Study Of Accelerated Cosmic Expansion
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Study Of Accelerated Cosmic Expansion
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Author : Nisha Rani
language : en
Publisher: Mohd Abdul Sattar
Release Date : 2022-08-09
Study Of Accelerated Cosmic Expansion written by Nisha Rani and has been published by Mohd Abdul Sattar this book supported file pdf, txt, epub, kindle and other format this book has been release on 2022-08-09 with Science categories.
Physical cosmology includes the scientific study of the origin, evolution and dynamics of the universe. Due to impressive progress both on the theoretical and observational side, scientists are able to resolve many of the puzzles of the universe. Nevertheless, many questions are not answered completely. For instance, "What are the constituents of the universe?" and "How does the dynamics of the universe evolve?" The curiosity to get convincing answers to these questions, motivates one to work in this field. According to the hot Big Bang model, the universe started from a bang and its properties change with time. The discovery of the Cosmic Microwave Background Radiation (CMBR) by Penzias and Wilson in 1965 was important in making the Big Bang model the accepted model of the universe [5]. A landmark discovery in 1998 by two groups working independently on Supernovae Ia was instrumental in changing the way we understand our universe. They found that the expansion of the universe is accelerating [6, 7]. To explain the accelerated expansion of the universe, various models have been proposed. The most widely accepted one is the Lambda Cold Dark Matter (ΛCDM) model [8]. According to this model, the universe is flat and is expanding at an accelerated rate. It is composed of baryonic matter, dark matter and dark energy. Dark energy is the name given to the cause of the cosmic acceleration.
Accelerated Cosmic Expansion
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Author : Claudia Moreno González
language : en
Publisher: Springer Science & Business Media
Release Date : 2013-11-29
Accelerated Cosmic Expansion written by Claudia Moreno González and has been published by Springer Science & Business Media this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013-11-29 with Science categories.
Proceedings from the 2012 Fourth International Meeting on Gravitation and Cosmology, focusing on accelerated cosmic expansion This volume provides both an update and a review of the state of alternative theories of gravity in connection with the accelerated expansion of the universe issue. Different theoretical proposals exist to explain the acceleration in the cosmic expansion, generating the dark energy issue and opening the possibility to theories of gravity alternative to general relativity. Related issues such as the dark matter problem are also surveyed in order to give the readers profound insight on the subject from different points of view. Comprised of short talks and plenary lectures given by leading experts in the field, some of them with brilliant and historic contributions, the book allows the reader to find readable and referenced surveys in topics like f(R) theories, the dark matter and dark energy issues, Modified Newtonian Dynamics (MOND) scenarios, f(T) theories, scalar-tensor theories derived from non-Riemannian geometries, emergent universes, the cosmological constant and other topics of current interest for younger and senior physicists and graduate students. These proceedings are from the Fourth International Meeting on Gravitation and Cosmology, held in Guadalajara, Jalisco, México, from 20 - 25 May, 2012, was sponsored by ICTP- Trieste, Italy and COECyTJAL-Universidad de Guadalajara, México. This event is a series of scientific meetings started in 2004 in Cuba, focusing on current and selected topics in the fields of gravitation and cosmology.
Accelerating Expansion
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Author : Gordon Belot
language : en
Publisher: Oxford University Press
Release Date : 2023-08-24
Accelerating Expansion written by Gordon Belot and has been published by Oxford University Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2023-08-24 with Mathematics categories.
Accelerating Expansion explores some of the philosophical implications of modern cosmology, focused on the significance that the discovery of the accelerating expansion of the Universe has for our understanding of time, geometry, and physics. The appearance of the cosmological constant in the equations of general relativity allows one to model universes in which space has an inherent tendency towards expansion. This constant, introduced by Einstein but subsequently abandoned by him, returned to centre stage with the discovery of the accelerating expansion. This pedagogically-oriented essay begins with a study of the most basic and elegant relativistic world that involves a positive cosmological constant, de Sitter spacetime. It then turns to the relatives of de Sitter spacetime that dominate modern relativistic cosmology. Some of the topics considered include: the nature of time and simultaneity in de Sitter worlds; the sense in which de Sitter spacetime is a powerful dynamical attractor; the limited extent to which observation can give us information about the topology of space in a world undergoing accelerated expansion; and cosmologists' favourite sceptical worry about the reliability of evidence and the possibility of knowledge, the problem of Boltzmann brains.
