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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 article, the motion of an observer in an isotropic universe may be determined by measurements, yielding a simple resolution to the twins paradox of relativity theory in such a universe.
Abstract: This paper considers how the motion of an observer in an isotropic universe may be determined by measurements. This provides a means to identify inertial frames, yielding a simple resolution to the twins paradox of relativity theory in such a universe. We propose that isotropy is a requirement for a frame to be inertial; this makes it possible to relate motion to the large scale structure of the universe.
9 citations
17 Mar 2004
TL;DR: In this paper, the shape of the primordial spectrum is very similar to that predicted by generic inflation models, and the angular scale at which the first acoustic peak appears is consistent with the flat universe predicted by inflation.
Abstract: Cosmologists have developed a phenomenally successful picture of structure in the universe based on the idea that the universe expanded exponentially in its earliest moments. There are three pieces of evidence for this exponential expansion--inflation--from observations of anisotropies in the cosmic microwave background. First, the shape of the primordial spectrum is very similar to that predicted by generic inflation models. Second, the angular scale at which the first acoustic peak appears is consistent with the flat universe predicted by inflation. Here the author describes the third piece of evidence, perhaps the most convincing of all: the phase coherence needed to account for the clear peak/trough structure observed by the WMAP satellite and its predecessors. The author also discusses alternatives to inflation that have been proposed recently and explain how they produce coherent phases.
9 citations
CERN1
TL;DR: In this paper, the authors constructed the quantum cosmology of an anistropic universe according to the "no-boundary" prescription of Hartle and Hawking, and showed it also implies that a large universe such as ours, is isotropic.
9 citations
TL;DR: In this paper, the authors studied cosmological perturbations in the context of an interacting dark energy model, where the holographic dark energy with IR cutoff decays into the cold dark matter (CDM), and introduced three IR cutoffs of Hubble horizon, particle horizon, and future event horizon.
Abstract: We study cosmological perturbations in the context of an interacting dark energy model, where the holographic dark energy with IR cutoff decays into the cold dark matter (CDM). For this purpose, we introduce three IR cutoffs of Hubble horizon, particle horizon, and future event horizon. Here we present small perturbations under the case that effective equation of state (EOS: ωeff) for the holographic energy density is determined to be the same negative constant as that for the CDM. Such new matter productions tend to dilute the density perturbations of CDM (matter contrast). For a decelerating universe of ωeff > -1/3, the matter contrast is growing as the universe evolves, while for an accelerating universe of ωeff < -1/3, the matter contrast is decaying, irrespective of the choice of IR cutoff. This shows clearly that the acceleration suppresses the growing of the density perturbations at the early universe.
9 citations
TL;DR: The cosmological equations for the general scalar tensor theory proposed by Nordvedt (1970) in a Bianchi type-I radiation-filled universe are solved and the behaviour of the model is discussed in this paper.
Abstract: The cosmological equations for the general scalar tensor theory proposed by Nordvedt (1970) in a Bianchi type-I radiation-filled Universe are solved and the behaviour of the model is discussed. There are two distinct situations. Either the Universe will explode from a bit band type singularity and continuously increase, or the Universe may continuously contract to approach the singularity at the end.
9 citations