Editing Plasma cosmology (section)

==Alfvén–Klein cosmology<!--'Alfvén–Klein cosmology', 'Alfvén–Klein model', 'Klein–Alfvén cosmology', and 'Ambiplasma' redirect here-->==
[[Image:Cosmic-triple-jump.svg|thumb|200px|[[Hannes Alfvén]] suggested that [[Plasma scaling|scaling]] laboratory results can be extrapolated up to the scale of the universe. A scaling jump by a factor 10<sup>9</sup> was required to extrapolate to the [[magnetosphere]], a second jump to extrapolate to galactic conditions, and a third jump to extrapolate to the [[Hubble's law#Hubble length|Hubble distance]].<ref name=scaling>{{cite journal 
|last1=Alfvén
|first1=Hannes
|date=1983
|title=On hierarchical cosmology 
|journal=Astrophysics and Space Science
|volume=89
|issue=2
|pages=313–324
|bibcode=1983Ap&SS..89..313A|doi=10.1007/bf00655984 |s2cid=122396373
}}</ref>]]

In the 1960s, the theory behind plasma cosmology was introduced by Alfvén,<ref name="Alfven1966" >{{cite book
|first=Alfvén |last=H.
|title=Worlds-antiworlds: antimatter in cosmology
|publisher=Freeman
|date=1966 }}</ref> a plasma expert who won the 1970 [[Nobel Prize in Physics]] for his work on [[magnetohydrodynamics]].<ref name="Kragh1996" /> He proposed the use of [[plasma scaling]] to extrapolate the results of laboratory experiments and [[plasma (physics)|plasma physics]] observations and scale them over many [[Order of magnitude|orders of magnitude]] up to the largest observable objects in the universe (see box<ref name=scaling/>).<ref name="Alfvenpu1987">{{cite journal
|last1=Alfven | first1=H.O G
|title=Plasma universe
|journal=Physica Scripta
|volume=T18
|pages=20–28
|url=http://plasmauniverse.info/downloads/AlfvenPlasmaUniverse.pdf
|date= 1987
 |doi=10.1088/0031-8949/1987/t18/002|bibcode = 1987PhST...18...20A | s2cid=250828260
}}</ref> In 1971, [[Oskar Klein]], a Swedish theoretical physicist, extended the earlier proposals and developed the Alfvén–Klein model of the [[universe]],<ref>{{cite journal
|last1=Klein|first1=O.
|title=Arguments concerning relativity and cosmology
|journal=Science 
|volume=171 
|issue=3969
|pages=339–45
|doi=10.1126/science.171.3969.339
|bibcode=1971Sci...171..339K
|pmid=17808634
|date=1971|s2cid=22308581
}}</ref> or "metagalaxy", an earlier term used to refer to the empirically accessible part of the universe, rather than the entire universe including parts beyond our [[particle horizon]].<ref name="Alfven1963">{{cite book
|last1=Alfvén|first1=H.
|last2=Falthammar|first2=C.-G. 
|title=Cosmic electrodynamics
|publisher=Clarendon Press
|location=Oxford
|date=1963}}</ref><ref name="Kragh1996">{{cite book  	
|last=Kragh
|first=H.S.
|title=Cosmology and Controversy: The Historical Development of Two Theories of the Universe
|volume=23
|pages=482–483
|isbn=978-0-691-00546-1
|publisher=Princeton University Press
|url=https://books.google.com/books?id=f6p0AFgzeMsC&pg=PA384
|date=1996}}</ref>

In this model, the universe is made up of equal amounts of matter and [[antimatter]] with the boundaries between the regions of matter and antimatter being delineated by cosmic [[electromagnetic field]]s formed by [[Double layer (plasma physics)|double layers]], thin regions comprising two parallel layers with opposite electrical charge. Interaction between these boundary regions would generate radiation, and this would form the plasma. Alfvén introduced the term '''ambiplasma'''<!--boldface per WP:R#PLA--> for a plasma made up of matter and antimatter and the double layers are thus formed of ambiplasma. According to Alfvén, such an ambiplasma would be relatively long-lived as the component particles and antiparticles would be too hot and too low-density to annihilate each other rapidly. The double layers will act to repel clouds of opposite type, but combine clouds of the same type, creating ever-larger regions of matter and antimatter. The idea of ambiplasma was developed further into the forms of heavy ambiplasma (protons-antiprotons) and light ambiplasma (electrons-positrons).<ref name="Alfven1966" />

