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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 2007
TL;DR: In this article, the authors discuss the physics of the early universe and inflation, and its answers and unanswered questions, and introduce inflationary solution of the Big Bang problems, and discuss the models of inflation, global geometry of the universe with inflation and cosmological dynamics with a scalar field.
Abstract: This chapter discusses the physics of the early universe and inflation. The concise history of the early universe is devoted to the Big Bang, and its answered and unanswered questions. The chapter introduces inflationary solution of the Big Bang problems. The models of inflation, global geometry of the universe with inflation, and cosmological dynamics with a scalar field are also discussed. According to the inflationary scenario, the universe at early times, before the standard radiation-dominated phase began, expanded quasi-exponentially in a vacuum-like state without entropy or particles. Preheating after inflation can be treated with the quantum field theory (QFT). QFT of (p)reheating, or theory of particle creation from inflation field in an expanding universe is a process where quantum effects of particle creation is not small but a spectacular process where all the particles of universe are created from the rolling classical inflation. The chapter reviews the basics and new developments in the theory of different types of preheating and reheating, and discusses the outputs of (p)reheating for cosmology. Hybrid inflation is another very important class of inflationary models. Preheating in hybrid inflation that contains a symmetry breaking mechanism in the Higgs field sector has a very different character than in chaotic inflation.
4 citations
Posted Content•
TL;DR: In this article, the authors solved the equation of emergence proposed by Padmanabhan by assuming the Komar energy density as a function of the Hubble parameter, which describes the evolution of the universe, which proceeds toward a late accelerating epoch.
Abstract: According to the principle of emergence, the expansion of the universe can be explained as the emergence of space with the progress of cosmic time. We have analytically solved the equation of emergence proposed by Padmanabhan by assuming the Komar energy density $\rho+3P$ as a function of the Hubble parameter. The resulting model describes the evolution of the universe, which proceeds toward a late accelerating epoch. Model parameters have been extracted using the cosmological observational data. Horizon entropy evolution of the model has been studied. The model predicts a universe having a transition from a prior decelerated epoch to a late accelerated epoch and reasonably predicts the cosmological constant.
4 citations
01 Jan 2016
TL;DR: The universe open or closed the density of matter in the universe, but end up in harmful downloads as mentioned in this paper, where instead of enjoying a good book with a cup of tea in the afternoon, instead they are facing with some infectious bugs inside their laptop.
Abstract: Thank you for downloading is the universe open or closed the density of matter in the universe. Maybe you have knowledge that, people have look numerous times for their favorite novels like this is the universe open or closed the density of matter in the universe, but end up in harmful downloads. Rather than enjoying a good book with a cup of tea in the afternoon, instead they are facing with some infectious bugs inside their laptop.
4 citations
Posted Content•
TL;DR: In this article, some specific dynamical models of the cosmological term ''Lambda$'' have been selected for investigating the nature of dark energy, connecting the free parameters of the models with the cosmic matter and vacuum energy density parameters, it is shown that the models are equivalent.
Abstract: Keeping in mind the current picture of an accelerating and flat Universe, some specific dynamical models of the cosmological term $\Lambda$ have been selected for investigating the nature of dark energy. Connecting the free parameters of the models with the cosmic matter and vacuum energy density parameters, it is shown that the models are equivalent. Using the selected models, the present values of some of the physical parameters have been estimated, and a glimpse at the past decelerating universe has also been presented. It is observed that most of these cosmological parameters nicely agree with the values suggested by the Type Ia Supernovae and other experimental data.
4 citations
TL;DR: In this article, the authors studied the thermodynamic quantities like temperature of the universe, heat capacity and squared speed of sound in generalized gravity theories like Brans-Dicke, Ho$\check{\text r}$ava-Lifshitz and $f(R)$ gravities.
Abstract: In this work, we have studied the thermodynamic quantities like temperature of the universe, heat capacity and squared speed of sound in generalized gravity theories like Brans-Dicke, Ho$\check{\text r}$ava-Lifshitz and $f(R)$ gravities. We have considered the universe filled with dark matter and dark energy. Also we have considered the equation of state parameters for open, closed and flat models. We have observed that in all cases the equation of state behaves like quintessence. The temperature and heat capacity of the universe are found to decrease with the expansion of the universe in all cases. In Brans-Dicke and $f(R)$ gravity theories the squared speed of sound is found to exhibit increasing behavior for open, closed and flat models and in Ho$\check{\text r}$ava-Lifshitz gravity theory it is found to exhibit decreasing behavior for open and closed models with the evolution of the universe. However, for flat universe, the squared speed of sound remains constant in Ho$\check{\text r}$ava-Lifshitz gravity.
4 citations