scholarly journals TACHYONIC UNIVERSES IN PATCH COSMOLOGIES WITH Ω > 1

2009 ◽  
Vol 24 (30) ◽  
pp. 2445-2458 ◽  
Author(s):  
SERGIO DEL CAMPO ◽  
RAMÓN HERRERA ◽  
JOEL SAAVEDRA ◽  
PEDRO LABRAÑA ◽  
CARLOS LEIVA
Keyword(s):  
General Relativity ◽  
General Treatment ◽  
Inflationary Universe ◽  
Tachyonic Field ◽  
Astronomical Observations ◽  
Universe Models

In this paper we study closed inflationary universe models by means of a tachyonic field. We described a general treatment for created a universe with Ω > 1 in patch cosmology, which is able to represent General Relativity, Gauss–Bonnet or Randall–Sundrum patches. We use recent data from astronomical observations to constrain the parameters appearing in our model.

scholarly journals CLOSED INFLATIONARY UNIVERSE MODELS IN BRANE WORLD COSMOLOGY

2005 ◽  
Vol 14 (05) ◽  
pp. 861-872 ◽  
Author(s):  
SERGIO DEL CAMPO ◽  
RAMÓN HERRERA ◽  
JOEL SAAVEDRA
Keyword(s):  
General Relativity ◽  
Scalar Field ◽  
Brane World ◽  
Inflationary Universe ◽  
Closed Universe ◽  
Cosmological Context ◽  
The One ◽  
Universe Models ◽  
Einstein’S General Relativity

In this article we study closed inflationary universe models proposed by Linde in a brane world cosmological context. In this scenario we determine and characterize the existence of a closed universe, in presence of one self-interacting scalar field with an inflationary stage. We have found that our model, which takes into account a Brane World Cosmology, is less restrictive than the one that uses standard Einstein's General Relativity cosmology.

scholarly journals Inflationary universe models and clustering of quasar red shifts

1986 ◽  
Vol 119 ◽  
pp. 509-510
Author(s):  
C. Sivaram
Keyword(s):  
Cosmological Model ◽  
Early Universe ◽  
Hubble Constant ◽  
Matter Density ◽  
Inflationary Universe ◽  
Expansion Phase ◽  
Exponential Expansion ◽  
The Universe ◽  
Inflationary Models ◽  
Universe Models

Recently it has been shown that many of the puzzling features of conventional cosmological models (such as the horizon and flatness problems) could be explained by invoking inflationary models of the early universe with an exponential expansion phase at very early epochs. These models have the added advantage that they are able to make a definite prediction about the present matter density in the universe, i.e. they require that the density be exactly equal to the closure density which in turn can be easily estimated from the Hubble constant now known to within a factor of two. Now if one goes back to an earlier idea that explored the possibility of unusual clustering of quasar redshifts around z = 2 or 3, we get an example of another cosmological model with a definite prediction for the present overall matter density. This is a modified version of the Eddington-Lemaitre type of model which naturally accommodates such features as a clustering of quasars at certain epochs. From these models one can get a prediction for the present matter density which would be an involved function of the Hubble constant and the redshifts at which such clustering occurs. It can be shown that if such clustering had occurred at any z, the present matter density predicted would be substantially smaller than the corresponding closure density. The conclusion is that any clustering of quasar redshifts is incompatiable with inflationary universe models, indirectly providing observational support for these new theories.

scholarly journals Angular velocity of rotation of extended bodies in general relativity

1996 ◽  
Vol 172 ◽  
pp. 309-320
Author(s):  
S.A. Klioner
Keyword(s):  
General Relativity ◽  
Angular Velocity ◽  
Rigid Body ◽  
Rotational Motion ◽  
The Body ◽  
Astronomical Observations ◽  
Newtonian Approximation ◽  
Accurate Definition ◽  
Principal Axes ◽  
Definition Of

We consider rotational motion of an arbitrarily composed and shaped, deformable weakly self-gravitating body being a member of a system of N arbitrarily composed and shaped, deformable weakly self-gravitating bodies in the post-Newtonian approximation of general relativity. Considering importance of the notion of angular velocity of the body (Earth, pulsar) for adequate modelling of modern astronomical observations, we are aimed at introducing a post-Newtonian-accurate definition of angular velocity. Not attempting to introduce a relativistic notion of rigid body (which is well known to be ill-defined even at the first post-Newtonian approximation) we consider bodies to be deformable and introduce the post-Newtonian generalizations of the Tisserand axes and the principal axes of inertia.

THE GEOMETRY OF THE TORUS UNIVERSE

2007 ◽  
Vol 16 (04) ◽  
pp. 681-686 ◽  
Author(s):  
R. MURDZEK
Keyword(s):  
General Relativity ◽  
Riemannian Metric ◽  
Cyclic Universe ◽  
Universe Models

In this contribution, we show that the cyclic universe models naturally emerge from torus geometry in a braneworld scenario. The Riemannian metric on torus and the fundamental tensors of the General Relativity are derived. A discussion on particular aspects of this model is also given.

scholarly journals Relativity in Modern Astrometry and Celestial Mechanics — An Overview

2000 ◽  
Vol 180 ◽  
pp. 264-274 ◽  
Author(s):  
S. Klioner
Keyword(s):  
General Relativity ◽  
Celestial Mechanics ◽  
Relativistic Effects ◽  
Short Introduction ◽  
Astronomical Observations

AbstractAfter a short introduction into experimental foundations of general relativity, an overview of modern relativistic modelling of astronomical observations is given. The principal relativistic effects in various kind of observations are reviewed, and the problems for increasing accuracy of the astrometric catalogs due to general relativity are formulated.

Geological Time Versus Astronomical Time: Are Scientific Theories Falsifiable?

1989 ◽  
Vol 8 (2) ◽  
pp. 167-169 ◽  
Author(s):  
Norriss Hetherington
Keyword(s):  
General Relativity ◽  
Homogeneous Model ◽  
Scientific Theories ◽  
Geological Time ◽  
Astronomical Observations ◽  
The Earth ◽  
Geological Age ◽  
Astronomical Time ◽  
Edwin Hubble ◽  
The Universe

During the 1930s when a relativistic, expanding, homogeneous model of the universe lead to an age for the universe embarrassingly less than the geological age of the earth, the astronomer Edwin Hubble, influenced by philosophical values, persisted in his support for a theory in conflict with observation and prediction. Notwithstanding well attested and unrefutable evidence of geological time, and various astronomical observations as well, the theory of a homogeneous, expanding universe of general relativity proved, in practice, not falsifiable.

Sign in / Sign up

Export Citation Format

Share Document