Gravitoinertial reference frames in spaces with pure radiation

A method is proposed for the construction of gravitoinertial reference frames (gravito-IRF) in spaces with pure gravitational radiation. The Penrose method of conformal inversion of spaces is used.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 19–24, April, 1977.I wish to thank V. I. Rodichev, D. D. Ivanenko, and the members of the seminar directed by them for valuable critical remarks.     

Superenergy of Gravitational Waves in the Exact Theory

Gravitational waves and radiation in the exact theory are studied in a unique framework. The observer's point of view is introduced. Some results by Lichnerowicz are generalized and interpreted in terms of reference frames. This allows us to recognize the role played by the gravitational force field in the exact generalization of Bel's superenergy flux theorem. It is also possible to recover the usual concept of wave as energy transmission, by means of a suitable superenergy scalar.     

Dynamics of a gravitational field. I

A dynamic theory of a gravitational field is constructed by analogy with electromagnetic field theory in a two-dimensional space. The main point of this paper is the determination in Einstein spaces of the analogs of inertial and quasiinertial frames of reference in twodimensional space. The possibility is discussed of interpreting the velocity field of the basis of such frames of reference as potentials of the gravitational field. This then permits a dynamic theory of the gravitational field (field equations, energy characteristics) to be constructed in Maxwellian form.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 97–103, May, 1973.In conclusion, I take this opportunity of expressing thanks to Professor V. I. Rodichev for constant attention to the work.     

Gravi-inertial reference frames in Schwarzschild and Kerr spaces

Gravi-inertial reference frames — the analogue of inertial frames in two-dimensional space — are constructed in Schwarzschild and Kerr spaces. With their help the energy, momentum, and angular momentum of these systems are determined. A form is found for writing Kerr's solution in Bondi-Sachs coordinates in the slow-rotation approximation. A new solution of Einstein's equations is found in this approximation which describes the gravitational field of a rotating and radiating source.     

Gravitons in Minkowski space-time interactions and results of astrophysical interest

A review is presented of the quantization procedures applicable to linear gravitational fields in Minkowski space-time and of various interactions processes involving gravitons. The discussion is mainly concerned with those processes that in the Feynman diagrammatic approach involve gravitons on external lines and are of particular astrophysical interest because of their contribution to background gravitational radiation in the universe. More specifically they are graviton production from particle-antiparticle annihilation, gravitational bremsstrahlung, scattering of gravitons and photoproduction. Among the topics discussed are also, the graviton-particle vertex and some of its applications, and the problem of coherent emission of gravitational radiation in the laboratory.     

A Non-geometric Relativistic Theory of Gravitation

A non-geometric relativistic theory of gravitation is developed by defining a semi-metric to replace the metric tensor as gravitational vector potential. The theory show that the energy-momentum tensor of the gravitational field belong to the gravitational source, gravitational radiation is contained in Einstein’s field equations that including the contribution of gravitational field, the real physical singularity in the gravitational field can be eliminated, and the dark matter in the universe is interpreted as the matter of pure gravitational field.     

Gravitational radiation generated by the gravitational scattering of two stars

Within the framework of general relativity, the gravitational scattering of two stars is considered with regard to the gravitational radiation effects. The angular and frequency dependence of the generated gravitational radiation is investigated by Fourier's analysis of the gravitational field in the radiation zone. The results of the numerical calculations show a strong directional dependence of the radiation in the plane of movement of the stars.     

On a new variational principle in general relativity and the energy of the gravitational field

A new variational principle based on the affine connection in space-time is proposed. This leads to a new formulation of general relativity. The gravitational field is a field of inertial frames in space-time. The metricg appears as a momentum canonically conjugate to the gravitational field. In the case of simple matter fields, e.g., scalar fields, electromagnetic fields, Proca fields, or hydrodynamical matter, the new formulation is equivalent to the traditional one. A new formulation of conservation laws is proposed.     

Gravitational radiation in asymptotic de Sitter space

A solution of the gravitational field equations is found by using an axially symmetric metric which is asymptotically a de Sitter space metric. We use the general approach of Bondi, van der Burg, and Metzner as applied to the asymptotic flat-space case and search for the necessary conditions for gravitational radiation in asymptotic de Sitter space. We find 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.     

Electromagnetic and gravitational synchrotron radiation

A brief survey of the theory of synchrotron radiation (SR) is presented, with particular attention to quantum effects in the SR spectrum. The inaccuracy of the recent paper by Latal and Erber, considering quantum corrections to the classical SR spectrum, is pointed out. Some mechanisms of generation of gravitational radiation arealso discussed: gravitational SR, creation of gravitons in annihilation processes, and plasma generation of gravitational waves.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 46–53, February, 1980.     

