Bethe attended the Gymnasium in Frankfurt from 1915 to 1924. He then studied at the University of Frankfurt for two years and at Munich for two and one half years where he earned his Ph.D. in theoretical physics in 1928 (Nobelprize.org). He was an Instructor in physics at Frankfurt for one semester and at Stuttgart for one semester. From 1929 to 1933 his headquarters were the University of Munich. In 1932-1933, he was Acting Assistant Professor at the University of Tubingen which he lost due to the advent of the Nazi regime in Germany. Bethe immigrated to England in October 1933 where he was a Lecturer at the University of Manchester from 1933-1934 and a fellowship at the University of Bristol in 1934. In February 1935, he was appointed Assistant Professor at Cornell University, Ithaca, New York, and then promoted to Professor in the summer of 1937. He worked at the Radiation Laboratory at the Massachusetts Institute of Technology, working on microwave radar, and then to the Los Alamos Scientific Laboratory which was assembling the first atomic bomb.
Bethe's main work is the theory of atomic nuclei. He developed a theory of the deuteron in 1934 which he extended in 1949. He studied the theory of nuclear reactions in 1935-1938, predicting many reaction cross sections. In connection with this work, he developed Bohr's theory of the compound nucleus in a more quantitative fashion (Nobelprize.org). His work on nuclear reactions led Bethe to the discovery of the reactions which supply the energy in the stars. The most important nuclear reaction in the brilliant stars is the carbon-nitrogen cycle, while the sun and fainter stars use mostly the proton-proton reaction. Bethe's main achievement in this connection was the exclusion of other possible nuclear reactions. The Nobel Prize was given for this work, as well as his work on nuclear reactions in general. Before his work on nuclear physics, Bethe's main was on atomic physics and collision theory. In collision theory, he developed a simple and powerful theory of inelastic collisions