James S. Trefil is Clarence J. Robinson Professor of Physics at George Mason University in Fairfax, Virginia. His most recent book is Why Science (2007); he is also the author of The Nature of Science: An A-Z Guide to the Laws and Principles Governing Our Universe (Houghton Mifflin, 2003) and is a regular contributor to Smithsonian magazine. Address: 207F East Building, MS 1D6, George Mason University, Fairfax, VA 22030. Internet: jtrefil@gmu.edu