Cosmology

2017 ◽  
Author(s):  
Nicholas Manton ◽  
Nicholas Mee
Keyword(s):  
Galaxy Formation ◽  
Large Scale ◽  
Cosmological Parameters ◽  
Big Bang ◽  
Newtonian Gravity ◽  
Microwave Background ◽  
Cosmological Redshift ◽  
Frw Model ◽  
The Big Bang ◽  
The Universe

This chapter is about the large-scale structure of the universe, how it is described in general relativity and recent advances in determining the cosmological parameters. The Hubble distance–redshift relationship is discussed. The assumptions of the FRW cosmologies are presented and the FRW solutions of Einstein equation are derived. The FRW model is interpreted in terms of Newtonian gravity. Cosmological redshift is explained. The evidence for dark matter and its possible origin are discussed. The evidence for the Big Bang is presented, including the cosmic microwave background and the latest measurements of the CMB by the Planck probe. The evidence for dark energy is discussed, along with its interpretation as an FRW cosmology with a non-zero cosmological constant. Computer models of galaxy formation are discussed. Outstanding cosmological puzzles are presented along with their possible solution by inflationary models.

scholarly journals Large Scale Anisotropy of the Cosmic Microwave Background

1974 ◽  
Vol 63 ◽  
pp. 157-162 ◽  
Author(s):  
R. B. Partridge
Keyword(s):  
Angular Distribution ◽  
Large Scale ◽  
Background Radiation ◽  
Big Bang ◽  
Microwave Background ◽  
Initial State ◽  
Microwave Background Radiation ◽  
Cosmological Data ◽  
The Big Bang ◽  
The Universe

It is now generally accepted that the microwave background radiation, discovered in 1965 (Penzias and Wilson, 1965; Dicke et al., 1965), is cosmological in origin. Measurements of the spectrum of the radiation, discussed earlier in this volume by Blair, are consistent with the idea that the radiation is in fact a relic of a hot, dense, initial state of the Universe – the Big Bang. If the radiation is cosmological, measurements of both its spectrum and its angular distribution are capable of providing important – and remarkably precise – cosmological data.

scholarly journals Of Cosmic Background Anisotropies

1996 ◽  
Vol 168 ◽  
pp. 31-44
Author(s):  
G.F. Smoot
Keyword(s):  
Large Scale ◽  
Thermal Emission ◽  
Big Bang ◽  
Microwave Background ◽  
The Standard Model ◽  
The Big Bang ◽  
The Universe ◽  
Fundamental Physical ◽  
Large Scale Structure Formation

Observations of the Cosmic Microwave Background (CMB) Radiation have put the standard model of cosmology, the Big Bang, on firm footing and provide tests of various ideas of large scale structure formation. CMB observations now let us test the role of gravity and General Relativity in cosmology including the geometry, topology, and dynamics of the Universe. Foreground galactic emissions, dust thermal emission and emission from energetic electrons, provide a serious limit to observations. Nevertheless, observations may determine if the evolution of the Universe can be understood from fundamental physical principles.

Linear Growth of Cosmological Perturbations

2013 ◽  
Author(s):  
Abraham Loeb ◽  
Steven R. Furlanetto
Keyword(s):  
Galaxy Formation ◽  
Big Bang ◽  
Density Fluctuations ◽  
Microwave Background ◽  
Cosmological Recombination ◽  
Small Density ◽  
Evolution Of Structure ◽  
First Galaxies ◽  
The Big Bang ◽  
The Universe

This chapter shows that, after cosmological recombination, the Universe had entered the “dark ages,” during which the relic cosmic microwave background (CMB) light from the Big Bang gradually faded away. During this “pregnancy” period (which lasted hundreds of millions of years), the seeds of small density fluctuations planted by inflation in the matter distribution grew until they eventually collapsed to make the first galaxies. In addition to the density evolution, the second key “initial condition” for galaxy formation is the temperature of the hydrogen and helium gas that had likewise collapsed into the first galaxies. Here, the chapter describes the first stages of these processes and introduces the methods conventionally used to describe the fluctuations. It follows the evolution of structure in the linear regime, when the perturbations are small.

scholarly journals ID 3 Evolution of Structure in the Universe

2009 ◽  
Vol 5 (H15) ◽  
pp. 45-45
Author(s):  
Simon D. M. White
Keyword(s):  
Dark Matter ◽  
Large Scale ◽  
Complex Structure ◽  
Big Bang ◽  
Microwave Background ◽  
Atomic Nuclei ◽  
High Quality Image ◽  
Present Universe ◽  
The Big Bang ◽  
The Universe