Alfvén–Klein cosmology was proposed in part to explain the observed [[baryon asymmetry]] in the universe, starting from an [[initial condition]] of exact [[symmetry]] between matter and antimatter. According to Alfvén and Klein, ambiplasma would naturally form pockets of matter and pockets of antimatter that would expand outwards as annihilation between matter and antimatter occurred in the double layer at the boundaries. They concluded that we must just happen to live in one of the pockets that was mostly [[baryon]]s rather than antibaryons, explaining the baryon asymmetry. The pockets, or bubbles, of matter or antimatter would expand because of annihilations at the boundaries, which Alfvén considered as a possible explanation for the observed [[expansion of the universe]], which would be merely a local phase of a much larger history. Alfvén postulated that the universe has always existed <ref name="Alfven1988">{{cite web 
|last1=Alfvén |first1=H.
|title=Has the Universe an Origin? (Trita-EPP)
|volume=7 
|page=6
|url=http://www.iaea.org/inis/collection/NCLCollectionStore/_Public/20/047/20047579.pdf  
|date=1988}}</ref><ref name=Peratt>{{cite journal
|last1=Peratt|first1=A.L.
|title=Introduction to Plasma Astrophysics and Cosmology 
|journal=Astrophysics and Space Science
|volume=227
|issue=1–2
|pages=3–11 
|bibcode=1995Ap&SS.227....3P 
|doi=10.1007/bf00678062
|url = http://www.plasmauniverse.info/downloads/PrincetonEditorial.1993.pdf
|date=1995|isbn=978-94-010-4181-2
|s2cid=118452749
}}</ref> due to [[causality]] arguments and the rejection of ''[[ex nihilo]]'' models, such as the [[Big Bang]], as a stealth form of [[creationism]].<ref name="Alfven1992">{{cite journal
|last1=Alfvén |first1=H.
|title=Cosmology: Myth or Science?
|journal=IEEE Transactions on Plasma Science
|volume=20
|issue=6
|pages=590–600
|bibcode=1992ITPS...20..590A
|doi=10.1109/27.199498
|year=1992 
}}</ref><ref name="Alfven1984">{{cite journal
|last1=Alfvén|first1=H.
|title=Cosmology - Myth or science? 
|journal=Journal of Astrophysics and Astronomy
|volume=5
|issue=1
|pages=79–98
|issn=0250-6335
|bibcode = 1984JApA....5...79A
|doi=10.1007/BF02714974
|date=1984|s2cid=122751100
}}</ref> The exploding double layer was also suggested by Alfvén as a possible mechanism for the generation of [[cosmic rays]],
<ref name="Alfven1981">{{cite book
|first=Alfvén |last=H.
|title=Cosmic plasma
|pages=IV.10.3.2, 109
|publisher=Taylor & Francis
|date=1981}} recount: "Double layers may also produce extremely high energies. This is known to take place in solar flares, where they generate solar cosmic rays up to 10<sup>9</sup> to 10<sup>10</sup> eV."</ref> [[X-ray burster|X-ray bursts]] and [[gamma-ray burst]]s.<ref name="Alfven1986">{{cite journal
|last1=Alfvén |first1=H.
|title=Double layers and circuits in astrophysics
|journal=IEEE Transactions on Plasma Science
|volume=PS-14
|issue=6
|pages=779–793
|date=1986
 |bibcode=1986ITPS...14..779A|doi = 10.1109/TPS.1986.4316626 |s2cid=11866813
|url=https://cds.cern.ch/record/169085
|hdl=2060/19870005703
|hdl-access=free
}}</ref>

In 1993, theoretical cosmologist [[Jim Peebles]] criticized Alfvén–Klein cosmology, writing that "there is no way that the results can be consistent with the isotropy of the [[cosmic microwave background|cosmic microwave background radiation]] and [[X-ray background]]s".<ref name="Peebles1993">{{cite book
|last=Pebbles|first=P.J.E.
|title=Principles of Physical Cosmology
|publisher=Princeton University Press
|pages=207
|isbn=978-0-691-07428-3
|date=1993}}</ref>  In his book he also showed that Alfvén's models do not predict [[Hubble's law]], [[Big Bang nucleosynthesis|the abundance of light elements]], or the existence of the [[cosmic microwave background]]. A further difficulty with the ambiplasma model is that matter–antimatter [[annihilation]] results in the production of high energy [[photon]]s, which are not observed in the amounts predicted. While it is possible that the local "matter-dominated" cell is simply larger than the [[observable universe]], this proposition does not lend itself to observational tests.