Sweden
Hannes Alfvén
Alfvén was the founder of the modern field of plasma physics, the study of electrically conducting gases. Plasma is the dominant state of matter in the universe, although it is rare on earth—stars, galaxies and the space between them are filled with plasma. Plasmas have widespread applications in technology, the most exciting being their potential use in controlled thermonuclear fusion, a potentially clean, cheap and unlimited source of energy. Alfvén’s ideas and research in studying the behaviour of plasma are routinely used in the many applications of plasma physics, as is shown by the many concepts that bear his name—Alfvén wave, Alfvén speed, Alfvén limit and so on.