On August 9, 1945, a second atomic bomb detonated over Nagasaki. The physicist who had theoretically explained nuclear fission in 1938 — who had done the mathematics that made the Manhattan Project possible — was living in Swedish exile, having fled Nazi Germany the year before, having refused to participate in weapons research, having just learned that the bombs had been dropped.

Lise Meitner was born on November 7, 1878, in Vienna. She studied physics when women were not admitted to university, obtaining special permission to attend lectures at the University of Vienna, then earning her doctorate — one of the first women to do so in physics — from that institution in 1905. She moved to Berlin, where she worked with Otto Hahn for thirty years. For the first four years, she was not allowed in the main building of his laboratory because the director forbade women from the premises. She worked in a converted carpenter's shop in the basement.

By 1917, Meitner and Hahn had discovered protactinium together. By the 1930s, they were working on uranium bombardment experiments. In December 1938, Hahn and Strassmann split the uranium nucleus. They sent the results to Meitner, now in Stockholm, because they didn't understand what they had found. Meitner and her nephew Otto Frisch worked out the explanation during a walk in the snow: the nucleus had split, releasing enormous energy. Meitner named it nuclear fission.

In 1944, the Nobel Prize in Chemistry was awarded to Otto Hahn alone for the discovery of fission. Meitner's name was not on it.

She refused to work on the Manhattan Project. When a journalist described her as the "Jewish mother of the bomb" in 1946, she wrote letters of correction for months. She was not the mother of the bomb. She had done the physics. The bomb was what other people did with it.

She received the Enrico Fermi Award in 1966, three years before she died. Element 109 is named meitnerium. She was nominated for the Nobel forty-eight times.