Leó Szilárd was a Hungarian physicist who, during a mundane moment waiting to cross a street in Bloomsbury, London, began to ponder the possibilities of nuclear fission—an idea that had been gaining traction in scientific circles. As he stood at the traffic light, Szilárd contemplated how uranium atoms, when bombarded with neutrons, could split and release a vast amount of energy. This reflection led him to visualize a scenario where the released neutrons could trigger further fissions, creating a chain reaction. This moment of inspiration occurred amidst a backdrop of rising interest in atomic physics, particularly after various advances in understanding radioactivity and atomic structure by contemporaries like Ernest Rutherford and Niels Bohr.Szilárd's realization would lay the groundwork for the development of nuclear reactors and ultimately the atomic bomb. Recognizing the potential implications of his idea, he began to discuss it with fellow scientists, including colleagues such as Albert Einstein. In 1939, Szilárd and Einstein would famously draft a letter to U.S. President Franklin D. Roosevelt, urging the United States to initiate its own atomic research, thereby marking the inception of the Manhattan Project. Szilárd's insight during this seemingly ordinary moment had a profound impact on the scientific community and the course of World War II, fundamentally reshaping energy policy and international relations in the decades to follow.