Nonstationary cosmological models with rotation

Cosmological models containing rotation and expansion have become of great interest since the publication of Birch. In the present paper we obtain a wide class of exact solutions describing an expanding and rotating universe. Sources are taken to be an anisotropic or ideal fluid, a massless scalar field, and a radiation field.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 48–51, March, 1988.     

Self-consistent solutions for cosmological models with rotation

A wide spectrum of new results is obtained describing homogeneous motionless cosmological models with rotation in which causality is not violated. Exact solutions are also given for cosmological models describing an expanding and rotating universe. Sources in the obtained solutions are an anisotropic or ideal fluid, a massless complex scalar field, the electromagnetic field, a radiation field, and various combinations of these sources.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 5–10, June, 1988.     

Gravitational collapse of phantom fluid in (2 + 1)-dimensions

In this paper, we solve Einsteins’ field equations for a circularly symmetric anisotropic fluid, with kinematic self-similarity of the first kind, in (2 + 1)-dimensional spacetimes. Considering the case where the radial pressure vanishes, we show that there exists a solution that represents the gravitational collapse of an anisotropic fluid, and the collapse will finally form a black hole, even if the fluid is constituted by phantom energy.     

Field Effects in Condensed Media on Polarized Absorption

The existence of anisotropic local field perturbation on electronic absorption is proved by non-zero linear dichroism of isotropic chromophores (Mo(CO)₆) in anisotropic environment. Two sources of such effects are possible: a) perturbation of the electronic energy levels in the chromophore by the static electric solvent field (= Stark effect) or, in case of anisotropic polarizable or dipolar molecules, similar effects involving molecular orientation, and b) dielectric effects on the effective radiation field. The latter effect was considered by various models: The Lorentz field model predicts an effect with wrong sign, it also yields too large a magitude if the anisotropy of the field is considered. If no local field correction is made and the anisotropy only operates in the radiation intensity a result more in agreement with experiment is obtained. By using the Onsager-Böttcher model one may take into account specific properties of the absorbing molecule, like anisotropy in α/r³ where α is its polarizability and r its Onsager radius.     

Kasner Cosmological Models with Two-Fluid Source in General Relativity

In this paper we present Bianchi type-I metric of the Kasner form describing two-fluid source of the universe in general relativity. In Kasner cosmological models one fluid is a radiation field modeling the cosmic microwave background, while the other is a matter field, modeling material content of the universe. The radiation and matter content of the universe are in interactive phase. We have also presented anisotropic, homogeneous nature of Kasner cosmological models with two-fluid. The behavior of fluid parameters and kinematical parameters of the models are also discussed.     

Nonstationary Gödel-type cosmological model

We construct a nonstationary, rotating, causal Gödel-type cosmological model filled with a massless complex scalar field, an anisotropic fluid with distributed scalar field charge, and a radiation field, taking into account heat flow.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 62–66, January, 1990.In conclusion, the author expresses thanks to the participants in Prof. D. D. Ivanenko's seminar for discussion of the results of the work.     

Spherically symmetric free fall collapse

The general dynamical equations for spherical gravitational collapse are derived by introducing the eigenvalue of the conformal Weyl tensor in the 2-2 component of the Einstein tensor and assuming the material content of the models to be a perfect fluid. Since this eigenvalue is coupled always with the material energy density, it has been interpreted as theenergy density of the free gravitational field whose presence is related with anisotropy and inhomogeneity. As a particular case, the collapse of a spherically symmetric dust (zero pressure) with vanishing radial acceleration (free fall collapse) is discussed. It is shown that the model is inhomogeneous with non-vanishing shear of the congruence of world lines of the dust particles. The model contains gravitational radiation by Szekere’s criterion since both shear invariant and the spatial gradient of density are non-vanishing. This is in contrast to the Oppenheimer-Synder model for which both the above mentioned characteristics are absent. A particular solution which is anisotropic and inhomogeneous has been given to prove the emission of gravitational radiation by the freely falling dust and in this case the energy density of the free gravitational field contains a typeN term superposed on the coulombian field.     

Zur Greenschen Funktion optisch anisotroper Medien

Green's Function of Optically Anisotropic Media The time-fouriertransformed dyadic Green's function is calculated in the far-field-approximation for optically anisotropic media. To this end the time- and space-fouriertransformed Green's tensor-function is represented by dyadic products of the eigenvectors of the homogeneous Fresnel's equation, and the transformation back into space is done in the asymptotic limit by the stationary phase integration method. As an application the radiation field of an electric dipole in an optically anisotropic medium is evaluated. All results are discussed in the case of uniaxial crystals.     

Radiation of a relativistic electron in the case of planar channeling in a crystal

The spectral and polarization-angular properties of the radiation of an ultrarelativistic electron are investigated in general form in the case of planar channeling in an anisotropic crystal. It is shown that to describe the characteristics of the radiation it is sufficient to know only the value of the effective field (potential) on the trajectory axis of the channeled electron.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 23–26, March, 1981.     

The Bianchi IX cosmological models

Two cosmological models for the Bianchi IX metric are constructed. These include the following sources of gravitation: 1) a co-moving anisotropic liquid, non-comoving dust, and a scalar field; 2) an anisotropic liquid, pure radiation, and a scalar field. The kinematic parameters of the models are found.     

