Hans Albrecht Bethe
Born: 2 July 1906, Strassburg (now Strasbourg), Germany (now France)
Died: 6 March 2005, Ithaca, NY, USA
Affiliation at the time of the award: Cornell University, Ithaca, NY, USA
Prize motivation: "for his contributions to the theory of nuclear reactions, especially his discoveries concerning the energy production in stars"
Prize share: 1/1
The discovery of fission - the splitting of heavy nuclei - revealed the liberation of large quantities of energy; an effect now exploited in nuclear reactors. This energy is generated by differences in mass. Energy is also liberated when light nuclei combine to form heavier ones, i.e. fusion. In 1938, Hans Bethe proved that fusion produces the enormous energy emitted by stars. He proposed two different processes, both of which result in hydrogen nuclei fusing with helium nuclei.