Gravitational Field Theory Research Articles

Gravitational Topological Quantum Field Theory VersusN= 2D= 8 Supergravity and its lift toN= 1D= 11 Supergravity

In a previous work, it was shown that the 8-dimensional topological quantum field theory for a metric and a Kalb-Ramond 2-form gauge field determines N = 1 D = 8 supergravity. It is shown here that, the combination of this TQFT with that of a 3-form determines N = 2 D = 8 supergravity, that is, an untruncated dimensional reduction of N = 1 D = 11 supergravity. Our construction holds for 8-dimensional manifolds with Spin(7) \subset SO(8) holonomy. We suggest that the origin of local Poincare supersymmetry is the gravitational topological symmetry. We indicate a mechanism for the lift of the TQFT in higher dimensions, which generates Chern-Simons couplings.

ANALYSIS OF THE STATIC AND SPHERICALLY-SYMMETRIC SOLUTION IN NDL THEORY OF GRAVITATION

We investigate the static solution with spherical symmetry of a member of a recently proposed class of field theories of gravitation. In this so-called NDL theory, matter interacts with gravity in accordance with the Weak Equivalence Principle, while gravitons have a nonlinear self-interaction. It is shown that the predictions obtained from this solution agree with those of General Relativity in the three classic tests. There are potential differences in the strong-field limit, which we illustrate by proving that this theory does not allow the existence of static and spherically symmetric black holes.

The fifth dimension: Theodor Kaluza's ground-breaking idea

Theodor Kaluza (1885–1954) attracted the attention of the physical community since 1921 with his unified field theory of gravitation and electromagnetism in five dimensions. Despite Einstein's great interest in Kaluza's theory, 50 years elapsed before it contributed toward a paradigm shift in modern theoretical physics. The biography of this still unknown scientist is briefly presented along with an outline of his work in physics. A short history of the theories of unification and the dimensionality of space-time is followed by a discussion of the significance of Kaluza's five-dimensional unified theory in modern physics from the point of view of superstring and M-theory.

The fifth dimension: Theodor Kaluza's ground‐breaking idea

AbstractTheodor Kaluza (1885–1954) attracted the attention of the physical community since 1921 with his unified field theory of gravitation and electromagnetism in five dimensions. Despite Einstein's great interest in Kaluza's theory, 50 years elapsed before it contributed toward a paradigm shift in modern theoretical physics. The biography of this still unknown scientist is briefly presented along with an outline of his work in physics. A short history of the theories of unification and the dimensionality of space‐time is followed by a discussion of the significance of Kaluza's five‐dimensional unified theory in modern physics from the point of view of superstring and M‐theory.

A new application of the lunar laser retroreflectors: Searching for the “local” hubble expansion

Precise measurements of the Earth-Moon distance by the lunar laser ranging (LLR), which begun in the early 1970's, contributed significantly to geodesy, geophysics, and lunar planetology, as well as enabled astrophysicists to perform several fine tests of the relativistic gravitational field theory (General Relativity). Yet another promising application of LLR arises just now in the context of recent cosmological models, whose dynamics is substantially affected by some kinds of the dark matter (or the so-called “dark energy”) uniformly distributed in space and should, therefore, be accompanied by some residual Hubble expansion at any spatial scales, particularly, in the Earth-Moon system. The “local” Hubble expansion can be revealed by comparing the rate of increase in the lunar semi-major axis measured by LLR (which should be produced both by the well-known tidal exchange of angular momentum between the Earth and Moon and the local Hubble expansion) with the same quantity derived indirectly from astrometric data on the Earth's rotation deceleration (which is produced only by the tidal interaction). Such analysis really points to the discrepancy 1.3 cm/yr, which corresponds to the local Hubble constant H 0 (loc) = 33 ± 5 (km/s)/Mpc. This value is about two times less than at intergalactic scales but many orders of magnitude greater than was predicted in earlier theoretical works.

Generalized metrical multi-time Lagrange geometry of physical fields

Section 1 contains some physical and geometrical aspects of the generalized Lagrangian geometry of physical fields developed by Miron and Anastasiei [7], which represents the start point in our generalized metrical multi-time Lagrangian approach of the theory of physical fields. Section 2 exposes a geometrization of a Kronecker h-regular vertical metrical d-tensor G (�)(�) (i)(j) on the jet fibre bundle of order one J 1 (T,M). We emphasize that this geometrization gives a mathematical model for both the gravitational and electromagnetic field theory, in a general setting. Thus, Section 3 presents the generalized metrical multi-time Lagrange theory of electromagnetism and describes its Maxwell equations. Section 4 presents the Einstein equations which govern the generalized metrical multi-time Lagrange theory of gravitational field. The conservation laws of the gravitational field are also described in terms of generalized metrical multi-time Lagrange geometry. Section 5 gives a more natural form of the Einstein equations and of their conservation laws.

