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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
01 Aug 2002-Pramana
TL;DR: In this article, the authors present evidence for a nonsingular origin of the universe with intial conditions determined by quantum physics and relativistic gravity in particular the present temperature of the microwave background and the present density of the Universe.
Abstract: We present evidence for a nonsingular origin of the Universe with intial conditions determined by quantum physics and relativistic gravity In particular, we establish that the present temperature of the microwave background and the present density of the Universe agree well with our predictions from these intial conditions, after evolution to the present age using the Einstein-Friedmann equation Remarkably, the quantum origin for the Universe naturally allows its evolution at exactly the critical density We also discuss the consequences of these results to some fundamental aspects of quantum physics in the early Universe

3 citations

Journal ArticleDOI
TL;DR: The decelerating Einstein de Sitter (EdS) universe as mentioned in this paper is an alternative to the accelerating ΛCDM universe, in which dark energy is a different phase of dark matter located only in intergalactic space (IGS), and it has an index of refraction n ≥ 1.50, and hence a reduced speed of light c / n through it.
Abstract: This work briefly reviews and extends the author’s three previous works (2015), Journal of Modern Physics, 6, 78-87, and 1360-1370; (2016), 7, 1829-1844 that propose as an alternative to the accelerating ΛCDM universe, the decelerating Einstein de Sitter (EdS) universe, in which dark energy is a different phase of dark matter located only in intergalactic space (IGS), and that instead of a negative pressure, it has an index of refraction n≈1.50, and hence a reduced speed of light c / n through it. This allows the EdS universe to expand the extra distance necessary to obtain the diminished brightness of the Type Ia supernovae. In view of the recent suggestion that the universe is not accelerating, but possibly expanding uniformly, a table is given comparing both the accelerating and uniformly expanding universes with the EdS universe supplemented by the reduced speed of light. It is shown that fitting the uniformly expanding universe leads to a smaller value of n, and hence too short an age for the EdS universe, unlike the case with fitting the accelerating universe. The main result is that the proposed reduced speed of light in the IGS predicts discordant redshifts. It is shown that the current explanation of “accidental superposition,” is most likely insufficient to explain the number of observations, and that the present proposal could make up the difference. It can be tested astronomically, as illustrated in a figure.

3 citations

Journal ArticleDOI
TL;DR: In this article, the authors proposed a holographic energy model in which the energy coming from spatial curvature, matter and radiation can be obtained by using the particle horizon for the infrared cut-off.
Abstract: We suggest a holographic energy model in which the energy coming from spatial curvature, matter and radiation can be obtained by using the particle horizon for the infrared cut-off. We show the consistency between the holographic dark-energy model and the holographic energy model proposed in this paper. Then, we give a holographic description of the universe.

3 citations

Journal ArticleDOI
TL;DR: In this article, the optical depths of a radiation-dominated universe were derived for photoionization, Compton scattering, photon-matter pair production, photon photon scattering, and photon-photon pair production in interactions with the cosmic thermal background and baryonic matter.
Abstract: If the universe were radiation-dominated at redshifts greater than about 100-1000, eg, due to the presence of a small fraction of light particles in the dark matter, it would be optically thin in soft gamma-rays up to redshifts of 10,000 This is larger by an order of magnitude than for the matter-dominated universe X-rays and gamma-rays produced by cosmological high-energy processes are thus potentially observable up to z of about 10,000 Analytical formulas are derived for the optical depths of radiation-dominated universe due to photoionization, Compton scattering, photon-matter pair production, photon-photon scattering, and photon-photon pair production, in interactions with the cosmic thermal background and baryonic matter 29 refs

3 citations

Journal ArticleDOI
TL;DR: In this paper, it was shown that a five-dimensional Einstein-Yang-Mills theory defined in a flat Friedmann-Robertson-Walker universe compactified on a circle possesses degenerate vacua in four dimensions.

3 citations


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