Hannes Olof Gösta Alfvén
(1908—1995) Swedish theoretical physicist
Swedishphysicist. In the 1930s he developed a theory of sunspot formation based on the idea that under certain conditions a magnetic field can be ‘frozen in’ to a plasma. In 1942 he proposed that waves (now called Alfvén waves) can propagate through a plasma under conditions similar to those found in the Sun's atmosphere. His work inaugurated the study of magnetohydrodynamics, for which he was awarded a share of the 1970 Nobel Prize in Physics.