# Hoyle–Narlikar theory of gravity

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The **Hoyle–Narlikar theory of gravity**^{[1]} is a Machian and conformal theory of gravity proposed by Fred Hoyle and Jayant Narlikar that originally fits into the quasi steady state model of the universe.^{[2]}

## Description[edit]

The gravitational constant *G* is arbitrary and is determined by the mean density of matter in the universe. The theory was inspired by the Wheeler–Feynman absorber theory for electrodynamics.^{[3]} When Feynman, as a graduate student, lectured on the Wheeler–Feynman absorber theory in the weekly physics seminar at Princeton, Albert Einstein was in the audience and stated at question time that he was trying to achieve the same thing for gravity.^{[4]}

## Incompatible[edit]

Stephen Hawking showed in 1965 that the theory is incompatible with an expanding universe, because the Wheeler-Feynman advanced solution would diverge.^{[5]} However at that time the accelerating expansion of the universe was not known, which resolves the divergence issue because of the cosmic event horizon. The discovery of the accelerated expansion is fairly recent and it earned the Nobel prize in 2011.^{[6]}

## Comparison to Einstein's General Relativity[edit]

The Hoyle-Narlikar theory reduces to Einstein's general relativity in the limit of a smooth fluid model of particle distribution constant in time and space^{[7]}.

Hoyle-Narlikar's theory is consistent with some cosmological tests.^{[8]}

## Hypothesis[edit]

Unlike the standard cosmological model, the quasi steady state hypothesis implies the universe is eternal. According to Narlikar, multiple *mini bangs* would occur at the center of quasars, with various creation fields (or C-field) continuously generating matter out of empty space due to local concentration of negative energy that would also prevent violation of conservation laws, in order to keep the mass density constant as the universe expands.^{[9]}^{[10]} The low-temperature cosmic background radiation would not originate from the Big Bang but from metallic dust made from supernovae, radiating the energy of stars.^{[11]}^{[12]}

## Challenge[edit]

However, the quasi steady-state hypothesis is challenged by observation as it does not fit into WMAP data.^{[13]} If the C-field is not used, ignoring the hypothesis regarding mass creation, the theory is no longer steady state and agrees with WMAP data, as developed in the gravitational absorber theory.

## See also[edit]

- Mach's principle
- Conformal gravity
- Wheeler–Feynman absorber theory
- Brans–Dicke theory
- Non-standard cosmology
- Woodward effect

## Notes[edit]

**^**"Cosmology: Math Plus Mach Equals Far-Out Gravity". Time. Jun 26, 1964. Retrieved 7 August 2010.**^**F. Hoyle; J. V. Narlikar (1964). "A New Theory of Gravitation" (PDF).*Proceedings of the Royal Society A*.**282**(1389): 191–207. Bibcode:1964RSPSA.282..191H. doi:10.1098/rspa.1964.0227.**^**Hoyle, Narlikar (1995). "Cosmology and action-at-a-distance electrodynamics" (PDF).*Reviews of Modern Physics*.**67**(1): 113–155. Bibcode:1995RvMP...67..113H. doi:10.1103/RevModPhys.67.113.**^**Feynman, Richard P. (1985).*Surely You're Joking, Mr. Feynman!*. W. W. Norton & Company. Part II, The Princeton years, pp. 91 et seq. ISBN 978-0393316049.**^**Hawking, S. W. (20 July 1965). "On the Hoyle-Narlikar Theory of Gravitation" (PDF).*Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences*.**286**(1406): 313–319. Bibcode:1965RSPSA.286..313H. doi:10.1098/rspa.1965.0146.**^**Palmer, Jason (2011-10-04). "Nobel physics prize honours accelerating Universe find". BBC. Retrieved 2011-10-05.**^**Rodal, José (May 2019). "A Machian wave effect in conformal, scalar--tensor gravitational theory".*General Relativity and Gravitation*.**51**(5): 64. Bibcode:2019GReGr..51...64R. doi:10.1007/s10714-019-2547-9. ISSN 1572-9532.**^**Canuto, V. M.; Narlikar, J. V. (15 February 1980). "Cosmological tests of the Hoyle-Narlikar conformal gravity" (PDF).*The Astrophysical Journal*.**236**: 6–23. Bibcode:1980ApJ...236....6C. doi:10.1086/157714.**^**Vinodh Ilangovan; K. Manish Sharma; P. Chitra (23 January 2010). "Jayant Narlikar's Cosmology".*NCBS news*.**^**Narlikar, Jayant V. (March 1974). "Mini-bangs in cosmology and astrophysics" (PDF).*Pramana*.**2**(3): 158–170. Bibcode:1974Prama...2..158N. doi:10.1007/BF02847326.**^**J.V. Narlikar; R.G. Vishwakarma; Amir Hajian; Tarun Souradeep; G. Burbidge; F. Hoyle (2003). "Inhomogeneities in the Microwave Background Radiation interpreted within the framework of the Quasi-Steady State Cosmology".*Astrophysical Journal*.**585**(1): 1–11. arXiv:astro-ph/0211036. Bibcode:2003ApJ...585....1N. doi:10.1086/345928.**^**J. V. Narlikar; N. C. Rana (1983). "Cosmic microwave background spectrum in the Hoyle-Narlikar cosmology" (PDF).*Physics Letters A*.**99**(2–3): 75–76. Bibcode:1983PhLA...99...75N. doi:10.1016/0375-9601(83)90927-1.**^**Edward L. Wright. "Errors in the Steady State and Quasi-SS Models". Retrieved 7 August 2010.

## Bibliography[edit]

- Hoyle, Fred; Narlikar, Jayant V.; Freeman, W.H. (1974).
*Action at a distance in physics and cosmology*. W. H. Freeman and Company. ISBN 978-0716703464. - Hoyle, Fred; Narlikar, Jayant V. (1996).
*Lectures on Cosmology and Action at a Distance Electrodynamics*. World Scientific. ISBN 978-9810225582. - Hoyle, Fred; Burbidge, Geoffrey; Narlikar, Jayant V. (2000).
*A Different Approach to Cosmology: From a Static Universe through the Big Bang towards Reality*. Cambridge University Press. ISBN 978-0521662239. - Narlikar, Jayant V. (2002).
*An Introduction to Cosmology*(3rd ed.). Cambridge University Press. ISBN 978-0521793766.