In 1939, six years before the atomic bombs were dropped on Hiroshima and Nagasaki, Austrian physicist Lise Meitner was explaining nuclear fission. As Otto Hahn's partner in his early neutron bombardment studies, Meitner was at first puzzled over some of the results, but didn't have time to dwell too long.
As Hitler came into his full power, the Jewish Meitner was forced to flee both Germany and, to some degree, her work. While she communicated with Hahn from her new base in Sweden, Meitner and her nephew, Otto Frisch, took a good look at the experimental data.
The pair realized that the nuclear fission they were witnessing involved something far more significant than a nucleus splitting into two: it also involved a loss of mass and a corresponding release of an enormous, (potentially atomic bomb-sized) amount of energy. For their work, Hahn received the Nobel prize and Meitner...did not. Whoops.
