ABSTRACT
Of the many achievements of 20th-century science, perhaps the most fundamental is quantum mechanics. Devised by a small group of highly gifted European physicists, the science of the atom entails profound and controversial transformations in our understanding of nature. Matter can be waves or particles, depending on how one observes them, and cause and effect are no longer closely related. This interpretation of quantum mechanics—prescriptions for how and when it is to be used and what it tells us about the physical world—was developed in 1927 in Copenhagen. Because of the propagation by its originators and the astonishing success of its practitioners, the Copenhagen interpretation had by the 1930s attained the preeminence it enjoys today. But an interpretation is only that. Its origins, defense and acceptance can be in important respects the products of historical circumstance and personal preference as well as of scientific validity.
