George Efstathiou was born in London in 1955. He earned a degree in Physics at Keble College, Oxford, in 1976, and received his Ph.D. in Astronomy from Durham University in 1979.
In the 1980s, Efstathiou was part of a collaboration—with Marc Davis, Carlos Frenk, and Simon White—that established the validity of the "cold dark matter" theory for the formation of galaxies and other cosmic structures, now the accepted interpretation in cosmology. In a classic series of papers, that collaboration—often called DEFW by their peers—used computer code developed by Efstathiou to simulate the growth of the universe and resolve disputes among theoretical models.
Efstathiou held two postdoctoral positions, first at the University of California, Berkeley, from 1979 to 1980, then at Cambridge from 1980 to 1984. He remained at the Institute of Astronomy at Cambridge until 1988, when he became the Savilian Professor of Astronomy at Oxford. In 1997 he returned to Cambridge, first as a professor of Astronomy in the Institute of Astronomy, then as the director of the Institute. Since 2008 he has been the director of the Kavli Institute of Cosmology at Cambridge.
Efstathiou’s research has often involved galaxy surveys that reveal the large-scale structure of the universe. While at both Cambridge and Oxford, he was one of the leaders of the APM (Automatic Plate Measuring) survey, the predecessor to the highly influential 2dF (2-degree Field) redshift survey of the Southern Hemisphere skies, for which Efstathiou also played a key role.
He was elected Fellow of the Royal Society in 1994. He has received the Maxwell Medal and Prize from the Institute of Physics and the Dannie Heineman Prize for Astrophysics from the American Institute of Physics and the American Astronomical Society, among numerous other prizes and awards. Efstathiou is currently a member of the European Space Agency Science Team of the Planck satellite, a space experiment that is making the most sensitive measurements yet of the Cosmic Microwave Background.