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The ekpyrotic universe, or ekpyrotic scenario, is a cosmological model of the origin and shape of the universe. The name comes from a Stoic term ekpyrosis (Ancient Greek ἐκπύρωσις ekpurōsis) meaning conflagration or in Stoic usage "conversion into fire".[1] The ekpyrotic model of the universe is an alternative to the standard cosmic inflation model for the very early universe; both models accommodate the standard big bang Lambda-CDM model of our universe. The ekpyrotic model is a precursor to, and part of the cyclic model.

The ekpyrotic model came out of work by Neil Turok and Paul Steinhardt and maintains that the universe did not start in a singularity, but came about from the collision of two branes. This collision avoids the primordial singularity and superluminal expansion while preserving nearly scale-free density fluctuations and other features of the observed universe. The ekpyrotic model is cyclic, though collisions between branes are rare on the time scale of the expansion of the universe to a nearly featureless flat expanse. Observations that may distinguish between the ekpyrotic and inflationary models include polarization of the cosmic microwave background radiation and frequency distribution of the gravitational wave spectrum.[2][3]

Notes and references

^ 'the dissolution of the universe into fire'. In Stoic philosophy, ekpyrosis, all-engulfing cosmic fire, represents the contractive phase of eternally-recurring destruction and re-creation. On "ekpyrosis" see generally Michael Lapidge, 'Stoic Cosmology,' in John M. Rist, The Stoics, Cambridge University Press, 1978 pp.161-186, pp.180-184
^ Steinhardt, Paul J.; Neil Turok (24 May 2002). "Cosmic evolution in a cyclic universe". Physical Review D 65 (12): 126003. arXiv:hep-th/0111098. Bibcode 2002PhRvD..65l6003S. doi:10.1103/PhysRevD.65.126003.
^ Khoury, Justin; Burt A. Ovrut, Paul J. Steinhardt, Neil Turok (28 Nov 2001). "Ekpyrotic universe: Colliding branes and the origin of the hot big bang". Physical Review D 64 (12): 123522. arXiv:hep-th/0103239. Bibcode 2001PhRvD..64l3522K. doi:10.1103/PhysRevD.64.123522.


See also

Cosmic inflation
Cyclic model


Further reading

P. J. Steinhardt and N. Turok, Endless Universe: Beyond the Big Bang, (Doubleday, 2007)
A Brief Introduction to the Ekpyrotic Universe Steinhardt, Paul J., Department of Physics, Princeton University
Greene, Brian, The Elegant Universe: Superstrings, Hidden Dimensions, and the Quest for the Ultimate Theory, Vintage (2000).
Kallosh, Renata, Kofman, Lev and Linde, Andrei, Pyrotechnic Universe (the first paper to point out problems with the theory)
Whitehouse, David, "Before the Big Bang". BBC News. April 10, 2001.
Discover Magazine, Before the Big Bang February 2004 issue.
Parallel Universes, (BBC Two 9.00pm Thursday February 14, 2002)
'Brane-Storm' Challenges Part of Big Bang Theory

Astronomy Encyclopedia

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