Download or read book Studies Into the Nature of Cosmic Acceleration written by Jason Nicholas Dossett and published by . This book was released on 2013 with total page 536 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Connecting Quarks with the Cosmos written by National Research Council and published by National Academies Press. This book was released on 2003-03-12 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advances made by physicists in understanding matter, space, and time and by astronomers in understanding the universe as a whole have closely intertwined the question being asked about the universe at its two extremesâ€"the very large and the very small. This report identifies 11 key questions that have a good chance to be answered in the next decade. It urges that a new research strategy be created that brings to bear the techniques of both astronomy and sub-atomic physics in a cross-disciplinary way to address these questions. The report presents seven recommendations to facilitate the necessary research and development coordination. These recommendations identify key priorities for future scientific projects critical for realizing these scientific opportunities.
Download or read book Expansion of the Universe written by Steff Jaywan and published by Dedona Publishing. This book was released on with total page 43 pages. Available in PDF, EPUB and Kindle. Book excerpt: The universe is a vast and enigmatic expanse, filled with countless mysteries that have intrigued scientists and philosophers for centuries. One of the most profound discoveries of modern cosmology is that the universe is not only expanding but doing so at an accelerating rate. This revelation has reshaped our understanding of the cosmos and introduced the concept of dark energy as a dominant force driving this acceleration. In this book, we embark on a journey through the history of cosmological thought, from the early observations that hinted at an expanding universe to the groundbreaking discoveries that revealed its acceleration. We will explore the role of the cosmological constant, a term introduced by Einstein in his equations of General Relativity, which has come to be associated with dark energy. We begin with a foundational understanding of the universe's expansion, delving into the Big Bang theory and the key observations that support it. From there, we examine the pivotal role of the cosmological constant and its implications for the structure and fate of the universe. As we navigate through the complexities of dark energy and its various theoretical models, we will also address the challenges and alternative theories that scientists are exploring to explain this cosmic acceleration. Finally, we will consider the future of cosmological research, highlighting the ongoing quests to unravel the mysteries that still elude us.
Download or read book New Worlds New Horizons in Astronomy and Astrophysics written by National Research Council and published by National Academies Press. This book was released on 2011-02-04 with total page 324 pages. Available in PDF, EPUB and Kindle. Book excerpt: Driven by discoveries, and enabled by leaps in technology and imagination, our understanding of the universe has changed dramatically during the course of the last few decades. The fields of astronomy and astrophysics are making new connections to physics, chemistry, biology, and computer science. Based on a broad and comprehensive survey of scientific opportunities, infrastructure, and organization in a national and international context, New Worlds, New Horizons in Astronomy and Astrophysics outlines a plan for ground- and space- based astronomy and astrophysics for the decade of the 2010's. Realizing these scientific opportunities is contingent upon maintaining and strengthening the foundations of the research enterprise including technological development, theory, computation and data handling, laboratory experiments, and human resources. New Worlds, New Horizons in Astronomy and Astrophysics proposes enhancing innovative but moderate-cost programs in space and on the ground that will enable the community to respond rapidly and flexibly to new scientific discoveries. The book recommends beginning construction on survey telescopes in space and on the ground to investigate the nature of dark energy, as well as the next generation of large ground-based giant optical telescopes and a new class of space-based gravitational observatory to observe the merging of distant black holes and precisely test theories of gravity. New Worlds, New Horizons in Astronomy and Astrophysics recommends a balanced and executable program that will support research surrounding the most profound questions about the cosmos. The discoveries ahead will facilitate the search for habitable planets, shed light on dark energy and dark matter, and aid our understanding of the history of the universe and how the earliest stars and galaxies formed. The book is a useful resource for agencies supporting the field of astronomy and astrophysics, the Congressional committees with jurisdiction over those agencies, the scientific community, and the public.
Download or read book The Accelerating Universe written by Mario Livio and published by Turner Publishing Company. This book was released on 2008-05-02 with total page 282 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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
Download or read book Space Physics Strategy implementation Study written by and published by . This book was released on 1991 with total page 282 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Cosmic Acceleration written by Nishant Agarwal and published by . This book was released on 2011 with total page 292 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Nuclear Science Abstracts written by and published by . This book was released on 1976-02 with total page 722 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Particle Acceleration in Cosmic Plasmas written by André Balogh and published by Springer. This book was released on 2015-06-25 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The review articles collected in this volume present a critical assessment of particle acceleration mechanisms and observations from suprathermal particles in the magnetosphere and heliosphere to high-energy cosmic rays, thus covering a range of energies over seventeen orders of magnitude, from 103 eV to 1020 eV. The main themes are observations of accelerated populations from the magnetosphere to extragalactic scales and assessments of the physical processes underlying particle acceleration in different environments (magnetospheres, the solar atmosphere, the heliosphere, supernova remnants, pulsar wind nebulae and relativistic outflows). Several contributions review the status of shock acceleration in different environments and also the role of turbulence in particle acceleration. Observational results are compared with modelling in different parameter regimes. The book concludes with contributions on the status of particle acceleration research and its future perspectives. This volume is aimed at graduate students and researchers active in astrophysics and space science. Previously published in Space Science Reviews journal, Vol. 173 Nos. 1-4, 2012.
