Bruno Rossi (1905–1993), one of the giants of 20th-century physics, was a pioneer in cosmic-ray physics and virtually every other aspect of high-energy astrophysics. His scientific career began at the University of Florence in 1928 and continued at the University of Padua until 1938, when the Fascist anti-Semitic racial laws were passed in Italy. He was dismissed from his professorship and was forced to emigrate, as described in unpublished letters and documents that display the international character of physics and physicists. His young bride Nora Lombroso, his love of physics, and the solidarity of the physics community gave him the courage to begin a new life in Copenhagen, Manchester, and in the New World at the University of Chicago, Cornell University, Los Alamos, and after the Second World War at the Massachusetts Institute of Technology where he became the center of a worldwide research network.