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Particle horizon
About: Particle horizon is a research topic. Over the lifetime, 2096 publications have been published within this topic receiving 69137 citations.
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TL;DR: In this paper, an exact solution which represents a charged black hole in a Kaluza-Klein universe in the five-dimensional Einstein-Maxwell theory was examined, where the horizon is a squashed three-sphere with a constant size.
Abstract: We examine an exact solution which represents a charged black hole in a Kaluza-Klein universe in the five-dimensional Einstein-Maxwell theory. The spacetime approaches to the five-dimensional Kasner solution that describes expanding three dimensions and shrinking an extra dimension in the far region. The metric is continuous but not smooth at the black hole horizon. There appears a mild curvature singularity that a free-fall observer can traverse the horizon. The horizon is a squashed three-sphere with a constant size, and the metric is approximately static near the horizon.
6 citations
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TL;DR: In this article, the authors describe the universe as a local, inhomogeneous spherical bubble embedded in a flat matter dominated FLRW universe and derive a nonperturbative expression for the deceleration parameter q that can possibly describe the acceleration of the universe without dark energy, due to the effects associated with very long wave length super-horizon inflationary perturbations.
Abstract: We describe the universe as a local, inhomogeneous spherical bubble embedded in a flat matter dominated FLRW universe. Generalized exact Friedmann equations describe the expansion of the universe and an early universe inflationary de Sitter solution is obtained. A non-perturbative expression for the deceleration parameter q is derived that can possibly describe the acceleration of the universe without dark energy, due to the effects associated with very long wave length super-horizon inflationary perturbations. The suggestion by Kolbe et al. [9] that long wave length super-horizon inflationary modes can affect a local observable through inhomogeneities is considered in the light of our exact inhomogeneous model.
6 citations
TL;DR: Considering Bianchi type of space-time, the authors presented the model Universe containing strange quark matter, which is expanding, anisotropic, with a sign of dark energy that help in accelerating the expansion of this universe.
Abstract: Considering Bianchi type
III space-time we present the model Universe containing strange quark matter
which is expanding, anisotropic, with a sign of dark energy that help in
accelerated expansion of this Universe. It is also seen that the model Universe
contains both particles and strings but ultimately will have fluid containing
particles only. This model which we consider here is acceptable in view of the
present observations of the Universe. Some physical and geometrical properties
are also discussed.
6 citations
TL;DR: In this paper, the creation of scalar particles in the Bianchi-type I anisotropic universe was studied, and it was shown that the creation occurs in accordance with the black-body law only in a 2-dimensional hyper-surface relating to the cosmic expansion, provided that we fix two arbitrary constants appearing in a general expression for the Feynman propagator in terms of a procedure similar to that in the isotropic case.
Abstract: Because of an importance of the particle creation (especially, its possible fulfilment of the black-body law with a definite temperature) in an early universe to various other cosmological problems, we study how the creation of scalar particles occurs in the Bianchi type I anisotropic universe adopted in our previous works on the quantized scalar field. It is shown that, as in a special isotropic case dealt with in recent papers, the creation may occur at the sacrifice of the requirement that the quantization procedure should reproduce the usual theory for a free field in the limit when the anisotropic universe changes into the Minkowski space-time. It is further shown that the creation occurs in accordance with the black-body law only in a 2-dimensional hyper-surface relating to the anisotropic cosmic expansion, provided that we fix two arbitrary constants appearing in a general expression for the Feynman propagator in terms of a procedure similar to that in the isotropic case. A speculation on the isotropization of our model-universe is also made from the standpoint of seeking the attainment of the thermal equilibrium in the whole universe.
6 citations
TL;DR: In this paper, it is shown that some time after the matter in the universe is diluted enough, at, the decelerating expansion shifts spontaneously to an accelerating one without a dark energy.
Abstract: Lorentz gauge theory of gravity was recently introduced. We study the homogeneous and isotropic universe of this theory. It is shown that some time after the matter in the universe is diluted enough, at , the decelerating expansion shifts spontaneously to an accelerating one without a dark energy. We discuss that Lorentz gauge theory puts no constraint on the total energy content of the universe at present time and therefore the magnitude of vacuum energy predicted by field theory is not contradictory anymore. It is demonstrated that in this theory the limit on the number of relativistic particles in the universe is much looser than in GR. An inflationary mechanism is discussed as well. We show that the theory, unlike GR, does not require the slow-roll or similar conditions to drive the inflation at the beginning of the universe.
6 citations