Otto Hahn and Lise Meitner , with their colleague
Fritz Strassman , bombarded uranium nuclei with slow speed neutrons.
Meitner, after fleeing the Nazis and working with Otto Frisch
, interpreted the Hahn-Strassman results to be 'nuclear fission,'
the term fission being borrowed from biology. They explained
what happened in the nucleus by reference to the liquid drop model:
"As the nucleus gets bigger, with more and more protons,
the protons are farther apart, and the repulsive strength grows
in comparison with the strong nuclear force, [and eventually]
just enough to tip the balance in favor of the repulsive forces
and split the nucleus" also calculated that vast amounts
of energy would be released by a sustained chain reaction.