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". 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, some cyclic models.
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 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.
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
- Jean-Luc Lehners (2010) "Ekpyrotic Nongaussianity: A Review" Advances in Astronomy 2010:903907, 19 pp.
- Justin Khoury and Paul J. Steinhardt (2010) "Adiabatic Ekpyrosis: Scale-Invariant Curvature Perturbations from a Single Scalar Field in a Contracting Universe" Phys. Rev. Lett. 104(9):91301, 4 pp. (preprint)
- 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.
- 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