Hannes Olof Gösta Alfvén (Swedish: [al've:n]; 30 May 1908 - 2 April 1995) was a Swedish electrical engineer, plasma physicist and winner of the 1970 Nobel Prize in Physics for his work on magnetohydrodynamics (MHD). He described the class of MHD waves now known as Alfvén waves. He was originally trained as an electrical power engineer and later moved to research and teaching in the fields of plasma physics and electrical engineering. Alfvén made many contributions to plasma physics, including theories describing the behavior of aurorae, the Van Allen radiation belts, the effect of magnetic storms on the Earth's magnetic field, the terrestrial magnetosphere, and the dynamics of plasmas in the Milky Way galaxy.
Video Hannes Alfvén
Education
Alfvén received his PhD from the University of Uppsala in 1934. His thesis was titled "Investigations of the Ultra-short Electromagnetic Waves."
Maps Hannes Alfvén
Early years
In 1934, Alfvén taught physics at both the University of Uppsala and the Nobel Institute for Physics (later renamed the Manne Siegbahn Institute of Physics) in Stockholm, Sweden. In 1940, he became professor of electromagnetic theory and electrical measurements at the Royal Institute of Technology in Stockholm. In 1945, he acquired the nonappointive position of Chair of Electronics. His title was changed to Chair of Plasma Physics in 1963. From 1954 to 1955, Alfvén was a Fulbright Scholar at the University of Maryland, College Park. In 1967, after leaving Sweden and spending time in the Soviet Union, he moved to the United States. Alfvén worked in the departments of electrical engineering at both the University of California, San Diego and the University of Southern California.
Later years
In 1991, Alfvén retired as professor of electrical engineering at the University of California, San Diego and professor of plasma physics at the Royal Institute of Technology in Stockholm.
Alfvén spent his later adult life alternating between California and Sweden. He died at the age of 86.
Research
In 1937, Alfvén argued that if plasma pervaded the universe, it could then carry electric currents capable of generating a galactic magnetic field. After winning the Nobel Prize for his works in magnetohydrodynamics, he emphasized that:
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.
His theoretical work on field-aligned electric currents in the aurora (based on earlier work by Kristian Birkeland) was confirmed in 1967, these currents now being known as Birkeland currents.
Alfvén's work was disputed for many years by the senior scientist in space physics, the British mathematician and geophysicist Sydney Chapman. Alfvén's disagreements with Chapman stemmed in large part from trouble with the peer review system. Alfvén rarely benefited from the acceptance generally afforded senior scientists in scientific journals. He once submitted a paper on the theory of magnetic storms and auroras to the American journal Terrestrial Magnetism and Atmospheric Electricity only to have his paper rejected on the ground that it did not agree with the theoretical calculations of conventional physics of the time. He was regarded as a person with unorthodox opinions in the field by many physicists, R. H. Stuewer noting that "... he remained an embittered outsider, winning little respect from other scientists even after he received the Nobel Prize..." and was often forced to publish his papers in obscure journals. Alfvén recalled:
When I describe the [plasma phenomena] according to this formulism 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.
Alfvén played a central role in the development of:
- Plasma physics
- Charged particle beams
- Interplanetary medium
- Magnetospheric physics
- Magnetohydrodynamics
- Solar phenomena investigation (such as the solar wind)
- Aurorae science
In 1939, Alfvén proposed the theory of magnetic storms and auroras and the theory of 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 storms
- Magnetosphere (protective plasma covering the earth)
- Formation of comet tails
- Formation of the solar system
- 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 accelerators
- Controlled thermonuclear fusion
- Hypersonic flight
- Rocket propulsion
- Reentry braking of space vehicles
Contributions to astrophysics:
- Galactic magnetic field (1937)
- Identified nonthermal synchrotron radiation from astronomical sources (1950)
Alfvén waves (low frequency hydromagnetic plasma oscillations) are named in his honor. Many of his theories about the solar system were verified as late as the 1980s through external measurements of cometary and planetary magnetospheres. But Alfvén himself noted that astrophysical textbooks poorly represented known plasma phenomena:
A study of how a number of the most used textbooks in astrophysics treat important concepts such as double layers, critical velocity, pinch effects, 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).
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 theories developed on the blackboard, rather than starting from known observable phenomena. He also considered the Big Bang to be a myth devised to explain creation. Alfvén and colleagues proposed the Alfvén-Klein model as an alternative cosmological theory to both the Big Bang and steady state theory cosmologies.
Personal life
Alfvén had a good sense of humor, and he participated in a variety of social issues and worldwide disarmament movements. He had a long-standing distrust of computers. Alfvén studied the history of science, oriental philosophy, and religion. On his religious views, Alfven was irreligious and critical of religion. He spoke Swedish, English, German, French, and Russian, and some Spanish and Chinese. He expressed great concern about the difficulties of permanent high-level radioactive waste management." Alfvén was also interested in problems in cosmology and all aspects of auroral physics, and used Schröder's well known book on aurora, Das Phänomen des Polarlichts. Letters of Alfvén, Treder, and Schröder were published on the occasion of Treder's 70th birthday. A long paper on changes in auroral theories was published by Wilfried Schröder in honor of Hannes Alfvén's 80th birthday in the German scientific journal Gerlands Beiträge zur Geophysik in 1988. The relationships between Hans-Jürgen Treder, Hannes Alfvén and Wilfried Schröder were discussed in detail by Schröder in his publications.
Alfvén was married for 67 years to his wife Kerstin (1910-1992). They raised five children, one boy and four girls. His son became a physician, while one daughter became a writer and another a lawyer in Sweden. The composer Hugo Alfvén was Hannes Alfvén's uncle.
Awards and honours
The Hannes Alfvén Prize, awarded annually by the European Physical Society for outstanding contributions in plasma physics, is named after him. The asteroid 1778 Alfvén is named in his honour.
Awards
Alfvén was one of the few scientists who was a foreign member of both the United States and Soviet Academies of Sciences.
Selected bibliography
For full list of publications see.
- Books
- Articles
References
External links
- Hannes Alfvén biography
- Hannes Alfvén at the Nobel Foundation, inc. Biography, Nobel lecture and Banquet speech
- Hannes Alfvén biography (Royal Institute of Technology in Stockholm, Sweden)
- Hannes Alfvén Biographical Memoirs (Proceedings of the American Philosophical Society)
- Papers of Hannes Olof Gosta Alfvén
- Hannes Alfvén Medal - awarded for outstanding scientific contributions towards the understanding of plasma processes in the solar system and other cosmical plasma environments
- Timeline of Nobel Prize Winners: Hannes Olof Gosta Alfvén
- Hannes Alfvén Papers (1945-1991) in the Mandeville Special Collections Library.
- Weisstein, Eric Wolfgang (ed.). "Alfvén, Hannes (1908-1995)". ScienceWorld.
- QJRAS Obituary 37 (1996) 259
- Hannes Alfvén Birth Centennial 30 May 2008 (2008)
Source of the article : Wikipedia
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