Russian-American physicists Gregory Breit (1899-1981, left) and George Gamow (1904-1968, right) and Italian-American physicist Enrico Fermi (1901-1954, centre) reading a journal article. Breit contributed to the theory of nuclear reactions and supervised the designs for the first atomic bomb. Fermi carried out fundamental theoretical and experimental work on nuclear and quantum physics and is best known for building the first nuclear reactor. Fermi won the 1938 Nobel Prize in Physics for his work on using neutrons to initiate nuclear reactions. Gamow showed that the Big Bang theory explained the observed proportions of hydrogen and helium in the universe. He also predicted the cosmic background radiation, which was detected in 1964. Photographed during the Fifth Washington Conference on Theoretical Physics, Washington DC, USA, in January 1939.