AbstractRecent studies of the Cosmic Microwave Background have provided us with a high quality image of the Universe when it was only 380,000 years old. At that time it was a near-uniform mixture of hydrogen, helium, dark matter and radiation, with no galaxies, no stars, no planets and no people, indeed no atomic nuclei heavier than Lithium. Under the action of gravity, the weak fluctuations observed in the microwave sky evolved into the extraordinarliy complex structure of our present Universe. I will show how supercomputer simulations can be used to demonstrate that such evolution does indeed reproduce the observed properties of today's galaxies and large-scale structures, thus confirming the extraordinary assumptions of the current structure formation paradigm. Only a quarter of the energy density of the present Universe is in gravitating matter; only a sixth of this matter is made of atoms or other known particles; only 5 percent of this baryonic material is currently inside galaxies. Most of today's Universe is in the form of Dark Energy; most of the gravitating matter is Dark Matter; and most of the baryons remain unseen in intergalactic space. The properties of the fluctuations measured in the microwave sky suggest that they originated very close to the Big Bang as quantum fluctuations of the vacuum itself. Everything has formed from nothing.

The Cosmic Microwave Background

2020 ◽  
pp. 272-289
Author(s):  
Hui Chieh Teoh
Keyword(s):  
Cosmic Microwave Background ◽  
Early Universe ◽  
Large Scale ◽  
Big Bang ◽  
Space Missions ◽  
Expanding Universe ◽  
Microwave Background ◽  
The Big Bang ◽  
The Universe

The cosmic microwave background (CMB) holds many secrets of the origin and the evolution of our universe. This ancient radiation was created shortly after the Big Bang, when the expanding universe cooled and became transparent, sending an afterglow of light in all directions. It is a pattern frozen in place that dates back to 375,000 years after the birth of the universe. Numerous experiments and space missions have made increasingly higher resolution maps of the CMB radiation, with the aims to learn more about the conditions of our early universe and the origin of stars, galaxies, and the large-scale cosmic structures that populate our universe today.

scholarly journals Relativistic Cosmology with an Introduction to Inflation

Universe ◽  
2021 ◽  
Vol 7 (8) ◽  
pp. 276
Author(s):  
Muhammad Zahid Mughal ◽  
Iftikhar Ahmad ◽  
Juan Luis García Guirao
Keyword(s):  
Standard Model ◽  
Early Universe ◽  
Large Scale ◽  
Initial Conditions ◽  
Big Bang ◽  
Relativistic Cosmology ◽  
The Standard Model ◽  
Big Bang Model ◽  
The Big Bang ◽  
The Universe

In this review article, the study of the development of relativistic cosmology and the introduction of inflation in it as an exponentially expanding early phase of the universe is carried out. We study the properties of the standard cosmological model developed in the framework of relativistic cosmology and the geometric structure of spacetime connected coherently with it. The geometric properties of space and spacetime ingrained into the standard model of cosmology are investigated in addition. The big bang model of the beginning of the universe is based on the standard model which succumbed to failure in explaining the flatness and the large-scale homogeneity of the universe as demonstrated by observational evidence. These cosmological problems were resolved by introducing a brief acceleratedly expanding phase in the very early universe known as inflation. The cosmic inflation by setting the initial conditions of the standard big bang model resolves these problems of the theory. We discuss how the inflationary paradigm solves these problems by proposing the fast expansion period in the early universe. Further inflation and dark energy in fR modified gravity are also reviewed.

scholarly journals Anisotropy of the Microwave Background and Biased Galaxy Formation

1988 ◽  
Vol 130 ◽  
pp. 43-50
Author(s):  
Nick Kaiser
Keyword(s):  
Galaxy Formation ◽  
Large Scale ◽  
Microwave Background ◽  
Galaxy Clustering ◽  
Clear View ◽  
Hot Gas ◽  
Density Perturbations ◽  
The Universe ◽  
Theoretical Developments

