Dr. John Mack died Tuesday in London, the victim of an auto accident. Dr. Mack, a Harvard professor, wrote A Prince of Our Disorder, a Pulitzer Prize-winning biography of T.E. Lawrence, or Lawrence of Arabia. Years later, he did controversial research on people who claimed they had been abducted by aliens. NPR's Robert Siegel speaks with a friend and colleague of Dr. Mack, Dr. Robert Jay Lifton of the Harvard Medical School.