Actual Physics, Observation, and Quantum Theory

Since its inception, quantum theory has been the subject of fierce interpretive controversy, which persists to this day. Disputed topics include the basic ontology and dynamics of the theory, the role (if any) of measurement, the meaning of probability, and the issue of non-locality. But there is yet another problem that has been largely ignored: how the theory makes contact with observational data. The problem is endemic to physics, and was discussed by Einstein in several places. In this essay, I discuss Einstein’s general approach, how it applied to some quantum-mechanical phenomena, and why a central aspect of the solution might lead to novel and important new predictions.