28 Result(s)
within
English
Physics
Astrobiology
T. Singh
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Article
An anisotropic cosmological model in Brans-Dicke theory
Solutions of Brans-Dicke field equations are obtained when the source of the gravitational field is a perfect fluid with pressure equal to energy density and the metric is cylindrically symmetric of Marder-typ...
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Article
Some general results in modified Brans-Dicke cosmologies
Raychaudhuri-type equations are derived for cosmological models filled with a perfect fluid and obeying the Brans-Dicke equations with a cosmological term depending on the scalar field. In addition, some gener...
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Article
Axisymmetric stationary vacuum fields in the general scalar tensor theory
It is show that axisymmetric stationary vacuum solutions of the general scalar tensor theory of gravitation proposed by Nordvedt and later discussed by Barker and others can be obtained from the solutions of t...
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Article
Some general results in self-creation cosmologies
Raychaudhuri-type equations are written for a cosmological model filled with perfect fluid and obeying the equations of a self-creation theory recently proposed by G. A. Barber. In addition some general result...
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Article
Some results in the general scalar tensor theory
Raychaudhuri-type equations are written for a cosmological model filled with a perfect fluid and obeying the equations of general scalar-tensor theory proposed by Nordtvedt. It is found that a non-rotating cos...
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Article
A note on the kinematics of the tachyon fluid
It is shown that the kinematical parameters associated with the congruence formed by tachyonic motion can be defined in the manner of Greenberg, but not that of Ehlers. The space-like counterpart of Raychaudhu...
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Article
Some Brans-Dicke fields generated from Einstein's vacuum fields, III
In the previous papers (I and II), we have obtained exact solutions of the Brans-Dicke scalar-tensor theory in plane and cylindrically-symmetric space-times. In the present work we have obtained a more general...
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Article
Plane-symmetric universes in general relativity
Plane-symmetric solutions of Einstein's field equations in vacuum, in the presence of electromagnetic fields and with cosmological constant are explored in null coordinates. The gravitational field of an infin...
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Article
Newtonian analogue of force and motion of a free particle in the gravitational field of Kerr-de Sitter space-time
In the first part of the paper the Newtonian analogue of force for the Kerr-de Sitter metric has been investigated. To the first-order of approximation, a component of the force vector corresponds to the Newto...
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Article
Newtonian analogue of force and motion of a free particle in the gravitational field of theC-metric
In the first part of the paper the Newtonian analogue of force for theC-metric has been investigated. To the first-order of approximation in the absence of acceleration of the particle generating theC-metric, one...
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Article
A note on some static scalar-gravitational fields
In this note extending the technique developed for static fields by De (1964) to the static plane-symmetric solution of Taub (1951) and the conformastat gravitational universe of Das (1971) solutions for coupl...
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Article
Some anisotropic spatially-homogeneous cosmological models with electromagnetic field
Considering Bianchi type-I metric, cosmological models of a perfect fluid with an electromagnetic field have been obtained, using a supplementary condition between the metric potentials. The four-current is ei...
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Article
Product spaceV 2xV 2 and plane fronted waves in general projective relativity
In this paper the field equations of General Projective Relativity have been investigated in the product space ofV 2xV 2 space-time (Bertotti, 1959) and plane fronted metric of Peres (1959). It is shown that wave...
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Article
Non-static cylindrically symmetric fields in general projective relativity
Exact solutions for the vacuum field equations of General Projective Relativity of Arcidiacono (1986) are obtained for the non-static Einstein-Rosen metric (Einstein and Rosen, 1937). The nature of singulariti...
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Article
Liouville space-time in general projective relativity
Vacuum field equations of general projective relativity have been solved for Liouville space-time. Finally harmonic coordinate condition and singular behaviour of Kretschmann scalar for the solution is discussed.
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Article
Cylindrically-symmetric matter distribution with a magnetic field in Einstein-Cartan Theory
In the first part the number of independent non-vanishing components of the 3-index torsion tensorQ jk i ...
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Article
Certain vacuum Bianchi-type models in a new relativistic theory of gravitation
The vacuum Bianchi type-I, III, V, VI0 and Kantowski-Sachs models have been obtained in a new scalar-tensor theory formulated by Lau and Prokhovnik (1986) under the assumption of a certain relationship between th...
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Article
Bianchi type III and Kantowski-Sachs cosmological models in Lyra geometry
The cosmological models for Bianchi type III and Kantowski-Sachs space-time within the framework of Lyra geometry are obtained. The physical behaviour of the models have also been discussed.
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Article
Bianchi type V and VI0 cosmological models in Lyra geometry
The Bianchi type V and VI0 models have been investigated in Lyra geometry in both the cases with the gauge function β is a time dependent and β=constant. The physical behaviour of these models has been discussed.
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Article
Some Bianchi-type cosmological models in a new scalar-tensor theory
Bianchi type I, III, V, VI0, and Kantowski-Sachs type models have been investigated in a scalar tensor theory developed by Saez and Ballester (1985) and Saez (1985). The dynamical behaviour of the models has also...
