Joseph Rotblat: Moral Dilemmas and the Manhattan Project

John Fitzgerald Kennedy famously said, “One man can make a difference and every man should try.”1 Joseph Rotblat (1908–2005) was the quintessence of Kennedy’s conviction. He was the only scientist who left Los Alamos after it transpired that the atomic bomb being developed there was intended for use against adversaries other than Nazi Germany. I explore Rotblat’s early research in Warsaw and Liverpool, which established his reputation as a highly capable experimental physicist, and which led him to join the Manhattan Project at Los Alamos in 1944. I examine his motivation for resigning from the project in 1945, and the unwillingness of his fellow scientists to follow suit, which draws attention to the continuing discourse on the responsibility of scientists for the consequences of their research.