Quantum Mysteries for Anyone

N. David Mermin

Frank Lad

I provide a critical reassessment of David Mermin’s influential and misleading parable, “Quantum Mysteries for Anyone”, identifying its errors and resolving them with a complete analysis of the quantum experiment it is meant to portray. Accessible to popular readership and requiring no knowledge of quantum physics at all, his exposition describes the curious behaviour of a machine that is designed to parody the empirical results of quantum experiments monitoring the spins of a pair of electrons under various conditions. The mysteries are said to unfold from contradictory results produced by a signal process that is proposed to explain them. I find that these results derive from a mathematical error of neglect, coupled with a confusion of two distinct types of experiments under consideration. One of these, a gedankenexperiment, provides the context in which the fabled defiance of Bell’s inequality is thought to emerge. The errors are corrected by the recognition of functional relations embedded within the experimental conditions that have been long unnoticed. A Monte Carlo simulation of results in accord with the actual abstemious claims of quantum theory supports probability values that Mermin decries as unwarranted. However, the distribution it suggests is not definitive, in accord with the expressed agnostic position of quantum theory regarding measurements that cannot be executed. Bounding quantum probabilities are computed for the results of the gedankenexperiment relevant to Bell’s inequality which inspired the parable. The problem is embedded in a 3 × 3 design of Stern-Gerlach magnet orientations at two observation stations. Computational resolution on the basis of Bruno de Finetti’s fundamental theorem of probability requires the evaluation of a battery of three paired linear programming problems. Though technicalities are ornate, the message is clear. There are no mysteries of quantum mechanics that derive from mistaken understandings of Bell’s inequality… for anyone.

Philippe Grangier

Joseph M. Renes

N. David Mermin

A simple device is described, based on a version of Bell’s inequality, whose operation directly demonstrates some of the most peculiar behavior to be found in the atomic world. To understand the design of the device one has to know some physics, but the extraordinary implications of its behavior should be evident to anyone. Except for a preface and appendix for physicists, the paper is addressed to the general reader.

N. David Mermin

Tentative d'exposition de problemes conceptuels souleves par la mecanique quantique sans recours a des connaissances physico-mathematiques prealables du lecteur, par description d'un dispositif physique imagine par l'A. de maniere a formuler le probleme EPR et celui de Bell.