There are currently more than 12,000 nuclear warheads in existence around the world, despite attempts at disarmament and international treaties, according to this 80-year anniversary feature by WIRED Italia, which looks at the history of the atomic bomb and how they work.
It was in 1933 when Leo Szilard, a Hungarian scientist who had fled Nazi Germany, came up with the idea that if an atom could be hit with a neutron and fragment into two or more neutrons, it would initiate a self-sustaining nuclear reaction.
Italian physicist Enrico Fermi discovered in 1938 that uranium could achieve this and the secret Manhattan Project was set up in 1940 to develop nuclear weapons, headed by Arthur Compton and including Fermi, Szilard and theoretical physicist Julius Robert Oppenheimer.
The first nuclear reaction built by humans was conducted undercover of the University of Chicago’s football field in 1942 and in 1943 Oppenheimer became project manager at Los Alamos laboratories in New Mexico, where the first atomic device in history was designed and built.
