Since their introduction in 1945, nuclear explosives have been the most feared of the weapons of mass destruction, in part because of their ability to cause enormous instantaneous devastation and of the persistent effects of the radiation they emit, unseen and undetectable by unaided human senses. The Manhattan Project cost the United States $2 billion in 1945 spending power and required the combined efforts of a continent-spanning industrial enterprise and a pool of scientists, many of whom had already been awarded the Nobel Prize and many more who would go on to become Nobel Laureates. This array of talent was needed in 1942 if there were to be any hope of completing a weapon during the Second World War. Because nuclear fission was discovered in Germany, which remained the home of many brilliant scientists, the United States perceived itself to be in a race to build an atomic bomb. When the Manhattan Project began far less than a microgram of plutonium had been made throughout the world, and plutonium chemistry could only be guessed at; the numbers of neutrons released on average in U-235 and Pu-239 fissions were unknown; the fission cross sections (probabilities that an interaction would occur) were equally unknown, as was the neutron absorption cross section of carbon. experiment. Although talented people are essential to the success of any nuclear weapons program, the fundamental physics, chemistry, and engineering involved are widely under-stood; no basic research is required to construct a nuclear weapon. Therefore, a nuclear weapons project begun in 1996 does not require the brilliant scientists who were needed for the Manhattan Project.