Replication, the independent confirmation of experimental results and conclusions, is regarded as the "gold standard" in science. This book examines the question of successful or failed replications and demonstrates that that question is not always easy to answer. It presents clear examples of successful replications, the discoveries of the Higgs boson and of gravity waves. Failed replications include early experiments on the Fifth Force, a proposed modification of Newton's Law of universal gravitation, and the measurements of "G," the constant in that law.

Allan Franklin is professor of physics emeritus at the University of Colorado. He began his career as an experimental high-energy physicist and later changed his research area to history and philosophy of science, particularly on the roles of experiment. He has twice been chair of the Forum on the History of Physics of the American Physical Society and served two terms on the Executive Council of the Philosophy of Science Association. In 2016, Franklin received the Abraham Pais Prize for History of Physics from the American Physical Society. He is the author of eleven books including most recently Shifting Standards: Experiments in Particle Physics in the Twentieth Century and What Makes a Good Experiment?: Reasons and Roles in Science.