Born on 30 May 1908 in Norrköping, Sweden, Hannes Alfvén was a Nobel Prize–winning scientist who specialized in plasma physics and magnetohydrodynamics. Alfvén studied physics and mathematics at the University of Uppsala, earning his PhD in 1934. After teaching physics at the University of Uppsala and the Nobel Institute for Physics in Stockholm, Alfvén was appointed professor of electromagnetic theory and electric measurements at the Royal Institute of Technology in Stockholm in 1940. In 1967 he accepted a joint professorship at the University of California, San Diego, and spent half of every year in the US and the other half in Sweden until his retirement in 1973. Alfvén made a name for himself with his many innovative and often controversial contributions to the understanding of the structure of the universe. In 1937 he proposed that the galaxy contains a large-scale magnetic field. His proposal was initially dismissed only to be validated decades later. Among other significant discoveries made by Alfvén was that of the eponymous Alfvén wave, a type of magnetohydrodynamic wave that has proved to be fundamentally important in the study of sunspots, aurorae, and general plasma physics. Besides being awarded the Nobel Prize in Physics in 1970 for his work in magnetohydrodynamics, Alfvén received a number of other prestigious awards, such as the Gold Medal of the Royal Astronomical Society in 1967. He was also elected to several scientific societies, including the Royal Swedish Academy of Sciences, the Royal Society of London, and the US National Academy of Sciences. Alfvén became a political and social activist, supporting worldwide disarmament among other causes. He died in 1995 at age 86. (Photo credit: Glasheen Graphics, American Geophysical Union, courtesy AIP Emilio Segrè Visual Archives)
