At the Heart of the Atom

Did Physicists Recognize the Military Uses of Fission?

How was the plutonium bomb used?

The plutonium bomb, named “Fat Man” for its shape, was dropped on the city of Nagasaki, Japan, on August 9, 1945. It contained 6.4 kilograms (14 pounds) of plutonium-239. About 20% fissioned, and less than one gram was converted into energy with the equivalent of 21,000 tons of TNT. As many as 80,000 people were killed in the attack.


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