THE MANHATTEN PROJECT During World War II when the war was about to break out in Europe, the United States first started looking at building an atomic bomb but the Germans were already two years ahead of the Americans. A nuclear bomb at the time would provide definite power to end the war. Albert Einstein was concerned that the Germans would develop and use nuclear weapons first. That prompted Einstein to write his letter to …showed first 75 words of 822 total…

…showed last 75 words of 822 total…flattered into a sheet will not. The flat piece has a very large surface area and so an enormous number of neutrons are able to escape from the uranium into the air. These neutrons do not cause further fission reactions and so the chain reaction will die out. In the spherical piece of uranium, the surface area is much smaller and a greater proportion of neutrons remain in the uranium to sustain the chain reaction.