Julian Barbour. Composite image of Julian Barbour (born 1937), English theorist on astrophysics and time, in conversation with himself. After studying mathematics at Cambridge University, England, he commenced a PhD on astrophysics in Munich. In 1968 he completed a PhD on the origins of relativity in Cologne. Barbour argues that time is an artefact born of the observation of change. He theorises that the quantum universe is static, existing as a set of states independent of time, governed only by their probability. Our notion of time arises from observation of these states. His published works include Absolute or Relative Motion (1989) and The End of Time (1999). Photographed in 2000.