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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, a particular form of cosmological term Λ as Λ =, where R is a average scale factor of the universe and β is a constant, is considered.
Abstract: In this paper, we investigate variation law for cosmological constant in the background of anisotropic Banchi type I space-time. We consider a particular form of cosmological term Λ as Λ = , where R is a average scale factor of the universe and β is a constant. The model obtained approaches isotropy at late times. For β = 1 model represent static universe. Physical and kinematical behavior of the model has been discussed.
Posted ContentDOI
12 Dec 2022
TL;DR: In this article , a connection between horizon thermodynamics and cosmological equations for a de Sitter universe has been established by using Padmanabhan's holographic equipartition law, which is related to the origin of spacetime dynamics.
Abstract: Horizon thermodynamics is expected to be related to the effective energy based on the energy density calculated from the Friedmann equation for a Friedmann--Robertson--Walker (FRW) universe. In the present study, the effective energy and thermostatistical quantities on a cosmological horizon are examined to clarify the holographic-like connection between them, with a focus on a de Sitter universe. To this end, the Helmholtz free energy on the horizon is derived from horizon thermodynamics. The free energy is found to be equivalent to the effective energy calculated from the Friedmann equation. This consistency is interpreted as a kind of holographic-like connection. To examine this connection, Padmanabhan's holographic equipartition law, which is related to the origin of spacetime dynamics, is applied to a de Sitter universe. It is found that the law should lead to a holographic-like connection. The holographic-like connection is considered to be a bridge between thermostatistical quantities on the horizon and in the bulk. For example, cosmological equations for a flat FRW universe can be derived from horizon thermodynamics by accepting the connection as a viable scenario. In addition, a thermal entropy equivalent to the Bekenstein--Hawking entropy is obtained from the Friedmann equation using the concept of a canonical ensemble in statistical physics. The present study provides new insight into the discussion of horizon thermodynamics and cosmological equations.
Posted ContentDOI
31 Aug 2022
TL;DR: In this article , a relativistic model of the universe is proposed, in which the geometry describes a 4D version of the 2-sheeted hyperboloid that is isotropic, homogeneous in space at a given time and inhomogeneous in time.
Abstract: This paper proposes a relativistic model of the Universe in which the geometry describes a 4D version of the 2-sheeted hyperboloid that is isotropic, homogeneous in space at a given time and inhomogeneous in time. The radius of this metric is temporal as opposed to spatial. It predicts both a Universe and Anti-Universe moving in opposite directions of time undergoing an expansion phase, followed by a collapsing phase. Using only the current age of the Universe and transition redshift, it predicts the accelerated expansion and it is shown that its Hubble diagram fits currently available supernova and quasar data as well as predicting a Hubble constant $H_0\approx71.6km/s/Mpc$. The angular term of the metric describes time dilation caused by the relativistic kinematic precession effect known as Thomas Precession which can be interpreted as spin about the time dimension. The model also makes two novel predictions: that the early Universe should have structures older than expected due to an increased amount of proper time relative to coordinate time in that era and that the background Universe should appear brighter than current models predict.
01 Jan 2003
TL;DR: In this paper, the authors proposed a cosmological model of the Hot Big Bang theory with the inflationary hypothesis, in which the statistical properties of the image of the CMB allow them to measure most of the cosmologically parameters.
Abstract: Several experiments (including BOOMERanG, MAXIMA, DASI, VSA, CBI) have recently detected very low contrast structures in the Cosmic Microwave Background (CMB), the otherwise isotropic radiation coming from the early Universe. These structures have a contrast of the order of 25 ppm and a dominant angular size of one degree. In the current cosmological model, these structures result from acoustic oscillations of the primeval plasma within the horizon at recombination (z » 1100). In the framework of the Hot Big Bang theory with the inflationary hypothesis, the statistical properties of the image of the CMB allow us to measure most of the cosmological parameters.
Posted Content
TL;DR: In this article, the cosmological constant influence on cosmic microwave background (CMB) temperature due to moving linear cosmic strings was investigated. But the results were limited to the case of a linear cosmic string in an accelerated expanding universe.
Abstract: We want to find the cosmological constant influence on cosmic microwave background (CMB) temperature due to moving linear cosmic strings. Considering the space-time metric of a linear cosmic string in an accelerated expanding universe, the Gott-Kaiser-Stebbins (GKS) effect, as an important mechanism in producing temperature discontinuity in the CMB, is considered and its modification due to the effect of the cosmological constant is calculated. The result shows that a positive cosmological constant (i.e. the presence of cosmic strings in an accelerated expanding universe) weakens the discontinuity in temperature so that more strong resolution is needed to detect the corresponding influences on the CMB power spectrum and anisotropy.

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