Editing Hannes Alfvén (section)

== Research ==
In 1937, Alfvén argued that if [[plasma (physics)|plasma]] pervaded the universe, it could then carry electric currents capable of generating a galactic magnetic field.<ref>Hannes Alfvén, 1937 "Cosmic Radiation as an Intra-galactic Phenomenon", ''Ark. f. mat., astr. o. fys.'' 25B, no. 29.</ref> After winning the Nobel Prize for his works in [[magnetohydrodynamics]], he emphasized that:

<blockquote>In order to understand the phenomena in a certain plasma region, it is necessary to map not only the magnetic but also the electric field and the electric currents. Space is filled with a network of currents which transfer energy and momentum over large or very large distances. The currents often pinch to filamentary or surface currents. The latter are likely to give space, as also interstellar and intergalactic space, a cellular structure.<ref>{{cite journal  | last = Hannes | first = A | url = http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1990ITPS...18....5A&amp;db_key=AST&amp;data_type=HTML&amp;format=&amp;high=42ca922c9c32555 | title = Cosmology in the Plasma Universe: An Introductory Exposition | date =1990 | journal = IEEE Transactions on Plasma Science | issn =  0093-3813 | volume = 18  | issue = 1 | pages = 5–10|bibcode = 1990ITPS...18....5P |doi = 10.1109/27.45495 }}</ref></blockquote>

His theoretical work on field-aligned electric currents in the aurora (based on earlier work by [[Kristian Birkeland]]) was confirmed in 1967,<ref>{{cite conference |title=3-dimensional particle-in-cell simulations of spiral galaxies |author=Peratt, A. L. |author2=Peter, W. |author3=Snell, C. M. |conference=Galactic and intergalactic magnetic fields |book-title=Proceedings of the 140th Symposium of IAU |location=Heidelberg, Federal Republic of Germany |date=June 19–23, 1989 |publisher=Kluwer Academic Publishers |pages=143–150 |bibcode=1990IAUS..140..143P }}</ref> these currents now being known as [[Birkeland current]]s.

British scientist [[Sydney Chapman (astronomer)|Sydney Chapman]] was a strong critic of Alfvén.<ref>S. Chapman and J. Bartels, ''Geomagnetism," Vol. 1 and 2, Clarendon Press, Oxford, 1940.</ref> Many physicists regarded Alfvén as espousing [[Fringe science|unorthodox opinions]]<ref>{{cite book | last = Miller | first = DJ | author2 = Hersen M | pages = [https://books.google.com/books?id=sw9QeD-bvJgC&pg=PA10 10] | title = Research Fraud in the Behavioral and Biomedical Sciences | date = 1992 | publisher = John Wiley & Sons | isbn = 978-0-471-52068-9 | url = https://archive.org/details/researchfraudinb0000unse/page/ }}</ref> [[Roger H. Stuewer|R. H. Stuewer]] noting that "... he remained an embittered outsider, winning little respect from other scientists even after he received the Nobel Prize..."<ref>{{cite journal | first = RH | last = Stuewer  | title = Book Reviews | date = 2006 | journal = Physics in Perspective | volume =  8 | issue = 1| pages = 104–112|bibcode = 2006PhP.....8..104S |doi = 10.1007/s00016-005-0251-5 }}</ref> and was often forced to publish his papers in obscure journals. Alfvén recalled:

<blockquote>When I describe [plasma phenomena] according to this formalism most referees do not understand what I say and turn down my papers. With the referee system which rules US science today, this means that my papers are rarely accepted by the leading US journals.<ref>Hannes Alfvén, "Memoirs of a Dissident Scientist", ''American Scientist'', Volume 76, No 3, May–June 1988, pp. 249–251. Quoted in Joseph Paul Martino, ''[https://archive.org/details/sciencefundingpo0000mart/page/131 Science Funding: Politics and Porkbarrel]'' 1992, Transaction Publishers, {{ISBN|1-56000-033-3}}</ref></blockquote>

Alfvén played a central role in the development of:

