had been cleared of any potential wrongdoing at a subsequent hearing that year, he was denied a prerequisite security clearance for a Japanese physics conference in 1952, precipitating his refusal to join a Teller-chaired Department of Defense advisory group. While he reluctantly signed the loyalty oath stipulated by the Levering Act for Berkeley personnel in 1950, growing antagonism between Oppenheimer and the more conservative Lawrence eventually spurred his departure. In 1951, he became a professor of physics at Columbia University at the behest of Manhattan Project colleague I. I. Rabi. He served as chair of the department from 1975 until his retirement as professor emeritus in 1978. At Columbia, Serber served as doctoral advisor to future Nobelist Leon Cooper. He also collaborated with Abraham Pais on meson studies and developed the Serber-Dancoff method, a refined technique for analyzing strong coupling. He also consulted numerous labs, businesses, and commissions, including Brookhaven National Laboratory (where he worked one day a week during the academic year and occasional summers for twenty years) and Fermilab, as a specialist in the proton–proton chain reaction and the focusing properties of particle accelerators. Although largely bereft of any ideology, he refused to join the Defense Department-affiliated JASON consulting group because of his previous clearance issues and opposition to the Vietnam War. After being diagnosed with Parkinson’s disease, Charlotte Serber suffered from depression and took her own life with an overdose of sleeping pills on May 22, 1967. In the years thereafter, he began a relationship with the widowed Kitty Oppenheimer. She talked him into buying a yawl, which they sailed from New York to Grenada. In 1972, they purchased a ketch, with the intention of sailing through the Panama Canal and to Japan via the Galapagos Islands and Tahiti during Serber's sabbatical. They set out, but Kitty became ill, and was taken to Gorgas Hospital, where she died of an embolism on October 27, 1972. Serber and Toni Oppenheimer scattered her cremains near the Oppenheimers' longtime vacation home in Saint John, U.S. Virgin Islands, which he continued to use. Following his retirement, he married Fiona St. Clair, a fabric designer from Saint Thomas, U.S. Virgin Islands, in 1979. He adopted her son Zachariah, and they had another son, William, in November 1980. He served as president of the American Physical Society in 1971. A year later, Serber was awarded the J. Robert Oppenheimer Memorial Prize. Serber appears