Particle horizon

About: Particle horizon is a research topic. Over the lifetime, 2096 publications have been published within this topic receiving 69137 citations.

The Big Bang quantum cosmology: The matter-energy production epoch

Abstract: The exactly solvable quantum model of the homogeneous, isotropic and closed universe in the matter-energy production epoch is considered. It is assumed that the universe is originally filled with a uniform scalar field and a perfect fluid which defines a reference frame. The stationary state spectrum and the wave functions of the quantum universe are calculated. In this model the matter-energy in the universe has a component in the form of a condensate of massive zero-momentum excitation quanta of oscillations of primordial scalar field. The mean value of the scale factor of the universe in a given state is connected with the mass of a condensate by a linear relation. The nucleation rate of the universe from the initial cosmological singularity point is calculated. It is demonstrated that the process of nucleation of the universe can have an exponential (explosive) nature. The evolution of the universe is described as transitions with non-zero probabilities between the states of the universe with different masses of a condensate.

constant bulk viscosity drive the accelerated expansion of the universe

Abstract: We test a cosmological model which the only component is a pressureless fluid with a constant bulk viscosity as an explanation for the present accelerated expansion of the universe. We classify all the possible scenarios for the universe predicted by the model according to their past, present and future evolution and we test its viability performing a Bayesian statistical analysis using the SCP "Union" data set (307 SNe Ia), imposing the second law of thermodynamics on the dimensionless constant bulk viscous coefficient ˜ � and comparing the predicted age of the universe by the model with the constraints coming from the oldest globular clusters. The best estimated values found for ˜

A relativistic view on large scale N-body simulations

Abstract: We discuss the relation between the output of Newtonian N-body simulations on scales that approach or exceed the particle horizon to the description of general relativity. At leading order, the Zeldovich approximation is correct on large scales, coinciding with the general relativistic result. At second order in the initial metric potential, the trajectories of particles deviate from the second order Newtonian result and hence the validity of second order Lagrangian perturbation theory initial conditions should be reassessed when used in very large simulations. We also advocate using the expression for the synchronous gauge density as a well behaved measure of density fluctuations on such scales.

The Multi-Bang Universe: The Never-Ending Realm of Galaxies

Abstract: A new cosmological model is proposed for the dynamics of the Universe and the formation and evolution of galaxies. It is shown that the matter of the Universe contracts and expands in cycles, and that galaxies in a particular cycle may have imprints from the previous cycle. It is proposed that RHIC’s liquid gets trapped in the cores of galaxies in the beginning of each cycle and is liberated throughout time and is, thus, the power engine of AGNs. It is also proposed that the large-scale structure is a permanent property of the Universe, and thus, it is not created. It is proposed that spiral galaxies and elliptical galaxies are formed by mergers of nucleon vortices (vorteons) at the time of the big squeeze and immediately afterwards and that the merging process, in general, lasts an extremely long time, of many billion years. The origin of quasars is explained and the evaporation rate of RHIC’s liquid is calculated. The large mass at the center of quasar PDS 456 is calculated and agrees in order of magnitude with that attributed to a supposed black hole. It is concluded that the Universe is eternal and that space should be infinite or almost.

Cosmic inflation and big bang interpreted as explosions

Abstract: It has become common understanding that the recession of galaxies and the corresponding redshift of light received from them can only be explained by an expansion of the space between them and us. In this paper, for the presently favored case of a universe without spatial curvature, it is shown that this interpretation is restricted to comoving coordinates. It is proven by construction that within the framework of general relativity other coordinates exist in relation to which these phenomena can be explained by a motion of the cosmic substrate across space, caused by an explosion like big bang or by inflation preceding an almost big bang. At the place of an observer, this motion occurs without any spatial expansion. It is shown that in these "explosion coordinates" the usual redshift comes about by a Doppler shift and a subsequent gravitational shift. Making use of this interpretation, it can easily be understood why in comoving coordinates light rays of short spatial extensions expand and thus constitute an exemption from the rule that small objects up to the size of the solar system or even galaxies do not participate in the expansion of the universe. It is also discussed how the two interpretations can be reconciled with each other.