In July 1938 a woman in her sixties sat on a train watching the German landscape go by, carrying two small suitcases of summer clothes, no valid passport, almost no money, and a diamond ring in her purse to bribe the guards if the SS pulled her off. Lise Meitner was leaving a world-class laboratory and thirty years of research behind, and taking the theoretical framework of the atomic age with her in her head. She had spent her whole life getting around locked doors. Public higher education was closed to women in the Vienna of her childhood, so she compressed advanced mathematics, physics, philosophy, and classical languages into two years of private tutoring, passed the external exam as one of only four women to do so, and became the second woman to earn a physics doctorate from the University of Vienna.

Berlin was worse before it was better. The head of the chemistry institute banned women from the laboratories, so while Otto Hahn worked upstairs, Meitner was put in a converted basement woodworking shop with its own outside entrance and no access to a restroom in the building. Cut off from the chemical methods Hahn used to separate elements, she invented a physical one, using the recoil of a decaying nucleus to collect daughter atoms on a charged plate. Her measurements of beta decay later showed electrons emerging with less energy than the laws of physics allowed, and her data was airtight enough to force Wolfgang Pauli to propose an invisible particle carrying the difference away. That particle was the neutrino.

• In 1938 Hahn found barium in bombarded uranium and could not explain it, so he wrote to her in exile asking for a “fantastic work around.”
• She and her nephew Otto Frisch worked it out on a scrap of paper on a tree trunk in the Swedish woods, treating the nucleus as an unstable liquid drop that stretches, necks, and snaps. They borrowed a word from cell biology and called it fission.
• She then noticed the fragments weighed less than the original atom, applied E=mc², and calculated exactly how much energy the missing mass became.
• The 1944 Nobel went to Hahn alone, and she refused to join the Manhattan Project, saying she would have nothing to do with the bomb. She later wrote to Hahn and Heisenberg condemning their accommodation of the Nazi regime, and called her own five years of staying in Germany a moral failure. Element 109 is meitnerium.