Otto Hahn and Fritz Strassmann, at the Kaiser Wilhelm Institute for Chemistry in Berlin, bombard uranium with neutrons in December 1938 and detect, through careful chemical analysis, the presence of barium among the resulting products — a puzzling finding, since barium has roughly half the atomic mass of uranium, and no nuclear process known until then produced elements so different from the original via neutron bombardment. Hahn communicates the experimental results by letter to Lise Meitner, an Austrian physicist who had co-directed the research for years before being forced to flee to Sweden after the German annexation of Austria in 1938 due to her Jewish ancestry. Meitner, together with her nephew Otto Frisch, correctly interprets within days that the uranium nucleus has literally split into two lighter nuclei — barium and krypton — releasing an amount of energy consistent with Einstein's formula E=mc², and coins the term "fission" by analogy with biological cell division. The discovery, published by Hahn and Strassmann in January 1939 and theoretically explained by Meitner and Frisch that same month, immediately triggers the scientific and military race toward nuclear energy that would culminate, six years later, in the Manhattan Project.