Nonsymmetric unified theory of gravitation, electromagnetism and Yang–Mills field

The recently studied new variation of Einstein's metric nonsymmetric unified field theory of gravitation and electromagnetism is enlarged to include the Yang–Mills field theory. It is shown that the antisymmetric part of the metric tensor, now a 2 × 2 matrix, can be made to describe both a field obeying Maxwell's equations and a field obeying Yang–Mills's field equations in the flat space linear approximation, thereby making its identification with the sum of a generalized electromagnetic and isotopic field strength tensors a possibly consistent procedure. The theory is shown to be free of unphysical ghost-negative energy radiative modes even when expanded on a curved Riemannian background. The Einstein–Maxwell–Yang–Mills theory is contained in the first approximation of the field equations on a curved general relativity background.

Spherically symmetric solutions of gravitational field equations in Kalb–Ramond background

Static spherically symmetric solutions in a background spacetime with torsion is derived explicitly. The solutions are shown to possess interesting features like ‘wormholes’ or ‘naked singularity’ in spacetime. The torsion considered here is identified with the field strength of a second rank antisymmetric tensor field namely the Kalb–Ramond field and the proposed solution therefore has much significance in a string inspired gravitational field theory.

Nonsymmetric unified field theory. II. Phenomenological aspects

The nonsymmetric unified field theory of gravitation and electromagnetism developed in a previous paper in vacuum is here supplemented by introducing the sources. The sources of the field, the matter energy-momentum tensor and the electromagnetic current, are introduced explicitly into the Lagrangian providing a close contact with elementary particle physics concepts in the linear approximation of the theory and an explicit form for the conservation laws. The theory is shown to be free of ghost-negative energy particles and tachyons as well. The equations of motion of test charged particles are established through the invariance of the interaction Lagrangian.

FIELD THEORIES FROM THE RELATIVISTIC LAW OF MOTION

From the relativistic law of motion we attempt to deduce the field theories corresponding to the force law being linear and quadratic in four-velocity of the particle. The linear law leads to the vector gauge theory which could be the Abelian Maxwell electrodynamics or the non-Abelian Yang–Mills theory. On the other hand, the quadratic law demands space–time metric as its potential which is equivalent to demanding the principle of equivalence. It leads to the tensor theory of gravitational field — general relativity. It is remarkable that a purely dynamical property of the force law leads uniquely to the corresponding field theories.

Gravitational Physics: Exploring the Structure of Space and Time

This book contains a report on the goals and hopes of the physics of gravitation, prepared by the Committee on Gravitational Physics of the National Research Council of USA, and is a part of the decadal survey Physics in a New Era. The Committee is formed of fifteen very distinguished scientists and is chaired by J B Hartle. Its charges were (1) to assess the achievements in gravitational physics over the last decade and (2) to identify the most promising opportunities for research in order to describe the resources necessary to realize these opportunities. It received proposals on different aspects of gravitation and requested input from the community of gravitational physics in a number of ways before preparing the report, which was reviewed later by other prestigious physicists. It begins with an Executive Summary that states the conclusions in just six pages and has three chapters: 1. Introduction, overview and recommendations; 2. Ideas and phenomena of general relativity; and 3. Achievements and opportunities in general relativity. The book is really interesting, as might be expected from the institutions and scientists that prepared it. It is easily read and states its points in a direct, expressive and clear language. Although it cannot be excluded that some lonely hunter could provide a conceptual breakthrough, the complexity of the issues involved, needing the constructive interference of approaches from many fields, as well as the necessity of taking account of new data obtained in large astrophysical observatories, suggest that very probably the recommendations of the book will articulate most of the progress over the next ten or twenty years. Chapter 2 contains a terse review of the key ideas of general relativity and of the key phenomena of gravitational physics. Although it does not offer any new ideas for people who know about these topics, it is pedagogical and appealing and is a pleasure to read. Chapter 3, with 68 pages, is divided into five parts, dedicated to: I. Gravitational waves, II. Black holes, III. Origin, evolution and fate of the universe, IV. General relativity and beyond: experimental exploration, and V. Unifying gravity and quantum theory. Each part examines successively the key questions, the achievements up to now and the opportunities that are perceived. In the 17 pages of chapter 1, the book states the goals and recommendations for the next ten years, after reviewing the achievements of the past decade and the opportunities that can be appreciated now. These goals are: to receive gravitational waves and use them to study regions of strong gravity; to explore the conditions near black holes; to measure the geometry of the universe at cosmological scales; to test the limits of Einstein's general relativity and explore for new physics; and to unify gravity and quantum theory. The recommendations are as follows. (1) Develop the LIGO scientific program with respect to the high-frequency gravitational wave window and a space-based laser interferometry facility to detect the low-frequency gravitational waves produced by the merging of supermassive black holes. (2) Study the classical and quantum theory of strong gravitational fields (both by developing analytic and numerical tools to study strong field solutions of Einstein's equations and by supporting research in quantum gravity). (3) Precision measurements: improve dramatically the tests of the equivalence principle and of the gravitational inverse square law. (4) Astronomical observations: use gamma-ray, x-ray, optical, infrared and radio telescopes to study the environments of black holes; measure the temperature and polarization fluctuations of the cosmic background radiation at scales down to the arcminute; search for relativistic binary systems; launch detectors of gamma-rays and x-ray bursts capable of detecting counterparts of LIGO events; and use supernovae and gravitational lenses to infer the distribution of dark matter. The book contains a useful and highly reliable summary of the state of the art of gravitational physics and a most authoritative set of recommendations. It is very advisable reading for researchers and teachers in gravitational physics and for all those who wish to maintain a good general knowledge of the evolution of the main ideas of physics, even outside of their particular field.

