共查询到20条相似文献,搜索用时 31 毫秒
1.
A work, recently published by this journal, is discussed and the critique is presented in this same issue. Our revision of this critique is focused on two main topics: a) the suggested Taub solution and (b) the method followed to arrive at it.Reply to the comment by R. Jantzen, GRG 37 (2005) 相似文献
2.
Subhash Kak 《International Journal of Theoretical Physics》2007,46(5):1424-1430
This paper considers how the motion of an observer in an isotropic universe may be determined by measurements. This provides
a means to identify inertial frames, yielding a simple resolution to the twins paradox of relativity theory in such a universe.
We propose that isotropy is a requirement for a frame to be inertial; this makes it possible to relate motion to the large
scale structure of the universe. 相似文献
3.
M. de Campos 《General Relativity and Gravitation》2003,35(5):899-906
We study a model that the entropy per particle in the universe is constant. The sources for the entropy are the particle creation and a decaying term. We find exact solutions for the Einstein field equations and show the compatibility of the model with respect to the age and the acceleration of the universe. 相似文献
4.
A generalized Kerr-NUT type metric is considered in connection with Einstein field equations corresponding to perfect fluid
plus a pure radiation field. A general scheme for obtaining the exact solutions of these field equations is developed. Two
physically meaningful particular cases are investigated in detail. One gives the field of a radiating Kerr particle embedded
in the Einstein universe. The other solution may probably represent a deSitter-like universe pervaded by a pure radiation
field. 相似文献
5.
D. R. K. Reddy R. L. Naidu S. Atchuta Rao 《International Journal of Theoretical Physics》2008,47(4):1016-1020
We have investigated a simple axially symmetric inflationary universe in the presence of mass less scalar field with a flat
potential. To get an inflationary universe, we have considered a flat region in which potential V is constant. Some physical properties of the universe are also discussed. 相似文献
6.
The group velocity of gravitational waves in a flat Friedman–Robertson–Walker universe is investigated. For plane waves with
wavelength well inside the horizon, and a universe filled with an ideal fluid with the pressure to density ratio less than
1/3, the group velocity is greater than the velocity of light. As a result, a planar pulse of gravitational waves propagating
through the universe during the matter/dark energy dominated era arrives to the observer with the peak shifted towards the
forefront. For gravitational waves emitted by inspiralling supermassive black holes at the edge of the observable universe,
the typical shift that remains after the effects of nonplanarity are suppressed is of order of 10 ps. 相似文献
7.
R.P. Mondaini 《Physics letters. A》1982,93(2):61-62
It is shown that if we apply the Ansatz recently proposed by Oh and Teh to find a static Yang-Mills field in a plane symmetric universe, we get simply the vacuum Taub solution or the maxwellian Patnaik solution. In addition, we have shown that there are no plane wave solutions. 相似文献
8.
Spherically symmetric non-static higher dimensional metrics are considered in connection with Einstein’s field equations.
Two exact solutions are derived. One of them corresponds to a mixture of perfect fluid and pure radiation field and represents
higher dimensional Vaidya metric in the cosmological background of Einstein static universe. The other corresponds to a pure
radiation field and represents higher dimensional Vaidya metric in the background de Sitter universe. For both of these solutions,
the cosmological constant is taken to be non-zero. Many known solutions are derived as particular cases. 相似文献
9.
In this paper, we have considered the curved universe which is filled by tachyonic field. We have found the exact solutions
for the field, pressure, density, and scale factor and some cosmological parameters. In such universe, we have investigated
the role of tachyonic field in different stages of k for the evolution of the universe. Finally we draw the graphs for the scale factor, Hubble’s parameter, energy density, pressure,
acceleration parameter, equation of state and potential for the different values of k. Also we obtained the exact form of field which shows that the tachyonic field has the kink form. 相似文献
10.
We study an anisotropic Bianchi-I universe in the presence of a phantom field and a cosmological constant. Cosmological solutions
are obtained when the kinetic energy of the phantom field is of the order of anisotropy and dominates over the potential energy
of the field. The anisotropy of the universe decreases and the universe transits to an isotropic flat FRW universe accommodating
the present acceleration. A class of new cosmological solutions is obtained for an anisotropic universe in case an initial
anisotropy exists which is bigger than the value determined by the parameter of the kinetic part of the field. Later, an autonomous
system of equations for an axially symmetric Bianchi-I universe with phantom field in an exponential potential is studied.
