In the spring of 1939, Albert Einstein, mulling over recent advances in nuclear physics in his study at Princeton University, realized that every step required to achieve the creation of an unfathomably powerful weapon had been individually completed. The isolation of uranium, nuclear fission, the chain reaction, the buffering of the reaction, and its controlled release in a chamber had all fallen into place. All that was required was sequence: if you strung these reactions together in order, you obtained an atomic bomb.
