Hans C. Ohanian received his B.S. from the University of California, Berkeley, and his Ph.D. from Princeton University, where he worked with John A. Wheeler. He has taught at Rensselaer Polytechnic Institute, Union College, and the University of Vermont. He is the author of several textbooks spanning all undergraduate levels: Physics, Principles of Physics, Relativity: A Modern Introduction, Modern Physics, Principles of Quantum Mechanics, Classical Electrodynamics, and, with Remo Ruffini, Gravitation and Spacetime. He is also the author of dozens of articles dealing with gravitation, relativity, and quantum theory, including many articles on fundamental physics published in the American Journal of Physics, where he served as associate editor for some years. He lives in Vermont.