Топик : Steady state theory 

Полнотекстовый поиск по базе:

Главная >> Топик >> Иностранный язык

Steady state theory

Steady state theory

In cosmology, the steady state theory is a model developed in 1949 by Fred Hoyle, Thomas Gold and others as an alternative to the Big Bang theory. Although the model had a large number of supporters among cosmologists in the 1950s and 1960s, the number of supporters decreased markedly in the late 1960s and today it is considered a non-standard cosmology. It is also the basis for another theory known as the quasi-steady state theory which postulates a lot of little big bangs occurring over time. The steady state theory was developed as a result of theoretical calculations that showed that a static universe was impossible under general relativity and observations by Edwin Hubble that the universe was expanding. The steady state theory asserts that although the universe is expanding, it nevertheless does not change its look over time. For this to work, new matter must be formed to keep the density equal over time.

Because only very little matter needs to be formed, roughly a few hundred atoms of hydrogen in the Milky Way Galaxy each year, it is not a problem of the theory that the forming of matter is not observed directly. Despite violating conservation of mass, the steady state theory had a number of attractive features. Most notably, the theory removes the need for the universe to have a beginning.

Problems with the steady-state theory began to emerge in the late 1960s, when observations apparently supported the idea that the universe was in fact changing: quasars and radio galaxies were found only at large distances (i.e., redshift, and thus, because of the finiteness of the speed of light, in the past) not in closer galaxies. Halton Arp, also since the 1960s, has been taking a different view of the data, claiming that evidence can also point to quasars existing as close as the local Virgo cluster.

For most cosmologists, the refutation of the steady-state theory came with the discovery of the cosmic background radiation in 1965, which was predicted by the big bang theory. Within the steady state theory this background radiation is the result of light from ancient stars which has been scattered by galactic dust. However, this explanation has been unconvincing to most cosmologists as the cosmic microwave background is very smooth, making it difficult to explain how it arose from point sources, and the microwave background shows no evidence of features such as polarization which are normally associated with scattering. Furthermore, its spectrum is so close to that of an ideal black body that it could hardly be formed by the superposition of contributions from dust clumps at different temperatures as well as at different redshifts.

As of 2005, the big bang theory is the one that the majority of astronomers consider the best approximation to describing the origin of the universe. In most astrophysical publications, the big bang is implicitly accepted and is used as the basis of more complete theories. At the same time, after the unexpected observation of an accelerating universe in the late-1990s, there were efforts to develop quasi-steady state theories, in which there is not a single big bang but rather multiple big bangs over time which create matter.

Список литературы

Для подготовки данной работы были использованы материалы с сайта http://www.homeenglish.ru/

Похожие работы:

  • Theories of European Integration

    Лабораторная работа >> Иностранный язык
    ... theory emerged, beginning with Stanley Hoffmann’s (1966) claim that the nation-state ... Europe. Constructivism is a notoriously difficult theory to describe succinctly. Indeed, like ... between the two approaches, and a steady stream of empirical studies allowing ...
  • Big Bang theory

    Реферат >> Физика
    ... was expanding. Einstein’s theory updated and revised Newton’s ... theory—since there was no mass in the primordial state ... theory emerged in the years after World War II,. The “steady state ... including Einstein’s General Relativity Theory and quantum mechanics, ...
  • The manager as a teacher: selected aspects of stimulation of scientsfsc thinking

    Дипломная работа >> Менеджмент
    ... cognition. It is often said that theory is generalization of practice, ... Game theory, the theory of fields, the theory of crises, the chaos theory, the theory ... in stationary condition. Consequently, the steady-state process and stationary condition mean ...
  • Criticism of Vladimir Propp’s Theory on Genesis of Magic Fairy Tales’ Structure

    Реферат >> Иностранный язык
    ... to authoritative functions of the state, about political culture. Normative ... falsification (according to Charles Popper's theory). 4. An explication of internal contradictions ... , owing to that an allegedly steady semantic unit becomes blurred (according ...
  • Endogenous Cycle Models

    Контрольная работа >> Иностранный язык
    ... cemented by the income-expenditure theory of Keynes: S = (1-c) Y whereas investment ... relationships, Kaldor superimposed Keynes's multiplier theory: namely, that output changes to ... simple. dK/dt = I (Y, K), thus at steady-state, dK/dt = 0 = I (Y, K) so the ...
  • Synchronization and effect of Zommerfelda as typical resonant samples

    Статья >> Иностранный язык
    ... large, then a very simple stable steady-state motions, inherent in almost linear ... -domain methods for nonlinear analysis. Theory and applications. Singapore: World Sci ... V.F., Klimov D.M. Applied methods in oscillation theory, Moscow: Nauka, 1988: 328 (in ...
  • Физические законы, переменные, принципы

    Реферат >> Физика
    ... stablebut indeed decay. Present theory and experimentation demonstratethat if ... flowsslower. BCS theory (J. Bardeen, L.N. Cooper, J.R. Schrieffer; 1957) A theory put forth to ... Laplace's equation (P. Laplace) For steady-state heat conduction in one dimension ...
  • Интонация

    Реферат >> Иностранный язык
    ... between pitches which are relatively steady-state, i.e. which do not change ... falling (steady-state or rising) pitch with non-finality and related meanings ... the theory of emotions was made by C.Izard. The material ... is steady, upward or downward. The results of the contrastive ...
  • Радиационные пояса

    Статья >> Математика
    ... 282, 2002. Fritz T.A., and Spjeldvik W.N., Steady-state observation of geomagnetically trapped energetic ... 1973. Singer S.F., Trapped albedo neutron theory of the radiation belt, Phys ... Tverskoy B.A., The Earth’s radiation belt theory, Proc. of 9th ICRC, London ...
  • Labour productivity

    Реферат >> Экономика
    ... in Europe. Thus, both economic theory and a quick inspection of a few ... In standard economic growth theory this long-run neutrality proposition has been ... to its balanced steady-state rate by about two tenths of a ...