Stephen M. Barr is a professor of Particle Physics at the Bartol Research Institute and the Department of Physics and Astronomy at the University of Delaware. His research interests include Elementary Particle Theory, Supersymmetric Grand Unified Theories, and Cosmology. He has authored over 120 physics papers in journals such as Physical Review D and Physics Today. He is also the author of the article on Grand Unified Theories for the Encyclopedia of Physics. He earned his Ph. D. in physics from Princeton University in 1978, and taught at the University of Pennsylvania, the University of Washington, and Brookhaven National Laboratory before joining the University of Delaware in 1987. He is regular contributor to the science and religion journal First Things, and sits on the journal’s editorial advisory board. Additionally, he is on the board of the Fellowship of Catholic Scholars. In 2003, he published Modern Physics and Ancient Faith on the University of Notre Dame Press. He lives in Newark, Delaware with his wife and five children.