Steady State theory

This article is about the cosmological theory. For other uses, see Steady state (disambiguation).

In cosmology, the Steady State theory is a now-obsolete[1] expanding universe model alternative to the Big Bang theory of the Universe and its origin. In steady state views, new matter is continuously created as the Universe expands, thus adhering to the perfect cosmological principle (the principle that the observable universe is basically the same in any time as well as any place).

While the steady state model enjoyed some popularity in the mid-20th century, it is now rejected by the vast majority of cosmologists, astrophysicists and astronomers, as the observational evidence points to a Big Bang-type cosmology with a finite age of the universe, which the Steady State theory does not predict.[2]

Sir James Jeans, in the 1920s, was the first to conjecture a steady state cosmology based on a hypothesized continuous creation of matter in the Universe.[3] Theoretical calculations showed that a static universe was impossible under general relativity, and observations by Edwin Hubble had shown that the Universe was expanding. The steady state theory asserts that although the Universe is expanding, it nevertheless does not change its appearance over time (the perfect cosmological principle); the Universe has no beginning and no end.

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 (therefore could have existed only in the distant past), not in closer galaxies. Whereas the Big Bang theory predicted as much, the Steady State theory predicted that such objects would be found throughout the Universe, including close to our own galaxy.

Quasi-steady state

Quasi-steady state cosmology (QSS) was proposed in 1993 by Fred Hoyle, Geoffrey Burbidge, and Jayant V. Narlikar as a new incarnation of the steady state ideas meant to explain additional features unaccounted for in the initial proposal. The theory suggests pockets of creation occurring over time within the Universe, sometimes referred to as minibangs, mini-creation events, or little bangs. After the observation of an accelerating universe, further modifications of the model were made.[4]

For most cosmologists, the refutation of the steady-state theory came with the discovery of the cosmic microwave background radiation in 1965, which was predicted by the Big Bang theory. Stephen Hawking described this discovery as "the final nail in the coffin of the steady-state theory." The steady-state theory explained microwave background radiation as the result of light from ancient stars that has been scattered by galactic dust. However, the cosmic microwave background level is very even in all directions, making it difficult to explain how it could be generated by numerous point sources and the microwave background radiation shows no evidence of characteristics such as polarization that 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 a multitude of dust clumps at different temperatures as well as at different redshifts. Steven Weinberg wrote in 1972,

The steady state model does not appear to agree with the observed dL versus z relation or with source counts ... In a sense, this disagreement is a credit to the model; alone among all cosmologies, the steady-state model makes such definite predictions that it can be disproved even with the limited observational evidence at our disposal. The steady-state model is so attractive that many of its adherents still retain hope that the evidence against it will eventually disappear as observations improve. However, if the cosmic microwave radiation . . . is really black-body radiation, it will be difficult to doubt that the universe has evolved from a hotter denser early stage.

Since this discovery, the Big Bang theory has been considered to provide the best explanation of 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.

Criticism

Astrophysicist and cosmologist Ned Wright has pointed out flaws in the theory (as shown).[5] These first comments were soon rebutted by the proponents.[6] Wright and other mainstream cosmologists reviewing QSS have pointed out new flaws and discrepancies with observations left unexplained by proponents.[7]

See also

Notes and citations

  1. ↑ "Steady State theory". BBC. Retrieved January 11, 2015. [T]he Steady State theorists' ideas are largely discredited today...
  2. ↑ Cosmology and Controversy: The Historical Development of Two Theories of the Universe - Helge Kragh Princeton University Press, 1999
  3. ↑ Astronomy and Cosmogony, Cambridge U Press, p /steady-state-theory steady-state theory (cosmology) -- Britannica Online Encyclopedia]
  4. ↑ Narlikar, J. V.; Vishwakarma, R. G.; Burbidge, G. (2002). "Interpretations of the Accelerating Universe". arXiv:astro-ph/0205064 [astro-ph].
  5. ↑ Wright, E. L. (1994). "Comments on the Quasi-Steady-State Cosmology". arXiv:astro-ph/9410070 [astro-ph].
  6. ↑ Hoyle, F.; Burbidge, G.; Narlikar, J. V. (1994). "Note on a Comment by Edward L. Wright". arXiv:astro-ph/9412045 [astro-ph].
  7. ↑ Wright, E. L. (20 December 2010). "Errors in the Steady State and Quasi-SS Models". UCLA, Physics & Astronomy Department.

Further reading

Criticism