Download or read book Energy Budget In The High Energy Universe Proceedings Of The International Workshop written by Katsuhiko Sato and published by World Scientific. This book was released on 2007-03-06 with total page 413 pages. Available in PDF, EPUB and Kindle. Book excerpt: The existence of materials with very high specific energies greatly exceeding the local virial temperature is best represented by cosmic rays, whose origin has long been a mystery. Recent astrophysical observations in X-ray, gamma-ray, neutrino, and high energy cosmic ray experiments, in conjunction with theoretical studies, have revealed various new aspects of the high energy universe, including promising candidates for cosmic ray acceleration sites. As each approach has its own advantages and limitations, it is expected that joint efforts by experimentalists and theorists in various related fields are essential.The contributions in this volume include observation of the universe through a wide range of techniques for detecting cosmic rays, neutrinos, X-rays and gamma-rays, as well as theoretical considerations in understanding their nature and astrophysical aspects.
Download or read book On the Wave Nature of Matter written by Donald C. Chang and published by Springer Nature. This book was released on with total page 341 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book High Energy Astrophysics written by Malcolm S. Longair and published by Cambridge University Press. This book was released on 2011-02-03 with total page 885 pages. Available in PDF, EPUB and Kindle. Book excerpt: Providing students with an in-depth account of the astrophysics of high energy phenomena in the Universe, the third edition of this well-established textbook is ideal for advanced undergraduate and beginning graduate courses in high energy astrophysics. Building on the concepts and techniques taught in standard undergraduate courses, this textbook provides the astronomical and astrophysical background for students to explore more advanced topics. Special emphasis is given to the underlying physical principles of high energy astrophysics, helping students understand the essential physics. The third edition has been completely rewritten, consolidating the previous editions into one volume. It covers the most recent discoveries in areas such as gamma-ray bursts, ultra-high energy cosmic rays and ultra-high energy gamma rays. The topics have been rearranged and streamlined to make them more applicable to a wide range of different astrophysical problems.
Download or read book Cosmic Acceleration as Quantum Gravity Phenomenology written by Chanda Rosalyn Sojourner Prescod-Weinstein and published by . This book was released on 2010 with total page 129 pages. Available in PDF, EPUB and Kindle. Book excerpt: The discovery of cosmic acceleration has prompted the need for a new understanding of cosmology. The presence of this acceleration is often described as the dark energy problem or the Lambda problem. The simplest explanation is that the acceleration is due to addition of a cosmological constant to Einstein's equation, but this resolution is unsatisfactory as it leaves several unanswered questions. Although General Relativity has been tested in the strong-field limit, the apparent dark energy may be urging us to consider experimental cosmology as such a test for large scales. In this vein, I have pursued a study of modifications to Einstein's gravity as well as possible related quantum gravity phenomenology. Not only must the details of modified gravities be worked out, but their impact on other astrophysics must be checked. For example, structure formation provides a strong test of any cosmic acceleration model because a successful dark energy model must not inhibit the development of observed large-scale structures. Traditional approaches to studies of structure formation in the presence of dark energy or a modified gravity implement the Press & Schechter formalism. I explore the potential for universality in the Press & Schechter formalism and what dark matter haloes may be able to tell us about cosmology.
Download or read book Flat Space Cosmology written by Eugene Terry Tatum and published by Universal-Publishers. This book was released on 2021-06-15 with total page 204 pages. Available in PDF, EPUB and Kindle. Book excerpt: This compilation based upon recent peer-reviewed journal publications encapsulates how the Flat Space Cosmology model (FSC) has become the primary competitor to the inflationary standard model of cosmology. New ideas concerning black holes, dark energy and dark matter are presented and shown to correlate extremely well with astronomical observations. Anyone who follows the fast-changing science of cosmology, has an interest in the latest developments, and would like to know how it is that our universe appears to follow equations one would ordinarily expect for a time-reversed black hole (!), may find this book to be fascinating. Cosmology is the study of how the universe has changed over the great span of time (roughly 14 billion years). Later centuries will look back upon the period from 1990-2030 as a ‘Golden Age’ of theoretical and observational cosmology. It is highly likely that we are on the verge of a deeper understanding of the most mysterious energy (‘dark energy’) and matter (‘dark matter’) comprising the majority of energy and matter in the universe. Some of the material presented in this book is on the cutting edge of dark energy and dark matter theoretical work. This book summarizes, for the first time, the groundbreaking publications of two cosmologists, one from the United States and the other from India, from 2015 thru 2020. During this highly productive period, the authors stealthily published their papers in six different peer-reviewed scientific journals, so that the model could be quietly explored in all aspects before bringing it all together in a single book. This is that book!