Some connections and variational principle to the Finslerian scalar-tensor theory of gravitation

A generalized scalar-tensor theory of the Finslerian gravitational field is constructed on the basis of the fibered bundle of a base manifold and consists of two G-numbers (Grassmannian noncommutative) y +, y −, playing the role of fibres. In the framework of our approach, we study: the connection structures, torsions, curvatures and the gravitational field equations derived from variational principles of the appropriate Lagrangian densities.

The velocity of gravitational waves

We examine the propagation of gravitational waves in the new field theory of gravitation recently proposed by Novello-De Lorenci-Luciane (NDL). This examination is done on a solvable case corresponding to a spherically symmetric static configuration. We show that in NDL theory the velocity of gravitational waves is lower than light velocity. We point out some consequences of this result and suggest a possible scenario for its verification.

Boundary states and black hole entropy

Black hole entropy is derived from a sum over boundary states. The boundary states are labeled by energy and momentum surface densities, and parametrized by the boundary metric. The sum over state labels is expressed as a functional integral with measure determined by the density of states. The sum over metrics is expressed as a functional integral with measure determined by the universal expression for the inverse temperature gradient at the horizon. The analysis applies to any stationary, nonextreme black hole in any theory of gravitational and matter fields.

Signals from SN 1987A in Amaldi-Weber antennas as the possible detection of scalar gravitational waves

An equation is obtained for the cross section of a metal Weber cylinder for scalar gravitational waves, which are possible within the framework of the field theory of gravitation. It is shown that the signals detected by the Amaldi and Weber antennas during the explosion of supernova SN 1987A can be interpreted as the result of the action of scalar gravitational waves on solid-state detectors. The required energy of the gravitational waves is about 1 M⊙c2. Together with the observed excess (about 1 %) of gravitational radiation from the binary system containing the pulsar PSR 1913+16, the signals from SN 1987A are the second piece of observational evidence for the actual existence of scalar gravitational waves. The present-day, third-generation, solid-state antennas are capable of detecting scalar waves from events like SN 1987A at a distance up to 5 Mpc. The expected level of the signal from SN 19931 is about 7 mK. An experimental test of the longitudinal nature of scalar waves is possible using interferometric antennas based on free masses.

Black hole pair creation and the entropy factor.

It is shown that in the instanton approximation the rate of creation of black holes is always enhanced by a factor of the exponential of the black hole entropy relative to the rate of creation of compact matter distributions (stars). This result holds for any generally covariant theory of gravitational and matter fields that can be expressed in Hamiltonian form. It generalizes the result obtained previously for the pair creation of magnetically charged black holes by a magnetic field in Einstein-Maxwell theory. The particular example of pair creation of electrically charged black holes by an electric field in Einstein-Maxwell theory is discussed in detail.

The theory of the classical gravitational field

Equations for the massive gravitational field have been derived in the framework of the special theory of relativity on the basis of the geometrization principle. Graviton mass has been shown to be crucial for the elaboration of the relativistic theory of gravitation. According to this theory, a homogeneous and isotropic universe develops in a series of alternating cycles, from high to low density, and cannot be anything other than flat. The theory predicts the presence of a large amount of latent mass in the universe and prohibits the existence of 'black holes'. Also, the theory explains all observable events so far known to occur in the Solar system.

Теория классического гравитационного поля

Теория классического гравитационного поля

Theory of the classical gravitational field and Mach's principle

Equations for a massive gravitational field are found in the framework of the special theory of relativity on the geometrization principle. The existence of a graviton mass has fundamental significance for the construction of the theory. In accordance with this theory of gravitation, a homogeneous and isotropic universe evolves cyclically from a high density to a minimum density, etc., and can only be “flat.” The theory predicts the existence of an appreciable amount of “dark” matter in the universe. The existence of “black holes” in the universe is completely ruled out. The theory explains all known observational facts in the solar system.

On the theory of gravitational field non-localized by the internal variable-V

On the theory of gravitational field non-localized by the internal variable-V