Showing papers on "Gravitation published in 1978"
TL;DR: In this article, the dynamical content of the linearized field is analyzed by reducing the fourth-order field equations to separated second-order equations, related by coupling to external sources in a fixed ratio.
Abstract: Inclusion of the four-derivative terms ∫RμνRμν(−g)1/2 and ∫R2(−g)1/2 into the gravitational action gives a class of effectively multimass models of gravity. In addition to the usual massless excitations of the field, there are now, for general amounts of the two new terms, massive spin-two and massive scalar excitations, with a total of eight degrees of freedom. The massive spin-two part of the field has negative energy. Specific ratios of the two new terms give models with either the massive tensor or the massive scalar missing, with correspondingly fewer degrees of freedom. The static, linearized solutions of the field equations are combinations of Newtonian and Yukawa potentials. Owing to the Yukawa form of the corrections, observational evidence sets only very weak restrictions on the new masses. The acceptable static metric solutions in the full nonlinear theory are regular at the origin. The dynamical content of the linearized field is analyzed by reducing the fourth-order field equations to separated second-order equations, related by coupling to external sources in a fixed ratio. This analysis is carried out into the various helicity components using the transverse-traceless decomposition of the metric.
1,209 citations
TL;DR: In an attempt to find gravitational analogs of Yang-Mills pseudoparticles, this paper obtained two classes of self-dual solutions to the euclidean Einstein equations, which are free from singularities and approach a flat metric at infinity.
554 citations
TL;DR: In this article, a zeta function regularization of the one-loop term for gravity was proposed to obtain a non-trivial scaling behavior in cases in which the background metric has non-zero curvature tensor.
548 citations
TL;DR: In this article, the universe is conceived as the response of matter and the gravitational field to a spontaneous point-like disturbance, and the history unfolds in two stages, creation and free expansion.
440 citations
TL;DR: In this article, a general algorithm for the construction of gravitational axial and conformal anomalies for fields of arbitrary spin is presented, and a variety of models are then displayed in which one or both of the anomalies vanish by cancellation.
206 citations
TL;DR: In this article, a decomposition of the space of gravitational degrees of freedom in terms of which the one-loop corrections take an especially simple form is introduced. And the question of zero modes, and the fluctuations about de Sitter space are treated in detail.
188 citations
TL;DR: In this paper, the authors propose to replace the path integrals over the terms in the Taylor series by a discrete sum of the exponentials of all complex solutions of the Einstein equations, each solution being weighted by its one-loop term.
Abstract: The path-integral method seems to be the most suitable for the quantization of gravity. One would expect the dominant contribution to the path integral to come from metrics which are near background metrics that are solutions of classical Einstein equations. The action of these background metrics gives rise to a new phenomenon in field theory, intrinsic quantum entropy. This is shown to be related to the scaling behavior of the gravitational action and to the topology of the gravitational field. The quadratic terms in the Taylor series of the action about the background metrics give the one-loop corrections. In a supersymmetric theory the quartic and quadratic but not the so-called logarithmic divergences cancel to give a one-loop term that is finite without regularization. From the one-loop term one can obtain the effective energy-momentum tensor on the background metric. In the case of an evaporating black hole, the energy-momentum tensor will be regular on the future horizon. The usual perturbation expansion breaks down for quantum gravity because the higher (interaction) terms in the Taylor series are not bounded by the quadratic (free) ones. To overcome this I suggest that one might replace the path integrals over the terms in the Taylor series by a discrete sum of the exponentials of the actions of all complex solutions of the Einstein equations, each solution being weighted by its one-loop term. This approach seems to give a picture of the gravitational vacuum as a sea of virtual Planck-mass black holes.
177 citations
TL;DR: In this article, the authors compared the properties of the SU(2) Yang-Mills Instanton with those of ℂP6762 and concluded that ℆6762 may be regarded as a gravitational pseudoparticle surrounded by an event horizon.
Abstract: We compare some of the properties of ℂP
2 with those of the SU(2) Yang-Mills Instanton and conclude that ℂP
2 may be regarded as a gravitational pseudoparticle surrounded by an event horizon.
172 citations
TL;DR: Even-parity electromagnetic and gravitational linear perturbations of Oppenheimer-Snyder collapse are studied in this paper, where it is shown that exterior radiation fields develop quite similarly in the tow problems.
Abstract: Even-parity electromagnetic and gravitational linear perturbations of Oppenheimer-Snyder collapse are studied. The even-parity electromagnetic problem is shown to be identical to the analogous odd-parity electromagnetic problem. For the gravitational case, the mathematical appearance of the even-parity problem is markedly different from that for odd-parity. Numerical results are presented, however, which show that exterior radiation fields develop quite similarly in the tow problems and that previous conclusions (dominance of quasi-normal ringing, power-law tails late times) for odd-parity radiation apply equally well to the even-parity case.
133 citations
TL;DR: The self-dual metric on K3 (the manifold of Kummer's quartic surface) has 58 parameters and a physical interpretation of these is given in terms of an approximate construction of the K3 gravitational instanton from 16 Eguchi-Hanson metrics arranged in a lattice with certain identifications.
