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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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Journal ArticleDOI
TL;DR: A novel photometry-based estimation of the total number of stars in the Universe is presented, based on the energy conservation law and actual measurements of the extragalactic background light levels.
Abstract: A novel photometry-based estimation of the total number of stars in the Universe is presented. The estimation method is based on the energy conservation law and actual measurements of the extragalactic background light levels. By assuming that every radiated photon is kept within the Universe volume, i.e., by approximating the Universe as an integrating cavity without losses, the total number of stars in the Universe of about 6×1022 has been obtained.

7 citations

Journal ArticleDOI
TL;DR: In this paper, the authors studied the evolution of cosmological horizons in an accelerated universe with two state equations (cosmological constant and dust) and obtained closed-form expressions for the horizons.
Abstract: The particle and event horizons are widely known and studied concepts, but the study of their properties, in particular their evolution, have only been done so far considering a single state equation in a decelerating universe. This paper is the first of two where we study this problem from a general point of view. Specifically, this paper is devoted to the study of the evolution of these cosmological horizons in an accelerated universe with two state equations, cosmological constant and dust. We have obtained closed-form expressions for the horizons, which have allowed us to compute their velocities in terms of their respective recession velocities that generalize the previous results for one state equation only. With the equations of state considered, it is proved that both velocities remain always positive.

7 citations

Journal ArticleDOI
TL;DR: In this paper, it was shown graphically and analytically that spatially closed cosmological models can avoid recontraction of the Particle Horizon area if they expand fast enough.
Abstract: When Fischler and Susskind proposed a holographic prescription based on the Particle Horizon, they found that spatially closed cosmological models do not verify it due to the apparently unavoidable recontraction of the Particle Horizon area. In this article, after a short review of their original work, we expose graphically and analytically that spatially closed cosmological models can avoid this problem if they expand fast enough. It has been also shown that the Holographic Principle is saturated for a codimension one brane dominated Universe. The Fischler-Susskind prescription is used to obtain the maximum number of degrees of freedom per Planck volume at the Planck era compatible with the Holographic Principle.

7 citations

Journal ArticleDOI
31 Jan 2022-Symmetry
TL;DR: In this paper , it was shown that there could be a different universe outside the event horizon of our universe, which looks like a black hole for an outside observer, but incoming photons can enter and leave an imprint on our CMB sky.
Abstract: According to general relativity (GR), a universe with a cosmological constant Λ, like ours, is trapped inside an event horizon, r<3/Λ. What is outside? We show, using Israel (1967) junction conditions, that there could be a different universe outside. Our universe looks like a black hole for an outside observer. Outgoing radial null geodesics cannot escape our universe, but incoming photons can enter and leave an imprint on our CMB sky. We present a picture of such a fossil record from the analysis of CMB maps that agrees with the black hole universe predictions but challenges our understanding of the origin of the primordial universe.

7 citations

Journal ArticleDOI
TL;DR: In this article, a complex scalar model with particle-number-violating mass terms was introduced and the time evolution of the particle number density with nonequilibrium quantum field theory was studied.
Abstract: Particle-number-violating interactions wash out the primordial asymmetry of the particle number density generated by some interaction satisfying Sakharov conditions for baryogenesis In this paper, we study how the primordial asymmetry evolves in time under the presence of particle-number-violating interactions and in the environment of an expanding universe We introduce a complex scalar model with particle-number-violating mass terms and calculate the time evolution of the particle number density with nonequilibrium quantum field theory We show how the time evolution of the number density depends on parameters, including the chemical potential related to the particle number, temperature, the size of the particle-number-violating mass terms, and the expansion rate of the universe The number density behaves differently depending upon whether the chemical potential is larger or smaller than the rest mass of the scalar particle When the chemical potential is smaller than the mass, the interference among the contribution of oscillators with various momenta reduces the number density in addition to the dilution due to the expansion of the universe In the opposite case, the oscillation of the particle number density lasts for a long time and the cancellation due to the interference does not occur

7 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202320
202247
20216
202010
201910
201814