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Thursday, December 01, 2005

The First Nuclear Chain Reaction, December 2, 1942

Sorry about the audio gap at the end of the 'cast and for the double posting of the episode!

Today in 1942, the first man-made self-sustaining nuclear chain reaction was produced at the University of Chicago. The man directing the project was Enrico Fermi, an Italian Nobel-winning physicist who had only lived in the United States for four years. This accomplishment was the product of years of methodical research and, sometimes, lucky guesswork on the part of researchers in both the United States and Europe.

The properties of atomic particles and radioactivity were little understood in the first three decades of the 20th century. The Curies had shown it was possible to produce artificial radioactivity and James Chadwick had discovered the neutron (which is essential to creating a fission reaction), but it was Enrico Fermi who did the first work with neutrons and their effect on uranium. He was awarded the Nobel Prize in physics for his work in 1938 while still an Italian citizen. His ability to travel was restricted by the fascists due to his value as a national security resource, but he was given permission to travel to Sweden to accept the prize. He and his wife, who was Jewish, left Italy and never returned. They found a home at Columbia University in New York City, where Fermi was able to continue his research with Niels Bohr, the man who first postulated the model of the atom that most of us born in the second half of the 20th century learned about in high school. Bohr was also the first person to suggest that a nuclear chain reaction was possible.

It didn’t take long for Fermi, Bohr and their colleagues to realize that an uncontrolled chain reaction could be used to create a weapon of fearsome destructive capabilities. Along with Albert Einstein, the team drafted a letter to President Franklin Roosevelt expressing their opinion that the Nazis in Germany could, at some future time, develop an atomic bomb. A small amount of federal money was granted for more research in the area, but 1939 America was still reeling from the effects of the Great Depression and research money was scarce.

A little over two years later, all that changed. Once the United States entered World War Two in December, 1941, the venture that would be called the Manhattan Project received immediate and sustained funding. The goal was to research nuclear chain reactions and build an atomic weapon---before the Germans or Japanese did.

It was in this atmosphere of wartime urgency that Fermi and his team built an atomic pile on a squash court in the basement of Stagg Field at the University of Chicago. When the pile went critical and was then brought back to sub-criticality, a coded message was sent by telephone to one of the Manhattan Project’s leaders, James Conant: “The Italian navigator had landed in the New World…the natives are friendly.”

The world would never be the same.

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