Bradley E. Schaefer is Distinguished Professor and Alumni Professor in the Department of Physics and Astronomy at Louisiana State University (LSU). He earned his undergraduate and Ph.D. degrees in Physics, both from the Massachusetts Institute of Technology. He was a research astrophysicist at NASA's Goddard Space Flight Center and a professor at Yale University, before joining LSU, where his teaching has earned him the Alumni Professorship and the Distinguished Faculty Award. He has over 200 publications in refereed journals. Starting in the mid-1990s, Professor Schaefer joined the Supernova Cosmology Project, led by Saul Perlmutter. This group found that the expansion rate of the universe is accelerating, propelled by an unknown dark energy. As one of the discoverers of dark energy, Professor Schaefer received a share of the Gruber Cosmology Prize in 2007 as well as a share of the Breakthrough Prize in Fundamental Physics in 2015. In 2011, Perlmutter was a co-winner of the Nobel Prize in Physics for leading this work. In addition to his cosmology research, Professor Schaefer has written numerous articles on the history of astronomy, including frequent pieces for Sky & Telescope. He is on the editorial boards of both Archaeoastronomy and the Journal for the History of Astronomy, and he has served on the editorial board for Culture and Cosmos.