Lectures On Cosmology
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Author : Georg Wolschin
language : en
Publisher: Springer
Release Date : 2010-10-22
Lectures On Cosmology written by Georg Wolschin and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 2010-10-22 with Science categories.
The lectures that four authors present in this volume investigate core topics related to the accelerated expansion of the Universe. Accelerated expansion occured in the ?36 very early Universe – an exponential expansion in the in ationary period 10 s after the Big Bang. This well-established theoretical concept had rst been p- posed in 1980 by Alan Guth to account for the homogeneity and isotropy of the observable universe, and simultaneously by Alexei Starobinski, and has since then been developed by many authors in great theoretical detail. An accelerated expansion of the late Universe at redshifts z
Lectures On Cosmology
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Author : Georg Wolschin
language : en
Publisher: Springer
Release Date : 2010-03-10
Lectures On Cosmology written by Georg Wolschin and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 2010-03-10 with Science categories.
The lectures that four authors present in this volume investigate core topics related to the accelerated expansion of the Universe. Accelerated expansion occured in the ?36 very early Universe – an exponential expansion in the in ationary period 10 s after the Big Bang. This well-established theoretical concept had rst been p- posed in 1980 by Alan Guth to account for the homogeneity and isotropy of the observable universe, and simultaneously by Alexei Starobinski, and has since then been developed by many authors in great theoretical detail. An accelerated expansion of the late Universe at redshifts z
Cosmic Acceleration
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Author : Nishant Agarwal
language : en
Publisher:
Release Date : 2011
Cosmic Acceleration written by Nishant Agarwal and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with categories.
Our Universe has an exciting history of accelerated expansion. Following its inception in an event known as the big bang, the Universe underwent a phase of exponential expansion called inflation. Although precise observations of the cosmic microwave background (CMB) radiation and large-scale structure support the inflationary paradigm, the absence of a firm physical mechanism for inflation has led to a plethora of theoretical embarkments attempting to understand its genesis. Inflation lasted only for a fraction of a second, but observations suggest that thirteen billion years after inflation, the Universe began accelerating once again. This acceleration, which continues till date, is attributed to a mysterious component, dubbed dark energy, that fills up our Universe and accounts for almost 73% of the total energy density in the Universe. In this thesis we study and develop models of inflation and dark energy, in the light of current observations. We begin, in Chapter 1, with a detailed introduction to cosmic acceleration, and discuss various models of inflation and dark energy that have been studied in the literature in the recent years. In Chapter 2, we discuss how a hierarchy of Hubble flow parameters, extended to include the evolution of the inflationary sound speed, can be applied to compare a general, single-field inflationary action with cosmological observational data. In Chapter 3, we study the six-field dynamics of D3-brane inflation for a general scalar potential on the conifold, finding simple, universal behavior, such as a power law dependence for the probability of Ne e-folds of inflation. Subsequent chapters study modifications to the theory of gravity in an attempt to understand dark energy. In Chapter 4, we establish the dynamical attractor behavior in scalar-tensor theories of gravity, providing a powerful framework to analyze such theories, predicting common evolutionary characteristics that can be compared against cosmological constraints. Chapter 5 develops a cascading cosmology framework in order to study the cosmological implications of a sixdimensional (6D) theory of gravity. We find that cascading cosmology can indeed lead to an accelerating Universe. Finally, in Chapter 6, we study the issue of ghostlike instabilities in the cascading framework, and propose a mechanism to obtain flat brane and bulk solutions. We conclude in Chapter 7 with a discussion of the main results presented in this thesis.
Calculation Of The Cosmic Expansion Rate
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Author : Daniel Adamczyk
language : en
Publisher: Nick Rymer
Release Date : 2015-01-21
Calculation Of The Cosmic Expansion Rate written by Daniel Adamczyk and has been published by Nick Rymer this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015-01-21 with categories.
Scholarly Research paper from the year 2012 in the subject Physics - Astronomy, language: English, abstract: My idea for the accelerated expanding universe can not exist without the fourth spatial dimension of the Kaluza-Klein theory, not without a lot of strained balloon model and not without the power of a Big Bang explosion. One idea for the dark matter is a major component of it, because without it no accelerated expansion is possible. It would have made no sense to me to design a cosmological principle if I nad not found a way for the natural mass rejection and with which the Dark Energy at first is to explain. Crucial for the invention of this cosmological model is the speed of the enlargement of the balloon, which represents the dark matter as a relative increase in mass. The speed of movement, the velocity in fourth dimension, is by the character of the room in which we live, invisible. Unfortunately we will never be able to verify this view, since we are now living in the balloon skin. So the model is admittedly risky, because it requires many things which can never be put in appearances. Only circumstantial evidence can corroborate this view. It remembers to science of the structure of elementary particles. But even the summoning of this effort is not enough. In recognition of the Kaluza-Klein theory it would be necessary to put themselves in the situation of the inhabitants of this universe, to capture their mental perspective, and to prove so the view of this article. That's asking a lot, but the calculation reproduces the actual observation of the expansion rate very good. Probably we will never be in a better position to observe a universe. So I think a study of this view would be useful and necessary.
