Launched in 1942, the Manhattan Project was a well-funded, secret effort by the United States, the United Kingdom, and Canada to develop an atomic bomb before the Nazis. The results--the bombs named "Little Boy" and "Fat Man"--were dropped on Hiroshima and Nagasaki in August of 1945. A vast state within a state, the Manhattan Project employed 130,000 people and cost the United States and its allies 2 billion dollars, but its contribution to science...