The Alsatian-born American theoretical physicist Hans Albrecht Bethe , prolific and creative contributor to several vital fields of nuclear physics, discovered the mechanism of energy production by stars (including the sun).

Hans Bethe was born in Strasbourg, Alsace-Lorraine— (now part of France)—on July 2, 1906, to Albrecht Theodore Bethe, a physiologist, and Anna Kuhn Bethe. At the age of 22 he earned his doctorate at the University of Munich and was given an assistantship at the Institute of Theoretical Physics of the University of Frankfurt. After a year he transferred to the Technische Hochschule in Stuttgart and then for three years was privatdozent —unsalaried lecturer—in physics at the University of Tubingen. He worked at Cambridge University and in Rome in 1930-1931 and then returned to Tubingen as an assistant professor.

After Hitler came to power, Bethe fled first to England and then to the United States, where Cornell University welcomed him. At age 31 he was elevated to the post of Wendell Anderson professor of physics. In 1939 he married Rose Ewald, the daughter of Paul Peter Ewald, a professor of physics in Munich. They had a son and a daughter.

In 1939 Bethe published a paper, "Energy Production in Stars," in which he advanced a theory of stellar fuel. He discovered that, by a series of transformations, carbon, acting as a catalyst, changes four atoms of hydrogen into an atom of helium of atomic weight four. During these transformations the carbon is rejuvenated and there is a very small loss of mass which is converted into the enormous amount of energy which stokes the stars. For this achievement as well as for his many important contributions to the theory of nuclear reactions, Bethe was awarded the Nobel Prize in physics in 1967.

Bethe published the first theory of electron-positron pair creation and an improved theory of how charged particles interact