* [[Plasma physics]]
* [[Charged particle beam]]s
* [[Interplanetary medium]]
* [[Magnetospheric physics]]
* [[Magnetohydrodynamics]]
* [[:Category:Solar phenomena|Solar phenomena]] investigation (such as the [[solar wind]])
* [[Aurora (astronomy)|Aurorae science]]

In 1939, Alfvén proposed the theory of [[geomagnetic storm|magnetic storm]]s and auroras and the theory of [[Plasma (physics)|plasma dynamics]] in the [[Earth]]'s [[magnetosphere]]. This was the paper rejected by the U.S. journal ''Terrestrial Magnetism and Atmospheric Electricity''.

Applications of Alfvén's research in space science include:

* [[Van Allen radiation belt]] theory
* Reduction of the [[Earth's magnetic field]] during [[magnetic storm]]s
* [[Magnetosphere]] (protective plasma covering the Earth)
* Formation of [[comet]] tails
* Formation of the [[Solar System]]
* [[Astrophysical plasma|Dynamics of plasmas in the galaxy]]
* [[Physical cosmology]]

Alfvén's views followed those of the founder of magnetospheric physics, [[Kristian Birkeland]]. At the end of the nineteenth century, Birkeland proposed (backed by extensive data) that electric currents flowing down along the Earth's magnetic fields into the atmosphere caused the aurora and polar magnetic disturbances.

Areas of technology benefiting from Alfvén's contributions include:

* [[Particle accelerator]]s
* Controlled [[thermonuclear fusion]]
* [[Hypersonic flight]]
* [[Rocket]] propulsion
* [[Atmospheric reentry|Reentry]] braking of [[space vehicle]]s

Contributions to astrophysics:

* Galactic magnetic field (1937)
* Identified nonthermal [[synchrotron radiation]] from astronomical sources (1950)

[[Alfvén wave]]s (low [[frequency]] hydromagnetic plasma [[oscillator|oscillations]]) are named in his honor, and propagate at the Alfvén speed. Many of his theories about the solar system were verified as late as the 1980s through external measurements of cometary and planetary magnetospheres. However, Alfvén himself noted that astrophysical textbooks poorly represented known plasma phenomena:

<blockquote>A study of how a number of the most used textbooks in astrophysics treat important concepts such as [[Double layer (plasma)|double layers]], [[critical ionization velocity|critical velocity]], [[pinch effect]]s, and circuits is made. It is found that students using these textbooks remain essentially ignorant of even the existence of these concepts, despite the fact that some of them have been well known for half a century (e.g, double layers, Langmuir, 1929; pinch effect, Bennet, 1934).<ref>Hannes Alfvén, "[http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1986ITPS...14..779A&amp;db_key=AST&amp;data_type=HTML&amp;format=&amp;high=42ca922c9c02197 Double layers and circuits in astrophysics]" (1986) ''IEEE Transactions on Plasma Science'' (ISSN 0093-3813), vol. PS-14, Dec. 1986, pp. 779–793.</ref></blockquote>

Alfvén reported that of 17 of the most used textbooks on astrophysics, none mention the pinch effect, none mentioned critical ionization velocity, only two mentioned circuits, and three mentioned double layers.

Alfvén believed the problem with the [[Big Bang]] was that astrophysicists tried to extrapolate the origin of the universe from [[mathematical theory|mathematical theories]] developed on the blackboard, rather than starting from known observable phenomena. He also considered the Big Bang to be a [[mythology|myth]] devised to explain creation.<ref>{{cite journal |first=Hannes |last=Alfvén |title=Cosmology—Myth or Science? |journal= Journal of Astrophysics and Astronomy|volume=5 |issue=1 |pages=79–98 |year=1984 |doi=10.1007/BF02714974 |bibcode=1984JApA....5...79A |s2cid=122751100 }}</ref> Alfvén and colleagues proposed the [[Alfvén–Klein cosmology|Alfvén–Klein model]] as an alternative [[physical cosmology|cosmological]] theory to both the [[Big Bang]] and [[steady state theory]] cosmologies.