Gravitation in flat space-time

A previously studied Lorentz-covariant theory of gravitation is given in generally covariant form, i.e., the theory holds for arbitrary reference frames. Flat space-time is a natural condition for the conservation of energy and momentum. The energy-momentum tensor of matter and gravitation is the source of the gravitational field.     

Gravitational waves and astrophysical sources

In linear approximation to general relativity, gravitational waves can be thought of as perturbation of the background metric that propagate at the speed of light. A time-varying quadrupole of matter distribution causes the emission of gravitational waves. Application of Einsteinʼs quadrupole formula to radio binary pulsars has confirmed the existence of gravitational waves and vindicated general relativity to a phenomenal degree of accuracy. Gravitational radiation is also thought to drive binary supermassive black holes to coalescence – the final chapter in the dynamics of galaxy collisions. Binaries of compact stars (i.e., neutron stars and/or black holes) are expected to be the most luminous sources of gravitational radiation. The goal of this review is to provide a heuristic picture of what gravitational waves are, outline the worldwide effort to detect astronomical sources, describe the basic tools necessary to estimate their amplitudes and discuss potential sources of gravitational waves and their detectability with detectors that are currently being built and planned for the future.     

狭窄波束型高频引力辐射与电磁场的作用效应

从弱引力场的Einstein-Maxwell方程出发,讨论了晶体空间阵列的狭窄波束型高频引力辐射与电磁场的作用效应,并给出了扰动解。计算表明,在TT(Transvese Traceless)坐标系中,最优辐射方向的引力波束是纯十型极化的,并可使同频的电磁波产生倍频的扰动效应,使静态电磁场产生与时间成线性关系的累积扰动效应。对于任意方向上的引力辐射波束,在垂直于引力波矢的平面内仍然是纯十型极化的。在高频辐射和实验室典型尺度条件下,TT坐标系与Fermi坐标系的差异是可以忽略的。 关键词：     

Relativity,thermodynamics and entropic forces

A recent assertion that inertial and gravitational forces are entropic forces is discussed. A more conventional approach is stressed herein, whereby entropy is treated as a result of relative motion between observers in different frames of reference. It is demonstrated that the entropy associated with inertial and gravitational forces is dependent upon the well known lapse function of general relativity. An interpretation of the temperature and entropy of an accelerating body is then developed, and used to relate the entropic force to Newton's second law of motion. The entropic force is also derived in general coordinates. An expression of the gravitational entropy of in‐falling matter is then derived by way of Schwarzschild coordinates. As a final consideration, the entropy of a weakly gravitating matter distribution is shown to be proportional to the self‐energy and the stress‐energy‐momentum content of the matter distribution.     

On the possibility of a box for holding gravitational radiation in thermal equilibrium

We show that it is possible in principle to build a box which will hold gravitational radiation for a time long enough to thermalize it. The box is a thin spherical shell of charged matter with a large red shift at the surface of the shell. The radiation is kept in the box by the gravitational potential of the shell and is thermalized by the conversion between gravitational and electromagnetic radiation. We calculate the time for escape of the radiation and show that it is longer than the conversion time.     

Electromagnetic waves in the Kerr–Schild metric

A short electromagnetic wavelength approximation is used to obtain general solutions to the Maxwell equations for electromagnetic radiation in a Kerr–Schild plane gravitational wave metric. Their properties are then investigated for the specific case of a light beam in a weak, harmonic gravitational wave.     

A dispersion relation for gravitational radiation in a Schwarzschild background

A dispersion relation is derived for gravitational radiation emitted from an almost spherical object.     

On the Higgs feature of gravity

The gauge gravitation theory, based on the equivalence principle besides the gauge principle, is formulated in the fibre bundle terms. The correlation between gauge geometry on spinor bundles describing Dirac fermion fields and space-time geometry on a tangent bundle is investigated. We show that field functions of fermion fields in presence of different gravitational fields are always written with respect to different reference frames. Therefore, the conventional quantization procedure is applicable to fermion fields only if gravitational field is fixed. Quantum gravitational fields violate the above mentioned correlation between two geometries.     

Neutrino radiation in spherically-symmetric gravitational fields. III. Comparison with photon radiation fields

The gravitational properties of spherically-symmetric photon and neutrino radiation fields are compared and found to be identical. A model for the photon radiation field made up of incoherent radiation is first developed, equations for photons being required to satisfy Maxwell's equations.