Early in 1940, and in the face of Hitler’s European conquests, Albert Einstein convinced President Franklin Roosevelt to fund the creation of a new weapon. These notebook pages from the Manhattan Project—code name for the atomic bomb—reveal the first successful controlled and self-sustaining nuclear chain reaction. At the bottom of the notebook, one scientist comments, “We’re cookin!” Not only did this experimental project usher in a new age of weaponry, but it also began an era where nuclear power could be harnessed and used for energy. America first used nuclear weapons to devastate the Japanese cities of Hiroshima and Nagasaki. The power of the bomb reverberated throughout the world and created fears that fueled the Cold War for nearly five decades.