共查询到20条相似文献,搜索用时 0 毫秒
1.
Hui-Qing Lu Li-Ming Shen Guo-Hong Yang Y. Y. Lai K. S. Cheng 《International Journal of Theoretical Physics》2002,41(5):939-951
We apply the theory developed in quantum cosmology to a model of charged generalized Brans–Dicke gravity. This is a quantum model of gravitation interacting with a charged Brans–Dicke type scalar field which is considered in the Pauli frame. The Wheeler–DeWitt equation describing the evolution of the quantum Universe is solved in the semiclassical approximation by applying the WKB approximation. The wave function of the Universe is also obtained by applying both the Vilenkin-like and the Hartle–Hawking-like boundary conditions. We then make predictions from the wave functions and infer that the Vilenkin's boundary condition is more reasonable in the Brans–Dicke gravity models leading a large vacuum energy density at the beginning of the inflation. 相似文献
2.
Adrian Kent 《Foundations of Physics》2012,42(3):421-435
3.
Abraham Espinoza-García J. Socorro Luis O. Pimentel 《International Journal of Theoretical Physics》2014,53(9):3066-3077
We use one of the simplest forms of the K-essence theory and apply it to the anisotropic Bianchi type IX cosmological model, with a barotropic perfect fluid modeling the usual matter content. We show that the most important contribution of the scalar field occurs during a stiff matter phase. Also, we present a canonical quantization procedure of the theory which can be simplified by reinterpreting the scalar field as an exotic part of the total matter content. The solutions to the Wheeler-DeWitt equation were found using the Bohmian formulation Bohm (Phys. Rev. 85(2):166, 1952) of quantum mechanics, employing the amplitude-real-phase approach Moncrief and Ryan (Phys. Rev. D 44:2375, 1991), where the ansatz for the wave function is of the form Ψ(? μ )=χ(?)W(? μ ) \(e^{- S(\ell ^{\mu })},\) , where S is the superpotential function, which plays an important role in solving the Hamilton-Jacobi equation. 相似文献
4.
The Bruns–Dicke theory with a scalar field related to the quantum spinor matter is discussed [1]. The quantum Friedmann cosmology is studied. A solution to the equations of motion describing the quantum Friedmann Universe is examined for stability for the case of a flat model of the Universe. A different exact analytical solution to these equations is derived. 相似文献
5.
Simon Davis 《General Relativity and Gravitation》2000,32(3):541-551
The quantum cosmology of a higher-derivative gravity theory arising from the heterotic string effective action is reviewed. A new type of Wheeler–DeWitt equation is obtained when the dilaton is coupled to the quadratic curvature terms. Techniques for solving the Wheeler–DeWitt equation with appropriate boundary conditions shall be described, and implications for semiclassical theories of inflationary cosmology will be outlined. 相似文献
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By regarding the vacuum as a perfect fluid with equation of state p = -, de Sitter's cosmological model is quantized. Our treatment differs from previous ones in that it endows the vacuum with dynamical degrees of freedom, following modern ideas that the cosmological term is a manifestation of the vacuum energy. Instead of being postulated from the start, the cosmological constant arises from the degrees of freedom of the vacuum regarded as a dynamical entity, and a time variable can be naturally introduced. Taking the scale factor as the sole degree of freedom of the gravitational field, stationary and wave-packet solutions to the Wheeler-DeWitt equation are found, whose properties are studied. It is found that states of the Universe with a definite value of the cosmological constant do not exist. For the wave packets investigated, quantum effects are noticeable only for small values of the scale factor, a classical regime being attained at asymptotically large times. 相似文献
8.
We illustrate the crucial role played by decoherence (consistency of quantum histories) in extracting consistent quantum probabilities
for alternative histories in quantum cosmology. Specifically, within a Wheeler-DeWitt quantization of a flat Friedmann-Robertson-Walker
cosmological model sourced with a free massless scalar field, we calculate the probability that the universe is singular in
the sense that it assumes zero volume. Classical solutions of this model are a disjoint set of expanding and contracting singular
branches. A naive assessment of the behavior of quantum states which are superpositions of expanding and contracting universes
suggests that a “quantum bounce” is possible i.e. that the wave function of the universe may remain peaked on a non-singular
classical solution throughout its history. However, a more careful consistent histories analysis shows that for arbitrary
states in the physical Hilbert space the probability of this Wheeler-DeWitt quantum universe encountering the big bang/crunch
singularity is equal to unity. A quantum Wheeler-DeWitt universe is inevitably singular, and a “quantum bounce” is thus not
possible in these models. 相似文献
9.
利用推广的Hartle-Hawking假设,研究了4+2D维Einstein-Maxwell量子宇宙,计算了微超空间波函数的近似解.发现当D≤2时存在与观测宇宙相符合的暴胀解. 相似文献
10.
