with the observed gravitational potential of the earth. Based on these parameters a set of harmonic coefficients of the topographic-isostatic potential, complete up to degree and order 180 was computed. Several maps of topography-isostasy implied geoidal heights are presented for comparison. Keywords: Isostasy; Harmonic analysis and synthesis; Fast Fourier transform; Smoothing operators; Operators(Mathematics).
TL;DR: The existence of the three-parametric family of collinear-libration points in the photo-gravitational three-body problem is proved in this article, and the number and situation of these points are determined with respect to the system parameters.
Abstract: The existence of the three-parametric family of the collinear-libration points in the photo-gravitational three-body problem (differing from the classical one by the addition to the gravitational field the light repulsion force-field) is proved The number and situation of these points are determined with respect to the system parameters Their stability to a first approximation is investigated It is shown that oppositly to the classical problem the internal collinear libration-points may be stable in some domain of parameter-space
TL;DR: In this paper, a new solution of the vacuum Einstein equations by means of the rank-zero Hoenselaers-Kinnersley-Xanthopoulos transformations was obtained by taking as seed metric the static axisymmetric Erez-Rosen metric.
TL;DR: The required coordinate transformations are performed in this paper and some general features of the matter profiles and spacetime geometry in this gauge are discussed.
Abstract: The exact solution for the collapse from rest of an initially homogeneous dust sphere (Oppenheimer-Snyder collapse) provides a convenient test-bed calculation for fully general-relativistic time-dependent numerical codes which evolve matter in strong gravitational fields. Such codes are usually based on the Arnowitt-Deser-Misner 3+1 formalism, for which maximal time slicing and isotropic spatial coordinates often prove to be desirable gauge choices to constrain the lapse and shift functions. To be useful as a check on these numerical schemes, the entire Oppenheimer-Snyder solution must then be expressed in this gauge. We perform the required coordinate transformations in this paper and discuss some general features of the matter profiles and spacetime geometry in this gauge.
TL;DR: In this paper, a procedure for the construction of the gravitational multipoles is proposed, and the full metric is given in the case of a mass possessing a quadrupole moment.
Abstract: A procedure is proposed for construction of the gravitational multipoles. The full metric is given in the case of a mass possessing a quadrupole moment.
TL;DR: This paper develops the concept of the ''stretched horizon,'' which will be vital for both the electromagnetic and gravitational aspects of the formalism, and it presents several model problems illustrating the interaction of dynamical electromagnetic fields with stationary black-hole horizons.
Abstract: This paper is part of a series of papers with the aim of developing a complete self-consistent formalism for the treatment of electromagnetic and gravitational fields in the neighborhood of a black-hole horizon. In this membrane formalism, the horizon is treated as a closed two-dimensional membrane lying in a curved three-dimensional space, and endowed with familiar physical properties such as entropy and temperature, surface pressure and viscosity, and electrical conductivity, charge, and current. This paper develops the concept of the ''stretched horizon,'' which will be vital for both the electromagnetic and gravitational aspects of the formalism, and it presents several model problems illustrating the interaction of dynamical electromagnetic fields with stationary black-hole horizons: The field of a test charge in various states of motion outside the Schwarzschild horizon is analyzed in the near-horizon limit, where the spatial curvature may be ignored and the metric may be approximated by that of Rindler. This analysis elucidates the influence of the horizon on the shapes and motions of electric and magnetic field lines when external agents move the field lines in arbitrary manners. It also illustrates how the field lines interact with the horizon's charge and current to produce an exchange of energymore » and momentum between the external agent and the horizon. A numerical calculation of the dynamical relaxation of a magnetic field threading a Schwarzschild black hole is also presented, illustrating the ''cleaning'' of a complicated field structure by a black-hole horizon, and elucidating the constraints on the location of the stretched horizon.« less
TL;DR: In this paper, a relativistic theory of gravitation (RTG) is constructed on the basis of the special relativity and geometrization principle, in which a gravitational field is treated as the Faraday-Maxwell spin-2 and spin-0 physical field possessing energy and momentum.
Abstract: In the present paper a relativistic theory of gravitation (RTG) is unambiguously constructed on the basis of the special relativity and geometrization principle In this a gravitational field is treated as the Faraday-Maxwell spin-2 and spin-0 physical field possessing energy and momentum The source of a gravitational field is the total conserved energy-momentum tensor of matter and of a gravitational field in Minkowski space In the RTG the conservation laws are strictly filfilled for the energy-momentum and for the angular momentum of matter and a gravitational field The theory explains the whole available set of experiments on gravity By virtue of the geometrization principle, the Riemannian space in our theory is of field origin, since it appears as an effective force space due to the action of a gravitational field on matter The RTG leads to an exceptionally strong prediction: The universe is not closed but just “flat” This suggests that in the universe a “missing mass” should exist in a form of matter
TL;DR: The Casimir energy of the gravitational field in certain Kaluza-Klein theories is computed and the one-loop quantum effective potential of thegravity field on the background manifold (Minkowski space) x (N-sphere) is evaluated as a function of the radius of the N- Sphere.
Abstract: The Casimir energy of the gravitational field in certain Kaluza-Klein theories is computed. Specifically, the one-loop quantum effective potential of the gravitational field on the background manifold (Minkowski space)\ifmmode\times\else\texttimes\fi{}(N-sphere) is evaluated as a function of the radius of the N-sphere. (N is restricted to be odd for technical reasons.) Minima of the (real part of the) potential for which the observed cosmological constant is zero are found numerically for N=13, 15, 17, 19, and 21. The potential has an imaginary part which is attributed to ``tachyonic'' terms in the mode sum, although it is argued that the Faddeev-Popov ghost modes do not contribute to this imaginary part.
TL;DR: An associated frame-dependent velocity field is defined which illustrates the solitonic character of these gravitational solitons in the classical sense.
Abstract: We discuss a multisoliton solution to Einstein's equations in vacuum. The solution is interpreted as many gravitational solitons propagating and colliding on a homogeneous cosmological background. Following a previous letter, we characterize the solitons by their localizability and by their peculiar properties under collisions. Furthermore, we define an associated frame-dependent velocity field which illustrates the solitonic character of these gravitational solitons in the classical sense.
TL;DR: The solitary vortex solution for the set of nonlinear equations describing low-frequency fluid motion in a magnetized plasma was shown to exist in this article, and the existence of the solitary vortex is shown to be equivalent to the singular vortex solution.
Abstract: The solitary vortex solution is shown to exist for the set of nonlinear equations describing low‐frequency fluid motion in a magnetized plasma.
TL;DR: The ultralocal representation of gravity is used to obtain a quasiclassical approximation for the evolution of wave functionals towards the initial singularity and it is indicated how this can be used to prepare the state of the gravitational field in the immediate neighborhood of the singularity.
Abstract: The ultralocal representation of gravity is used to obtain a quasiclassical approximation for the evolution of wave functionals towards the initial singularity. The whole dynamical content of this process is encoded in the successive asymptotic scatterings of Kasner wave functions by the gravitational potential term V = gR. It is indicated how this can be used to prepare the state (density operator) of the gravitational field in the immediate neighborhood of the singularity.