Astronomy:Emergent Universe
An emergent Universe scenario is a cosmological model that features the Universe being in a low-entropy "dormant" state before the Big Bang or the beginning of the cosmic inflation. Several such scenarios have been proposed in the literature.
"Cosmic egg" scenarios
A popular version proposed by George Ellis and others involves the Universe shaped like a 3-dimensional sphere (or another compact manifold) until a rolling scalar field begins inflating it. These models are notable as potentially avoiding both a Big Bang singularity and a quantum gravity era.[1]
Criticism
This proposal has been criticised by Vilenkin and Mithani[2] and on different grounds by Aguirre and Kehayias[3] as inconsistent if quantum-mechanical effects are taken into account, however, it has been suggested that in more exotic scenarios one or both of these issues might be circumvented.[4]
"Rube Goldberg cosmology" scenario
One of such more exotic emergent Universe scenarios, nicknamed "Rube Goldberg cosmology", features the pre-inflationary Universe shaped like a corridor with two finite (compactified) dimensions and two waves traveling along the third dimension towards each other from past-eternity with the speed of light (likened by the author to two trains loaded with explosives headed for a collision on the same railroad track) that initiate inflation or Big Bang upon colliding.[5][6][7]
References
- ↑ Ellis, George; Maartens, Roy (January 7, 2004). "The Emergent Universe: inflationary cosmology with no singularity". Classical and Quantum Gravity 21 (1): 223–232. doi:10.1088/0264-9381/21/1/015. Bibcode: 2004CQGra..21..223E.
- ↑ Mithani, Audrey T.; Vilenkin, Alexander (January 10, 2012). "Collapse of simple harmonic universe". Journal of Cosmology and Astroparticle Physics 2012 (1): 28. doi:10.1088/1475-7516/2012/01/028. Bibcode: 2012JCAP...01..028M.
- ↑ Aguirre, Anthony; Kehayias, John (November 7, 2013). "Quantum Instability of the Emergent Universe". Physical Review D 88 (10): 103504. doi:10.1103/PhysRevD.88.103504. Bibcode: 2013PhRvD..88j3504A.
- ↑ see e.g. the collection of references in https://www.callidusphilo.com/2021/04/cosmology.html#emergent and https://www.callidusphilo.com/2021/04/cosmology.html#Goldberg
- ↑ https://www.callidusphilo.com/2021/04/cosmology.html#Goldberg
- ↑ Veklych, Bogdan (October 3, 2023). "Is a Quantum Gravity Era Necessary?". International Journal of Modern Theoretical Physics 12 (1): 1–8. https://inspirehep.net/literature/2706047
- ↑ https://www.youtube.com/watch?v=r7txEy8708I
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