Studies Into The Nature Of Cosmic Acceleration
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Author : Jason Nicholas Dossett
language : en
Publisher:
Release Date : 2013
Studies Into The Nature Of Cosmic Acceleration written by Jason Nicholas Dossett and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013 with Cosmology categories.
Since its discovery more than a decade ago, the problem of cosmic acceleration has become one of the largest in cosmology and physics as a whole. An unknown dark energy component of the universe is often invoked to explain this observation. Mathematically, this works because inserting a cosmic fluid with a negative equation of state into Einstein's equations provides an accelerated expansion. There are, however, alternative explanations for the observed cosmic acceleration. Perhaps the most promising of the alternatives is that, on the very largest cosmological scales, general relativity needs to be extended or a new, modified gravity theory must be used. Indeed, many modified gravity models are not only able to replicate the observed accelerated expansion without dark energy, but are also more compatible with a unified theory of physics. Thus it is the goal of this dissertation to develop and study robust tests that will be able to distinguish between these alternative theories of gravity and the need for a dark energy component of the universe. We will study multiple approaches using the growth history of large-scale structure in the universe as a way to accomplish this task. These approaches include studying what is known as the growth index parameter, a parameter that describes the logarithmic growth rate of structure in the universe, which describes the rate of formation of clusters and superclusters of galaxies over the entire age of the universe. We will explore the effectiveness of this parameter to distinguish between general relativity and modifications to gravity physics given realistic expectations of results from future experiments. Next, we will explore the modified growth formalism wherein deviations from the growth expected in general relativity are parameterized via changes to the growth equations, i.e. the perturbed Einstein's equations. We will also explore the impact of spatial curvature on these tests. Finally, we will study how dark energy with some unusual properties will affect the conclusiveness of these tests.
The Accelerating Universe
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Author : Mario Livio
language : en
Publisher: Turner Publishing Company
Release Date : 2008-05-02
The Accelerating Universe written by Mario Livio and has been published by Turner Publishing Company this book supported file pdf, txt, epub, kindle and other format this book has been release on 2008-05-02 with Science categories.
Advance Praise for The Accelerating Universe "The Accelerating Universe is not only an informative book about modern cosmology. It is rich storytelling and, above all, a celebration of the human mind in its quest for beauty in all things." —Alan Lightman, author of Einstein's Dreams "This is a wonderfully lucid account of the extraordinary discoveries that have made the last years a golden period for observational cosmology. But Mario Livio has not only given the reader one clear explanation after another of what astronomers are up to, he has used them to construct a provocative argument for the importance of aesthetics in the development of science and for the inseparability of science, art, and culture." —Lee Smolin, author of The Life of the Cosmos "What a pleasure to read! An exciting, simple account of the universe revealed by modern astronomy. Beautifully written, clearly presented, informed by scientific and philosophical insights." —John Bahcall, Institute for Advanced Study "A book with charm, beauty, elegance, and importance. As authoritative a journey as can be taken through modern cosmology." —Allan Sandage, Observatories of the Carnegie Institution of Washington
Lecture Notes In Cosmology
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Author : Oliver Piattella
language : en
Publisher: Springer
Release Date : 2018-07-21
Lecture Notes In Cosmology written by Oliver Piattella and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018-07-21 with Science categories.
Cosmology has become a very active research field in the last decades thanks to the impressing improvement of our observational techniques which have led to landmark discoveries such as the accelerated expansion of the universe, and have put physicists in front of new mysteries to unveil, such as the quest after the nature of dark matter and dark energy. These notes offer an approach to cosmology, covering fundamental topics in the field: the expansion of the universe, the thermal history, the evolution of small cosmological perturbations and the anisotropies in the cosmic microwave background radiation. Some extra topics are presented in the penultimate chapter and some standard results of physics and mathematics are available in the last chapter in order to provide a self-contained treatment. These notes offer an in-depth account of the above-mentioned topics and are aimed to graduate students who want to build an expertise in cosmology.