The Development of Physical Cosmology

Author(s):  
P. J. E. Peebles

This chapter introduces physical cosmology as the attempt to make sense of the large-scale nature of the material world by the methods of the natural sciences. It explains that physical cosmology operates under the special restrictions of astronomy, which is considered successful in sister fields, such as stellar astronomy and particle physics. It cites the substantial progress of cosmology as an enterprise in physical science, although the advances certainly have moved around considerable gaps in one's understanding. The chapter details how cosmology inherits from basic physics the more ancient and honorable tradition of attempts to understand where the world came from, where it is going, and why. It reviews believable evidence that the universe is expanding, the space between the galaxies opening up, and that this expansion traces back to a hot dense phase, the big bang.

Universe ◽  
2021 ◽  
Vol 7 (8) ◽  
pp. 276
Author(s):  
Muhammad Zahid Mughal ◽  
Iftikhar Ahmad ◽  
Juan Luis García Guirao

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.


2011 ◽  
Vol 20 (06) ◽  
pp. 1039-1051 ◽  
Author(s):  
NINFA RADICELLA ◽  
MAURO SERENO ◽  
ANGELO TARTAGLIA

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.


Author(s):  
Matthew Y. Heimburger

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.


1994 ◽  
Vol 159 ◽  
pp. 293-299
Author(s):  
G. Burbidge ◽  
F. Hoyle ◽  
J.V. Narlikar

The standard big bang cosmology has the universe created out of a primeval explosion that not only created matter and radiation but also spacetime itself. The big bang event itself cannot be discussed within the framework of a physical theory but the events following it are in principle considered within the scope of science. The recent developments on the frontier between particle physics and cosmology highlight the attempts to chart the history of the very early universe.


Matter in the Universe can be detected either by the radiation it emits or by its gravitational influence. There is a strong suggestion that the Universe contains substantial hidden matter, mass without corresponding light. There are also arguments from elementary particle physics that the Universe should have closure density, which would also imply hidden mass. Observations of the chemical composition of the Universe interpreted in terms of the hot Big Bang cosmological theory suggest that this hidden matter cannot all be of baryonic form but must consist of weakly interacting elementary particles. A combination of observations and theoretical ideas about the origin of large-scale structure may demand that these particles are of a type which is not yet definitely known to exist.


1974 ◽  
Vol 63 ◽  
pp. 157-162 ◽  
Author(s):  
R. B. Partridge

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.


1988 ◽  
Vol 7 (1) ◽  
pp. 48-54
Author(s):  
J. P. F. Sellschop

The origin of the universe and nuclear synthesis are discussed in this paper. The concept of the “Big Bang” is introduced in cosmology from observational evidence that the universe is expanding. The language of elementary particle physics is used to describe the evolution of the universe starting at a very small fraction of a second after the "Big Bang”. Various “Eras” are identified during which certain nuclear processes predominate. At a later stage the remarkable nuclear synthesis of carbon takes place, leading to the evolution of other elements. Neutrino measurements are important to validate physical theories in this field and some results of such measurements by the WITS-CSIR Schonland Research Centre are presented.


Author(s):  
E. N. GORLOVA ◽  
R. V. TKACHENKO

International scientific projects aimed at the creation and operation of megasiens class facilities and, accordingly, at obtaining breakthrough, innovative scientific results of global significance are called megascience class projects. Currently, there are several large-scale megasiens projects in the world, each of which is aimed at addressing the global challenge facing humanity. The next qualitative stage in the development of civilization is impossible without the elimination of bottlenecks that prevent such a progressive movement. One of the most pressing global problems is to increase energy efficiency and develop technologies for obtaining and using alternative renewable sources of electric and thermal energy, as well as gaining new knowledge about the structure of matter and the evolution of the Universe from the Big Bang to the present. The megascience projects of ITER and FAIR are called to solve these problems, an important role in the financing and technical implementation of which is played by the Russian Federation.


1996 ◽  
Vol 168 ◽  
pp. 31-44
Author(s):  
G.F. Smoot

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.


Author(s):  
Nicholas Manton ◽  
Nicholas Mee

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.


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