Steady-state model
The steady-state model is a former theory in cosmology which held that the universe is expanding but does not change over time, because new matter is continuously created as it expands.[1] It is most closely linked with the Cambridge physicists Fred Hoyle, Hermann Bondi and Thomas Gold.[1] Astronomical observations later ruled it out.[2]
Origins
In the late 1940s, Hoyle, Bondi and Gold became concerned about well-known problems with the "evolving" models of the expanding universe.[3] In 1948 Bondi and Gold published a paper arguing that there must be a continuous creation of matter in space, at a rate far too low to observe directly.[4]
Bondi and Gold based their model on the "perfect cosmological principle": the idea that the universe should look essentially the same to all observers, in all places and at all times. For an expanding universe, this principle required matter to be created continuously.[5] Their theory was not built on general relativity.[6] Hoyle took a different route: he changed Einstein's field equations, replacing the cosmological constant with a new "creation-field" term that stood for matter forming continuously from the vacuum.[7]
Debate and decline
During the 1950s and 1960s there was a major debate between supporters of the steady-state model and supporters of evolving models of the universe.[8] In the end, steady-state models were ruled out by astronomical observations showing clearly that the universe is evolving over time.[9] Hoyle later proposed a modified "quasi steady-state" theory with Geoffrey Burbidge and Jayant Narlikar, in which the steady-state universe contains many local "little bangs".[10]
Einstein's unpublished model
Albert Einstein also once attempted a steady-state model.[11] Several features of his unpublished manuscript suggest that it was written in early 1931.[12] There is no evidence that Hoyle, Bondi or Gold knew about it.[13]
References
- ↑ 1.0 1.1 O'Raifeartaigh, Cormac; Mitton, Simon (2015). "A new perspective on steady-state cosmology: from Einstein to Hoyle". arXiv. arXiv:1506.01651. Retrieved 20 October 2026.
The concept of an expanding universe that remains in a steady-state due to a continuous creation of matter is most strongly associated with the Cambridge physicists Fred Hoyle, Hermann Bondi and Thomas Gold.
- ↑ O'Raifeartaigh, Cormac; Mitton, Simon (2015). "A new perspective on steady-state cosmology: from Einstein to Hoyle". arXiv. arXiv:1506.01651. Retrieved 20 October 2026.
Eventually, steady-state models were ruled out by astronomical observations
- ↑ O'Raifeartaigh, Cormac; Mitton, Simon (2015). "A new perspective on steady-state cosmology: from Einstein to Hoyle". arXiv. arXiv:1506.01651. Retrieved 20 October 2026.
In the late 1940s, these physicists became concerned with well-known problems associated with evolving models of the expanding cosmos.
- ↑ Bondi, Hermann; Gold, Thomas (1948). "The Steady-State Theory of the Expanding Universe". Monthly Notices of the Royal Astronomical Society. 108: 252. Retrieved 20 October 2026.
there must be continuous creation of matter in space at a rate which is, however, far too low for direct observation.
- ↑ O'Raifeartaigh, Cormac; Mitton, Simon (2015). "A new perspective on steady-state cosmology: from Einstein to Hoyle". arXiv. arXiv:1506.01651. Retrieved 20 October 2026.
a principle that posited that the universe should appear essentially the same to all observers in all places at all times. For an expanding universe, this principle demanded the postulate of a continuous creation of matter.
- ↑ O'Raifeartaigh, Cormac; Mitton, Simon (2015). "A new perspective on steady-state cosmology: from Einstein to Hoyle". arXiv. arXiv:1506.01651. Retrieved 20 October 2026.
the Bondi-Gold theory was not formulated in the context of general relativity.
- ↑ O'Raifeartaigh, Cormac; Mitton, Simon (2015). "A new perspective on steady-state cosmology: from Einstein to Hoyle". arXiv. arXiv:1506.01651. Retrieved 20 October 2026.
Replacing the cosmological constant with a new 'creation-field' term Cik, representing the continuous formation of matter from the vacuum
- ↑ O'Raifeartaigh, Cormac; Mitton, Simon (2015). "A new perspective on steady-state cosmology: from Einstein to Hoyle". arXiv. arXiv:1506.01651. Retrieved 20 October 2026.
a significant debate was waged between steady-state and evolving models of the cosmos during the 1950s and 1960s
- ↑ O'Raifeartaigh, Cormac; Mitton, Simon (2015). "A new perspective on steady-state cosmology: from Einstein to Hoyle". arXiv. arXiv:1506.01651. Retrieved 20 October 2026.
that showed unequivocally that we inhabit a universe that is evolving over time.
- ↑ O'Raifeartaigh, Cormac; Mitton, Simon (2015). "A new perspective on steady-state cosmology: from Einstein to Hoyle". arXiv. arXiv:1506.01651. Retrieved 20 October 2026.
a modified theory known as the 'quasi steady-state universe', in which the steadystate universe is permeated with local little bangs (Hoyle, Burbidge and Narlikar 1993).
- ↑ O'Raifeartaigh, Cormac; Mitton, Simon (2015). "A new perspective on steady-state cosmology: from Einstein to Hoyle". arXiv. arXiv:1506.01651. Retrieved 20 October 2026.
it is likely that they would have been greatly intrigued to learn that Einstein had once attempted a steady-state model
- ↑ O'Raifeartaigh, Cormac; Mitton, Simon (2015). "A new perspective on steady-state cosmology: from Einstein to Hoyle". arXiv. arXiv:1506.01651. Retrieved 20 October 2026.
several aspects of Einstein's steady-state manuscript suggest that it was written in early 1931
- ↑ O'Raifeartaigh, Cormac; Mitton, Simon (2015). "A new perspective on steady-state cosmology: from Einstein to Hoyle". arXiv. arXiv:1506.01651. Retrieved 20 October 2026.
there is no evidence to suggest that any of the steady-state theorists were aware of the manuscript under discussion