“The Gadget” (1945). The world’s first atomic bomb, for security reasons nicknamed “the Gadget” by the Los Alamos National Laboratory scientists who built it, was of the same design as the “Fat Man” bomb later detonated over Nagasaki, Japan, on August 9, 1945. Based on the implosion principle, with its plutonium sphere uniformly crushed into a reacting critical mass by an array of explosive charges on its outer surface, the device yielded the explosive energy of 21 kilotons of TNT when it was detonated in a test (code-named “Trinity”) on July 16, 1945. This full-scale replica is on display at the National Museum of Nuclear Science and History in Albuquerque, New Mexico.