The English-born American physicist Freeman J. Dyson is widely recognized for his contributions to quantum electrodynamics and the theory of interacting electrons and photons — and perhaps even better known for his creative speculations on subjects ranging from space travel to extraterrestrial civilizations. An engaging author, widely sought-after lecturer, and an unusually conscientious citizen of the world, he has been for more than half a century a persistent scientific and political gadfly in the most positive sense of the word. Born in London in 1923, he went up to Cambridge University from Winchester College, and after civilian service doing operations research at the headquarters of the RAF Bomber Command during World War II, he took his B.A. in mathematics at Cambridge in 1945. A fellow at Trinity College, Cambridge, in 1946-47, he was a Commonwealth Fellow at Cornell University and the Institute for Advanced Study in Princeton for the next two years. After another two years as a research fellow at the University of Birmingham, he became a professor of physics at Cornell in 1951. Two years later, he returned to the Institute for Advanced Study where he was a professor of physics until 1994 when he became professor emeritus. He has been a visiting professor at Yeshiva University and the Max Planck Institute for Physics and Astrophysics. During the late 1950s, Professor Dyson helped design the nuclear reactor, Triga, and the Orion space ship at General Atomic Laboratories in San Diego, California. He originated the idea for what is known as the “Dyson sphere,” a hypothetical shell of artificial material that an advanced civilization of intelligent beings with an expanding population might build around a parent star. The “colonists,” he suggested, would be able to capture almost all of the energy released by the star in the form of electromagnetic radiation, which would then be re-radiated as infrared radiation making the star visible to infrared telescopes. Professor Dyson served as chair of the Federation of American Scientists in 1962-63 and was a member of the National Research Commission on Life Science from 1989 to 1991. The recipient of honorary degrees from seventeen American and European colleges and universities, including Princeton, Oxford, and the Federal Institute of Technology (ETH) in Zurich, he is a Fellow of the Royal Society and a member of the U.S. National Academy of Sciences, as well as a foreign associate of the French Academy of Sciences and an honorary fellow of Trinity College, Cambridge. Among his other honors are a dozen major science prizes, including the Enrico Fermi Award of the U. S. Department of Energy. In 2000, he was awarded the Templeton Prize. The author of nearly 300 scientific papers, he also has been a frequent contributor to The New Yorker, The Atlantic Monthly, and The New York Review of Books. His capacity for luminous exploration of the intellectual challenges and moral dilemmas of modern science first came to the attention of the general public in 1979 when the Alfred P. Sloan Foundation commissioned him to write a memoir of his life in science, Disturbing the Universe. He won the National Book Critics Circle Award for Non-Fiction in 1984 for his powerful plea for international control of the world’s nuclear arsenal, Weapons and Hope. In his probing Origins of Life (1986), he suggested careful scrutiny of the notion that life began twice. Infinite in All Directions (1988), an explanation of what past and recent scientific theories tell us about the beginning of the universe, its present state, and its likely destiny, won the Phi Beta Kappa Award in Science. His latest books are Imagined Worlds (1997), The Scientist as Rebel (2006), and A Many Colored Glass: Reflections on the Place of Life in the Universe, which was published by the University of Virginia Press in 2007 and recounts the myriad ways the universe presents itself to us and how, as observers and participants in its processes, we respond to it.