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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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01 Jan 1986
TL;DR: The age of the oldest objects in the universe has been shown to be smaller than the age of space-time arena itself as discussed by the authors, which is not the case for the universe itself.
Abstract: The age of the oldest objects in the universe has obviously to be smaller than the age of the space-time arena itself.
TL;DR: The mean density of matter, as estimated from deep optical samples of galaxies, is too low to close the universe as mentioned in this paper, but some additional considerations do not exclude such a possibility.
Abstract: The mean density of matter, as estimated from deep optical samples of galaxies, is too low to close the Universe. However, some additional considerations do not exclude such a possibility.
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TL;DR: In this article, a cosmological model with variable speed of light (c), gravitational constant (G), and cosmology constant (Lambda) was proposed to solve the horizon, flatness and monopole problems of the early universe.
Abstract: We have investigated a cosmological model with variable speed of light (c), gravitational constant (G) and cosmological constant (Lambda). The model is shown to solve the horizon, flatness and monopole problems of the early universe. We have found that with a certain variation of these parameters the model predicts a cosmic acceleration. The model also predicts that for a flat universe Lambda vanishes in both radiation and matter phases. If the gravitational constant is allowed to increase then we might not need the existence of dark matter.
01 Nov 2009
TL;DR: In this article, the relation between the entanglement of a coarse-grained scalar field and the scale of the sound horizon was investigated, and it was shown that the distance between the two points exceeds the sound-horizon.
Abstract: Entanglement is the purely quantum correlation and does not exist in the classical mechanics. It is considered that the quantum fluctuations of a field which occur in the inflationary era become classical by the effect of the accelerated expansion, so their entanglement must disappear in this stage. We investigated the entanglement for a coarse-grained scalar field in 2 neighboring regions on the expanding spacetime [1]. As the result, it is indicated that the entanglement disappears when the distance between the 2 points exceeds the sound horizon. In this presentation, we discuss the relation between the entanglement of the field and the scale of sound horizon.
TL;DR: In this article, the cosmological parameters of the universe were estimated by joint analysis of the Cosmic Microwave Background, Supernovae Ia, peculiar velocities, cluster abundance and redshift surveys.
Abstract: Observational tests for the homogeneity of the Universe on large scales are reviewed. Assuming the Cosmological Principle we then estimate cosmological parameters by joint analysis of the Cosmic Microwave Background, Supernovae Ia, peculiar velocities, cluster abundance and redshift surveys. Our results are consistent with results obtained by other groups, suggesting a best-fit FRW Universe with $\omegam = 1 -\lambda \approx 0.3$ and $H_0 \approx 75$ km/sec/Mpc. We point out some potential problems with this currently popular model.