108 citations
TL;DR: In this article, the conformally invariant form of the classical gravitational action is restored, and it is shown that conformal anomalies, discovered in gravitating systems, do not affect the S matrix.
TL;DR: In this paper, the authors considered linear perturbations of black hole models by a variety of fields and derived the crucial condition th at the field be singular on the inner horizon.
Abstract: Linear perturbations of black hole models by a variety of fields are considered. Perturbing fields include the zero rest mass scalar field in the case of Reissner-Nordstrom, and gravitational, electromagnetic and zero rest mass scalar perturbation in the case of the Kerr model. The analysis deals with the Ψ 0 components (in the Newman-Penrose (1962) formalism) of non-zero spin fields. The symmetry properties of the models are used to derive the crucial condition th at the field be singular on the inner horizon. This condition is independent of the field propagation equation. Initial data are then given in terms of incoming radiation from f - is shown that there exist wellbehaved initial data sets for which the resultant fields are singular on the inner horizon. It is emphasized that this instability result is dependent only on the global symmetries and causal structure of the models considered, and is independent of the precise nature of the perturbing field.
TL;DR: In this paper, the logic of gravitational field energy localisation for static or quasi-static fields is discussed and a particular form of localisation in the case of spherical symmetry is justified by physical considerations.
Abstract: The logic of gravitational field energy localisation for static or quasi-static fields is discussed. A particular form of localisation in the case of spherical symmetry is justified by physical considerations. This form coincides with that general form presented by Moller (1952) for the case of the Schwarzschild constant-matter-density fluid but differs when one considers other equations of state.
TL;DR: In this paper, the conformal 2-structure is proposed as a way to represent the two gravitational degrees of freedom of the Einstein field equations, which is a solution to the Cauchy spacelike initial value problem.
Abstract: In this paper, we suggest that what we shall call the conformal 2‐structure may, in an appropriate coordinate system, serve to embody the two gravitational degrees of freedom of the Einstein (vacuum) field equations. The conformal 2‐structure essentially gives information concerning the manner in which a family of 2‐surfaces is embedded in a 3‐surface. We show that, formally at least, this prescription works for the exact plane and cylindrical gravitational wave solutions, for the double‐null and null‐timelike characteristic initial value problems, and for the usual Cauchy spacelike initial value problem. We conclude with a preliminary consideration of a two‐plus‐two breakup of the field equations aimed at unifying these and other initial value problems; and a discussion of some aspirations and remaining problems of this approach.
TL;DR: In this article, a general covariant formulation of the Nambu-Jona-Lasinio type for gravity and electromagnetism is presented, which is effectively equivalent to the Einstein-Weyl theory of general relativity.
Abstract: A generally covariant formulation is made for the previously proposed unified model of the Nambu-Jona-Lasinio type for gravity and electromagnetism. The gravitational and electro-magnetic fields are generated as collective excitations of fermion-antifermion pairs. The modl is shown to be effectively equivalent to the Einstein-Weyl theory of general relativity. The G-α relation, the relation between the fine structure constant and the Newtonian gravitational constant is re-derived.
TL;DR: In this paper, the quantum field theory of Einstein's general relativity is formulated in the indefinite metric Hilbert space in such a way that asymptotic fields are manifestly Lorentz covariant and the physical S-matrix is unitary.
Abstract: Quantum field theory of Einstein's general relativity is formulated in the indefinite metric Hilbert space in such a way that asymptotic fields are manifestly Lorentz covariant and the physical S-matrix is unitary. The general coordinate transformation is transcribed into a q-number transformation, called the BRS transformation. Its abstract definition is presented on the basis of the BRS transformation for the Yang-Mills theory. The BRS transformation for general relativity is then explicitly constructed. The gauge-fixing Lagrangian density and the Faddeev-Popov one are introduced in such a way that their sum behaves like a scalar density under the BRS transformation. One can then proceed in the same way as in the Kugo-Ojima formalism of the Yang-l\1ills theory to estnblish thL> unitarity of the physical S-matrix.
CERN1
TL;DR: In this paper, the spin-3 2 axial anomaly is discussed from various points of view, including the Feynman graph method, the zeta function regularization method, and the point splitting method.
TL;DR: In this paper, it is shown how this mechanism works in the case when the standard Einstein-Cartan equations are valid at a microphysical level, and some spin-spin terms remain from the averaging procedure for randomly distributed spins.
Abstract: The Einstein-Cartan theory of gravitation (“general relativity with spin”) provides a specific spin-spin contact interaction of matter, in addition to the usual long-range gravity. This new interaction enables us to prevent singularities in Cosmological models. It is shown how this mechanism works in the case when the standard Einstein-Cartan equations are valid at a microphysical level, and some spin-spin terms remain from the averaging procedure for randomly distributed spins. In contrast with the case of aligned spin distributions, it is possible to take over the isotropic and spatially homogeneous (i.e., Friedmannian) models into the Einstein-Cartan theory. These models can be made free from singularity, thanks to the self-interaction of spinning fluid.
