John Heilbron, professor of history and the vice chancellor, emeritus, University of California at Berkeley, is a senior research fellow at Worcester College, Oxford. His pertinent research interests centre on the history of atomic and quantum physics, especially the work of Max Planck and Niels Bohr. His most recent book, The Sun in the Church: Cathedrals as Solar Observatories, and his current writing focus on a long-run drama, the Roman Catholic Church's ongoing struggle to come to grips with Galileo.