Hans Bethe
Hans Bethe worked out how stars produce energy and spent his later life arguing against nuclear weapons. Born in Strasbourg in 1906 to a physiologist father and a Jewish mother, he took his doctorate under Arnold Sommerfeld in Munich and was dismissed from his post at Tübingen in 1933 under the Nazi racial laws. He reached Cornell in 1935 and stayed there for the rest of his career. In 1938, after a conference on stellar energy, he worked out the nuclear reactions that power stars — the proton-proton chain in smaller stars and the carbon-nitrogen-oxygen cycle in larger ones — which explained where sunlight comes from and how long a star can last. He is said to have completed the essentials on the train home and received the Nobel Prize for it in 1967. He led the theoretical division at Los Alamos, responsible for calculating the yield and the implosion physics of the plutonium bomb, and for checking Edward Teller's calculation that a detonation might ignite the atmosphere. After the war he became one of the most persistent scientific opponents of the arms race. He opposed the hydrogen bomb, worked on it when it was authorised, and afterwards campaigned for a test ban, advising Eisenhower and Kennedy and helping produce the 1963 Partial Test Ban Treaty. He opposed the Strategic Defense Initiative in the 1980s, argued against nuclear weapons laboratories continuing design work, and in 1995 wrote an open letter urging scientists to refuse to work on them. He published research past ninety and died in 2005.
- Lived: 1906 CE – 2005 CE
- Nationality: German
- Roles: physicist, scientist
