Hungarian physicist Leó Szilárd was stuck at a red light on Southampton Row in Bloomsbury, London, when his mind started wandering. As he waited, he pondered a conversation he had with Ernest Rutherford, who dismissed the idea of nuclear energy. Szilárd wondered, what if you could split atoms to release more neutrons, leading to a chain reaction? His eureka moment would change the course of history, paving the way for nuclear power and atomic bombs. Little did he know, his idea would soon set off a chain reaction of its own, sparking a global nuclear arms race.