nuclear chain reactor

Enrico Fermi helped create the world’s first Self-Sustaining Nuclear Chain Reactor. It was a big success but had to be kept secret. In-case the Germans got any funny ideas about bombs being made.

Even his wife, Laura Fermi, was oblivious although she did notice her husband being bombarded with congratulations. She wanted to know why, but no one would give her a reason. A coworker finally whispered to her: 
“He has sunk a Japanese admiral!" 
When Laura Fermi asked her husband if that was true, he replied,
"Did I?" 
The obvious next question was asked: 
"So you didn’t sink a Japanese admiral?" 
Without changing his sincere expression, Fermi said, 
"Didn’t I?”