A nonstationary cosmological model with rotation in the Einstein-Cartan theory

Within the Einstein—Cartan theory framework, a nonstationary causal cosmological model with a Gödel type metric is constructed for the case when the sources are: the Weissenhoff anisotropic fluid, pure radiation, and heat flux. The model is characterized by expansion, rotation, shift, and acceleration.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 90–94, August, 1993.     

Cosmological Models in Barber's Second Self-Creation Theory

An attempt has been taken to solve the field equations of Barber's second self creation theory with a perfect fluid in an inhomogeneous anisotropic Locally rotationally symmetric Bianchi type I space-time where the metric potentials are arbitrary functions of x and t. Because of the mathematical complexities, for particular forms of metric potentials vacuum, Zeldovich and radiation models are determined. It is shown that -vacuum model does not exist with the above choice of metric potentials. Even though the geometrical structure of Zeldovich and radiation models are the same and reveal same physical behaviour but they are governed by different Barber's scalar.     

Dynamical System Analysis for Anisotropic Universe in Brans-Dicke Theory

In this work, we have studied the Brans-Dicke (BD) cosmology in anisotropic models. We present three dimensional dynamical system describing the evolution of anisotropic models containing perfect fluid and BD scalar field with self-interacting potential. The relevant equations have been transformed into the dynamical system. The critical points and the corresponding eigen values have been found in radiation, dust, dark energy, ΛCDM and phantom phases of the universe. The natures and the stability around the critical points have also been investigated.     

Optical vortices and topological effects in coiled fibers with combined anisotropy

The propagation of optical vortices in coiled anisotropic elliptical fibers is studied. The structure of high-order modes and their propagation constants are determined. The possibility of the generation of TE and TM modes from optical vortices with a unit topological charge in weakly anisotropic coiled fibers is demonstrated. The topological effects that arise upon the propagation of radiation along strongly anisotropic elliptical coiled fibers are investigated. It is established that topological effects are suppressed by anisotropy in the case of the propagation of l = 1 modes; the effects are manifested in these fibers in the form of the rotation of the field intensity distribution by a solid angle spanned by the light trajectory only for certain combinations of l > 1 modes.     

介质球的各向异性瑞利散射

基于电磁场的多尺度理论,研究了各向异性介质球内、外电场的规律,导出了各向异性目标散射场的表达式,得到了各向异性介质目标散射振幅、散射截面等的解析表达式,并对其正确性进行了检验.仿真结果表明:各向异性介质球的散射具有偶极辐射的特点,介电常量越大,产生的偶极矩也愈大,散射也越强.其结果可为各向异性目标监测、各向异性光散射研究等提供理论支持.     

Quantization of the radiation field in an anisotropic dielectric medium

There are both loss and dispersion characteristics for most dielectric media. In quantum theory the loss in medium is generally described by Langevin force in the Langevin noise (LN) scheme by which the quantization of the radiation field in various homogeneous absorbing dielectrics can be successfully actualized. However, it is invalid for the anisotropic dispersion medium. This paper extends the LN theory to an anisotropic dispersion medium and presented the quantization of the radiation field as well as the transformation relation between the homogeneous and anisotropic dispersion media.     

Spatial correlations and degree of polarization in homogeneous electromagnetic fields

We consider stationary electromagnetic fields modeled as superpositions of unpolarized and angularly uncorrelated plane waves and show that in anisotropic case the electric cross-spectral tensor is proportional to the imaginary part of the Green tensor. This is as for blackbody radiation, but here the field need not be in thermal equilibrium. We also evaluate the degree of polarization for a homogeneous but nonisotropic field for which the plane waves propagate within a cone of angles. The results are compared with the known polarization properties of blackbody radiation.     

Two-Fluid Anisotropic Cosmological Model with Variable G and Λ

Two-fluid anisotropic Bianchi type-III cosmological model is investigated with variable gravitational constant G and cosmological constant Λ in the framework of Einstein’s general relativity. In the two-fluid model, one fluid represents the matter content of the universe and another fluid is chosen to model the cosmic microwave background radiation. The dynamics of the anisotropic universe with variable G and Λ are discussed. We also discussed in detail the behavior of associated fluid parameters and kinematical parameters.     

Fluid spacetimes admitting covariantly constant vectors and tensors

Spacetimes admitting a covariantly constant vector and satisfying the Einstein field equations for a perfect fluid, a viscous heat-conducting fluid, or an anisotropic fluid are studied. It is found that the only possible perfect fluid spacetimes are the Einstein static universe and stiff-matter spacetimes with an isolated spatial co-ordinate, while the possible viscous fluid and anisotropic fluid spacetimes, although more abundant than their perfect fluid counterparts, must satisfy a number of strong restrictions. Examples illustrating most of the various possible situations are given. The paper concludes with a study of covariantly constant second-rank tensors in fluid spacetimes; the only possible solutions that do not also admit a covariantly constant vector are restricted to 2+2 spacetimes.     

Two-Fluid Cosmological Models in Bianchi Type-V Space-Time

We have presented anisotropic, homogeneous two-fluid cosmological models using Bianchi type-V space-time. Here one fluid represents the matter content of the universe and another fluid is chosen to model the CMB radiation. The radiation and matter content of the universe are in interactive phase. Also we have discussed the behavior of fluid parameters and kinematical parameters.