Fluctuations in the microwave background will have been imprinted at z ≃ 1000, when the photons and the plasma decoupled. On angular scales greater than a few degrees these fluctuations provide a clear view of any primordial density perturbations, and therefore a clean test of theories which invoke such fluctuations from which to form the structure we see in the universe. On smaller angular scales the predictions are less certain: reionization of the gas may modify the spectrum of the primordial fluctuations, and secondary fluctuations may be generated.Here I shall review some recent theoretical developments. A brief survey is made of the currently popular theories for the primordial perturbations, with emphasis on the predictions for large scale anisotropy. One major uncetainty in the predictions arises from the normalisation of the fluctuations to e.g. galaxy clustering, and much attention is given to the question of ‘biased’ galaxy formation. The effect of reionization on the primordial fluctuations is discussed, as is the anisotropy generated from scattering off hot gas in clusters, groups and galaxies.

scholarly journals COSMOLOGICAL CONSTRAINTS FOR THE COSMIC DEFECT THEORY

2011 ◽  
Vol 20 (06) ◽  
pp. 1039-1051 ◽  
Author(s):  
NINFA RADICELLA ◽  
MAURO SERENO ◽  
ANGELO TARTAGLIA
Keyword(s):  
Large Scale ◽  
Hubble Constant ◽  
Big Bang ◽  
Nuclear Species ◽  
Type Ia ◽  
Species Abundances ◽  
Age Of The Universe ◽  
Ia Supernovae ◽  
The Big Bang ◽  
The Universe

The cosmic defect theory has been confronted with four observational constraints: primordial nuclear species abundances emerging from the big bang nucleosynthesis; large scale structure formation in the Universe; cosmic microwave background acoustic scale; luminosity distances of type Ia supernovae. The test has been based on a statistical analysis of the a posteriori probabilities for three parameters of the theory. The result has been quite satisfactory and such that the performance of the theory is not distinguishable from that of the ΛCDM theory. The use of the optimal values of the parameters for the calculation of the Hubble constant and the age of the Universe confirms the compatibility of the cosmic defect approach with observations.

The First Stars

2013 ◽  
Author(s):  
Abraham Loeb ◽  
Steven R. Furlanetto
Keyword(s):  
Phase Transition ◽  
Early Universe ◽  
Galaxy Formation ◽  
Big Bang ◽  
First Stars ◽  
Complex Chemical ◽  
Radiative Processes ◽  
Complex Processes ◽  
The Big Bang ◽  
The Universe

This chapter considers the emergence of the complex chemical and radiative processes during the first stages of galaxy formation. It studies the appearance of the first stars, their feedback processes, and the resulting ionization structures that emerged during and shortly after the cosmic dawn. The formation of the first stars tens or hundreds of millions of years after the Big Bang had marked a crucial transition in the early Universe. Before this point, the Universe was elegantly described by a small number of parameters. But as soon as the first stars formed, more complex processes entered the scene. To illustrate this, the chapter provides a brief outline of the prevailing (though observationally untested) theory for this cosmological phase transition.

Big Bang Theory

2018 ◽  
Author(s):  
Matthew Y. Heimburger
Keyword(s):  
Large Scale ◽  
Mechanistic Model ◽  
Albert Einstein ◽  
Physical World ◽  
Big Bang ◽  
Scientific Model ◽  
Social Sciences And Humanities ◽  
Big Bang Theory ◽  
The Big Bang ◽  
The Universe

The Big Bang theory is a scientific model of the universe that posits a state of dense, centralized matter before the current, observable expansion of the universe in one giant explosion. While ‘the Big Bang’ was a phrase first used somewhat facetiously by British astronomer Fred Hoyle in 1949, it rested on earlier theories and observations by George Lamaitre, Albert Einstein, and Edwin Hubble. The implications of Big Bang theory have been far-reaching. For some, the Big Bang’s suggestion of a ‘beginning of time’ lent itself to familiar religious teleology. For others, it provided a rigid, mechanistic model of the physical world, which in turn affected ideas in the social sciences and humanities. This is not to say that Big Bang theory was a ‘grand unifying theory’—even in the 1920s, the rather precise predictions of Einstein’s theories of relativity conflicted with the conclusions of Heisenberg’s Uncertainty Principle and quantum mechanics. Still, the idea that the physical world exists due to the violent expansion (and subsequent contraction) of matter suggests a rather small place for humanity in the larger scheme of things. There is little room or need for free will in such a system—at least when it comes to matters of large-scale significance. Today, the Big Bang often stands as a euphemism for debates over God and human determinism in the universe, and lends itself to philosophic traditions such as nihilism and existentialism.

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