We discuss the stability of the cosmological solutions.
相似文献
11.
M. Farasat Shamir Atrooba Saeed 《Journal of Experimental and Theoretical Physics》2017,125(6):1065-1070
The purpose of this document is to investigate the universe in f(G) gravity. A wgeneral static plane symmetric space-time is chosen and exact solutions are explored using a viable f(G) gravity model. In particular, power and exponential law solutions are discussed. In addition, the physical relevance of the solutions with Taub’s metric and anti-deSitter space-time is shown. Graphical analysis of energy density and pressure of the universe is done to substantiate the study. 相似文献
12.
A five dimensional Kaluza-Klein inflationary universe is investigated in the presence of massless scalar field with a flat
potential. To get an inflationary universe a flat region in which potential V is constant is considered. Some physical and kinematical properties of the universe are also discussed. 相似文献
13.
The Einstein universe is a simple model describing a static cosmological spacetime, having a constant radius and a constant curvature, and, as is well known, it does not describe our universe. We propose a model which is an extension of Einstein's. Our metric, havingR × S
3 topology, describes a nonisotropic homogeneous closed (finite) universe of Bianchi type IX. This metric is similar to that of Taub, but is simpler. Unlike the Taub solution (which is a cosmological extension of the NUT solution), however, the universe described by our metric contains matter. Like the Taub metric, our metric has two positive constants (, T). The gravitational red shift calculated from our metric is given. Similarly to the Schwarzschild metric, which has a singularity atr = 2m, this metric has the same kind of singularity att = 2. The maximal extension of the coordinates in our metric is fairly analogous to that of the Schwarzschild metric. 相似文献
14.
In dealing with the wavefunction of the universe there is a debate on the various proposals about the boundary condition of the wavefunction of the universe. At present we have three proposals, namely, the Hartle-Hawking proposal, the tunneling proposal and the Linde proposal. Recently it has been argued that the operator ambiguity factor has a decisive role in deciding the consequences of the various wavefunction at the zero scale factor region. In the present paper we discuss the role of operator ordering in the light of wormhole dominance proposal proposed by one of the authors and compare the results with that of others obtained earlier. We present an interpretation of operator ordering as a contribution of some sort of matter fields and discuss the role of complex path WKB analysis in avoiding the initial singularity and allowing us to incorporate the contribution of wormhole in the wavefunction of the universe. 相似文献
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17.
The Wheeler–DeWitt equation of arbitrary Hartle–Hawking factor ordering for several minisuperspace universe models, such as the pure gravity Friedmann–Robertson–Walker and Taub ones, is mapped onto the dynamics of corresponding classical oscillators. The latter ones are studied by the classical Ermakov invariant method, which is a natural approach in this context. For the more realistic case of a minimally coupled massive scalar field, one can study, within the same type of approach, the corresponding squeezing features as a possible means of describing cosmological evolution. Finally, we comment on the analogy with the accelerator physics. 相似文献
18.
We find exact eigenvalues and eigenfunctions of relativistic massless scalar particle conformally coupled to a background Einstein universe. 相似文献
19.
ZHANGDe-Hai 《理论物理通讯》2001,35(5):635-638
A new “twice loose shoe“ method in the Wheeler-DeWitt equation of the universe wavefunction on the cosmic scale factor a and a scalar field φ is suggested,We analyze both the affections coming from the tunnelling effect of α and the potential well effect of φ,and obtain the initial values α0 about a primary closed universe which is born with the largest probability in the quantum manner,Our result is able to overcome the “large field difficulty“ of the universe quantum creation probabiltiy with only tunnelling effect.This new born universe has to suffer a startup of inflation,and then comes into the usual slow rolling inflation.The universe with the largest probalility maybe has a “gentle“ inflation of an eternal chaotic infltion.this depends on a new parameter q which describes the tunnelling character. 相似文献
20.
B. G. Sidharth 《Foundations of Physics Letters》2004,17(5):503-506
Extending the result of a previous paper, wherein elementary particles were considered to be an array of Planck scale oscillators, we show that the universe itself is the normal mode of a set of Planck scale oscillators. 相似文献