A physicist himself, Gino Segr writes about what scientists doand why they do itwith intimacy, clarity, and passion. In Faust in Copenhagen, he evokes the fleeting, magical moment when physicsand the worldwas about to lose its innocence forever. Known by physicists as the miracle year, 1932 saw the discovery of the neutron and antimatter, as well as the first artificially induced nuclear transmutations. However, while scientists celebrated these momentous discoverieswhich presaged the nuclear era and the emergence of big scienceduring a meeting at Niels Bohrs Copenhagen Institute, Europe was moving inexorably toward totalitarianism and war.