Singularities and Isotropy in a Brans-dicke Bianchi-type Vii Universe
نویسنده
چکیده
We study the dynamical effects in the scale factors due to the scalar φ-field at the early stages of a supposedly anisotropic Universe expansion in connection with the problem of the initial singularity in the scalar-tensor cosmology of Jordan-Brans-Dicke. This is done by considering the behaviour of the general analytical solutions for the homogeneous model of Bianchi type VII in the vacuum case. We conclude that the Bianchi-VII 0 model shows an isotropic expansion and that its only physical solution is equivalent to a Friedman-Robertson-Walker spacetime whose evolution begins in a singularity and ends in another; moreover, we obtain that the general Bianchi-VII h (with h = 0) models show strong curvature singu-larities that produces a complete collapse of the homogeinity surfaces to a 2-plane, to a string-like one-dimensional manifold, or to a single point.
منابع مشابه
Isotropic evolution of a JBD anisotropic Bianchi universe
Abstract. I study the dynamical effects due to the Brans-Dicke scalar φ-field at the early stages of a supposedly anisotropic Universe expansion in the scalar-tensor cosmology of Jordan-Brans-Dicke. This is done considering the behaviour of the general solutions for the homogeneous model of Bianchi type VII in the vacuum case. I conclude that the Bianchi-VII0 model shows an isotropic expansion ...
متن کاملLRS Bianchi type-V Universe with Variable Modified Chaplygin Gas in a Scalar Tensor Theory of Gravitation
The spatially homogeneous and anisotropic LRS Bianchi type-V Universe filled with variable modified Chaplygin gas in the framework of Brans-Dicke [1] scalar-tensor theory of gravitation has been studied. To obtain a determinate solution of the field equations we have used the condition that scalar field (φ) is a function of average scale factor. Some physical and kinematical properties of the m...
متن کاملHolographic energy density in the Brans-Dicke theory
We study cosmological applications of the holographic energy density. Considering the holographic energy density as a dynamical cosmological constant, we need the Brans-Dicke theory as a dynamical framework instead of general relativity. In this case we use the Bianchi identity as a consistency relation to obtain physical solutions. It is shown that the future event horizon as the IR cutoff pro...
متن کاملar X iv : g r - qc / 9 31 20 25 v 1 1 5 D ec 1 99 3 Curvature and Flatness in a Brans - Dicke Universe
The evolution of a universe with Brans-Dicke gravity and nonzero curvature is investigated here. We present the equations of motion and their solutions during the radiation dominated era. In a Friedman-Robertson-Walker cosmology we show explicitly that the three possible values of curvature κ = +1, 0,−1 divide the evolution of the Brans-Dicke universe into dynamically distinct classes just as f...
متن کاملFluctuations of the gravitational constant induced by primordial bubbles.
We consider the classical fluctuations of the gravitational constant generated by bubbles in the inflationary universe. For extended inflation, we demonstrate numerically how and how large fluctuations are produced during bubbleexpansion. The amplitude of the fluctuations depends on the Brans-Dicke parameter ω: if ω is of the order of unity, the amplitude becomes of the order of unity within on...
متن کامل