Download or read book The Extravagant Universe written by Robert P. Kirshner and published by Princeton University Press. This book was released on 2016-09-13 with total page 313 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Extravagant Universe tells the story of a remarkable adventure of scientific discovery. One of the world's leading astronomers, Robert Kirshner, takes readers inside a lively research team on the quest that led them to an extraordinary cosmological discovery: the expansion of the universe is accelerating under the influence of a dark energy that makes space itself expand. In addition to sharing the story of this exciting discovery, Kirshner also brings the science up-to-date in a new epilogue. He explains how the idea of an accelerating universe--once a daring interpretation of sketchy data--is now the standard assumption in cosmology today. This measurement of dark energy--a quality of space itself that causes cosmic acceleration--points to a gaping hole in our understanding of fundamental physics. In 1917, Einstein proposed the "cosmological constant" to explain a static universe. When observations proved that the universe was expanding, he cast this early form of dark energy aside. But recent observations described first-hand in this book show that the cosmological constant--or something just like it--dominates the universe's mass and energy budget and determines its fate and shape. Warned by Einstein's blunder, and contradicted by the initial results of a competing research team, Kirshner and his colleagues were reluctant to accept their own result. But, convinced by evidence built on their hard-earned understanding of exploding stars, they announced their conclusion that the universe is accelerating in February 1998. Other lines of inquiry and parallel supernova research now support a new synthesis of a cosmos dominated by dark energy but also containing several forms of dark matter. We live in an extravagant universe with a surprising number of essential ingredients: the real universe we measure is not the simplest one we could imagine.
Download or read book Physics Martinus Cosmology and the Theory of Everything written by Leif Pettersson and published by BalboaPress. This book was released on 2012-03-22 with total page 140 pages. Available in PDF, EPUB and Kindle. Book excerpt: A completely New Understanding of Reality! Presenting FET, a new model that meets physicists' criteria for what they term The Theory of Everything and provides answers to many unsolved mysteries of physics. FET describes the qualitative vacuum energies, the Fundamental Energies in the zero-point filed underlying and constituting the entire physical world, explaining dark matter, dark energy, particles, mass, Higgs field, gravity, space-time and much more. Leif Pettersson has succeeded in presenting this complex, astounding material in a clear-cut, rational and comprehensive way. The subject is highly topical and of great public interest it connects to the research at CERN and it also matches the presentation of science and popular science in today's media. The book is richly illustrated in color. Physicists have worked intensively for a long time to understand our physical world. They have also been struggling to unify the four forces of nature: gravity, electromagnetism and the strong and weak nuclear forces into a Theory of Everything, but so far without success. In this book Leif Pettersson presents a groundbreaking and very exciting material with theories based on the intuitive knowledge contained in Martinus Cosmology. These theories demonstrate a new model, The Fundamental Energy Theory FET, that without any contradiction unifies the four fundamental forces of nature, and in fact gives us The Theory of Everything! Hypotheses are presented that may explain the mechanisms behind Einsteins General and Special Theories of Relativity, quantum physics with its hypothetical gravitons, Higgs particles etc. and the enigmatic dark matter, dark energy and a lot more. The Fundamental Energy Theory offers a logical, coherent key to many of the unsolved mysteries of physics, e.g. those being currently studied in the worlds biggest research project so far, the particle accelerator in CERN. The book is made available by New Cosmic Paradigm (NCP), an independent organization representing and working with the branch of the intuitive knowledge contained in Martinus Cosmology that is building bridges to Science, focusing on the great issues about Life, Consciousness and Reality posed by humanity and science. This branch is especially represented by Per Bruus-Jensen, former trainee and collaborator with Martinus. Physics, Martinus Cosmolgy and The Theory of Everything The Fundamental Energy Theory FET by Leif Pettersson is an important addition to this field. More information at www.newcosmicparadigm.org Welcome!
Download or read book STUDY OF ACCELERATED COSMIC EXPANSION written by Nisha Rani and published by Mohd Abdul Sattar. This book was released on 2022-08-09 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