O. O. Novikov 《Physics of Particles and Nuclei Letters》2018,15(4):353-356
We consider the possibility to solve the issues of the phantom field cosmology by means of the PT-symmetric quantum theory. The Born–Oppenheimer approximation is applied to the Wheeler–DeWitt equation to study the inhomogeneous fluctuations over the homogeneous minisuperspace. The evolution of the longitudinal inhomogeneous modes in WKB-time is described using a time-dependent pseudo-Hermitian effective Hamiltonian. 相似文献
11.
本文发展了Schommers的时间观点,定义了时间,尤其是表征量子系统光散射的散射时间和共振散射时间。通过散射时间本征态的假定实现了散射时间的量子化,得到了量子化的共振散射时间。对原子的弹性光散射和Raman散射的成功应用推出了原子和原子的价电子逐级电离所形成的离子的所有原子能级的普适近似公式。 相似文献
12.
The existence of a Noether symmetry for a given minisuperspace cosmological model is a sort of selection rule to recover classical behaviours in cosmic evolution since oscillatory regimes for the wave function of the universe come out. The so-called Hartle criterion to select correlated regions in the configuration space of dynamical variables can be directly connected to the presence of a Noether symmetry and we show that such a statement works for generic extended theories of gravity in the framework of minisuperspace approximation. Examples and exact cosmological solutions are given for nonminimally coupled and higher-order theories. 相似文献
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14.
Subenoy Chakraborty Nabajit Chakravarty 《International Journal of Theoretical Physics》2000,39(1):153-157
For an FRW model with a minimally coupled scalar field having hyperbolic(exponential) potential we evaluate the wave function both by solving theWheeler-Dewitt (WD) equation and by evaluating the path integral. The WDequation is solved in configuration as well as in momentum space, while thepath integral is evaluated by dividing the lapse integral into a number of pieces. 相似文献
15.
It is shown that the incorporation of the Logunov coupling equations results in a nonzero Hamiltonian, which allows the problem of time of quantum gravitation theory to be solved outside the framework of traditional approaches. 相似文献
16.
I make a review on the aplications of the Bohm-de Broglie interpretation of quantum mechanics to quantum cosmology. In the framework of minisuperspaces models, I show how quantum cosmological effects in Bohms view can avoid the initial singularity, and isotropize the Universe. In the general case, I enumerate the possible structures of quantum space and time. 相似文献
17.
M. Aguero J. A. S. Aguilar C. Ortiz M. Sabido J. Socorro 《International Journal of Theoretical Physics》2007,46(11):2928-2934
In this paper we present the noncommutative Bianchi Class A cosmological models coupled to barotropic perfect fluid. The commutative
and noncommutative quantum solution to the Wheeler–DeWitt equation for any factor ordering, to the anisotropic Bianchi type
II cosmological model are found, using a stiff fluid (γ=1). In our toy model, we introduce noncommutative scale factors, is say, we consider that all minisuperspace variables q
i
does not commute, so the simplectic structure was modified. 相似文献
18.
How the time evolution which is typical for classical cosmology emerges from quantum cosmology? The answer is not trivial because the Wheeler-DeWitt equation is time independent. A framework associating the quantum Hamilton-Jacobi to the minisuperspace cosmological models has been introduced in Fathi et al. (Eur. Phys. J. C 76, 527 2016). In this paper we show that time dependence and quantum-classical correspondence both arise naturally in the quantum Hamilton-Jacobi formalism of quantum mechanics, applied to quantum cosmology. We study the quantum Hamilton-Jacobi cosmology of spatially flat homogeneous and isotropic early universe whose matter content is a perfect fluid. The classical cosmology emerge around one Planck time where its linear size is around a few millimeter, without needing any classical inflationary phase afterwards to make it grow to its present size. 相似文献
19.
T. R. Mongan 《General Relativity and Gravitation》2001,33(8):1415-1424
A simple and surprisingly realistic model of the origin of the universe can be developed using the Friedmann equation from general relativity, elementary quantum mechanics, and the experimental values of , c, G and the proton mass m
p. The model assumes there are N space dimensions (with N > 6), and the potential constraining the radius r of the invisible N – 3 compact dimensions varies as r
4. In this model, the universe has zero total energy and is created from nothing. There is no initial singularity. If space-time is eleven dimensional, as required by M theory, the scalar field corresponding to the size of the compact dimensions inflates the universe by about 26 orders of magnitude (60 e-folds). If H
0 = 65 km sec–1 Mpc–1, the energy density of the scalar field after inflation results in = 0.68, in agreement with recent COBE and Type SNe Ia supernova data. 相似文献
20.
A. García W. Guzmán M. Sabido J. Socorro 《International Journal of Theoretical Physics》2006,45(12):2483-2496
Using the factorization approach of quantum mechanics, we obtain a family of isospectral scalar potentials for power law inflationary cosmology. The construction is based on a scattering Wheeler-DeWitt solution. These iso-potentials have new features, they give a mechanism to end inflation, as well as the possibility to have new inflationary epochs. The procedure can be extended to other cosmological models.
PACS numbers: 02.30.Jr; 04.60.Ds; 04.60.Kz; 98.80.Cq. 相似文献