TL;DR: In this article, the authors describe strong and gravitational interactions in a unified way by assuming covariance of physical laws under (discrete) dilatations, and describe a hierarchy of universes governed by force fields with strenghts inversely proportional to the universe radii.
Abstract: By assuming covariance of physical laws under (discrete) dilatations, we succeed in describing strong and gravitational interactions in a unified way. In terms of the (additional, discrete) « dilatational » degree of freedom, our cosmos as well as hadrons can be considered as different states of the same system, or rather assimilar systems. Moreover, a discrete hierarchy can be defined of « universes » which are governed by force fields with strenghts inversely proportional to the « universe » radii. Inside each « universe » an equivalence principle holds, so that its characteristic field can be geometrized there. Wo can thus easilyderive a whole « numerology »,i.e. relations among numbers analogous to the so-called Weyl-Eddington-Dirac « large numbers ». For instance, the « Planck mass » happens to be nothing but the (average) magnitude of thestrong charge
TL;DR: In this paper, a class of exact spherically symmetric solutions to the coupled classical field equations of $f\ensuremath{-}g$ theory were found. And they are both of Schwarzschild-plus-de Sitter type.
Abstract: We find a class of exact spherically symmetric solutions to the coupled classical field equations of $f\ensuremath{-}g$ theory. The $f$ and $g$ metrics each induce a cosmological constant in the field equations of the other, and are both of Schwarzschild-plus-de Sitter type.
TL;DR: In this article, the second-order differential equations of motion of spinning test particles (tops) were derived from a variational principle in a given gravitational background defined by a Riemannian metric and a torsion tensor.
Abstract: The (second-order differential) equations of motion of spinning test particles (tops) are derived from a variational principle in a given gravitational background defined by a Riemannian metric and a torsion tensor. The mass and (magnitude of) the spin of the top are conserved. There exists a Regge trajectory linking the mass and the spin of the top. Constants of the motion associated with Killing vectors of the metric along which the Lie derivative of the torsion tensor vanish are found.
TL;DR: In this article, the problem of quantizing the gravitational fluctuations about a symmetric vacuum background spacetime with compact Cauchy surfaces was studied and it was shown that the allowed physical states must all be invariant under the symmetry transformations of the background space.
Abstract: We study the problem of quantizing the gravitational fluctuations about a symmetric vacuum background spacetime with compact Cauchy surfaces. In the context of lowest-order perturbation theory we show that the allowed physical states must all be invariant under the symmetry transformations of the background spacetime. This constraint does not unduly restrict the range of allowed states and is consistent with temporal evolution (in the presence of a timelike symmetry) or spacial localization (for a spacelike symmetry) provided the evolution or localization is interpreted intrinsically rather than with reference to the background spacetime.
TL;DR: In this article, an infinite class of new gravitational instantons for the axial anomaly is found, consisting entirely of algebraic spin- manifolds, and the possible relation of this to the gauge theory of weak and electromagnetic interactions is explored.
TL;DR: In this article, an SP(4 and general coordinate invariant lagrangian is presented, which reduces to the well known Einstein-Cartan gravity theory in a particular gauge.
TL;DR: In this article, an observer accelerating uniformly in flat Minkowski space experiences a heat bath whose temperature is proportional to his acceleration, and the authors employ instanton techniques to re- derive a result first obtained by totally different methods.
TL;DR: In this article, the anomalies of the Euler and Hirzebruch currents, as well as the spinor axial-vector current in a given background metric are discussed.
TL;DR: In this paper, the potential of a single electron in a quasi-uniform field was derived from the partial differential equation satisfied by the electrostatic potential in terms of generalised harmonic functions.
Abstract: In a recent paper, Prof. Whittaker has discussed the effect, according to the general theory of relativity, of gravitation on electromagnetic phenomena. In particular, he has discussed electrostatics in gravitational fields of two kinds, namely (i) the field due to a single gravitating mass, in which case space-time has the metric discovered by Schwarzschild, and (ii) a limiting case of this, called a quasi-uniform field, in which the gravitational force is, in the neighbourhood of the origin, uniform. Whittaker’s general method, so far as electrostatical problems were concerned, was to solve the partial differential equation satisfied by the electrostatic potential in terms of generalised harmonic functions, and then, from these, to build up other solutions. In this way, he succeeded in finding an algebraic expression which represents the potential of a single electron in the quasi-uniform field; he did not, however, obtain a corresponding algebraic expression for the potential of an electron in the Schwarzschild field.
TL;DR: In this article, a totally gauge-invariant formulation of the linearized Einstein field equations for the most general matter-associated perturbations away from a spatially isotropic homogeneous space-time is given.
Abstract: A totally gauge-invariant formulation of the linearized Einstein field equations for the most general matter-associated perturbations away from a spatially isotropic homogeneous space-time is given. We introduce metric, stress-energy, velocity, and scalar perturbation quantities that are invariant with respect to infinitesimal coordinate transformations on the background space-time. The linearized field equations as well as the conservation equations are exhibited for the most general type of matter-associated perturbation; no guage assumptions are made. In terms of the gauge-invariant perturbations these equations become very simple. This gauge-invariant formalism is then applied to a space-time permeated by a perfect fluid.