Victor Weisskopf, a renowned theoretical physicist who made important contributions to quantum mechanics in Germany in the 1920s and in the U.S. in the 1970s, died in Cambridge, Massachusetts, USA, on 21 April. Weisskopf was a member of the first ICTP Scientific Council. Born in Vienna, then the capital of the Austrian-Hungarian empire, Weisskopf served as a group leader of the Manhattan Project in the U.S. during World War II. He witnessed the world's first atomic explosion in Alamogordo, New Mexico, in 1945. In the early 1960s, he served as Director General of CERN (the European Organization for Nuclear Research), based in Geneva, Switzerland.