Quantum theory : a philosopher's overview
Given its general motivation, " Quantum Theory: a Philosopher's Overview " by Salvator Cannavo is a very interesting book. The fundamental question is: Can quantum mechanics be an explanatory theory? In a nutshell, his answer is: " No ". I respectfully disagree. Before we enter into the merits of his case, let me describe the book. In Chapter 1 the author nicely reviews quantum theory. On the one hand, quantum mechanics (in the text " QT ") has had an unprecedented and overwhelming experimental success. On the other hand, however, quantum mechanics raises profound conceptual problems which are equally unprecedented. Since its discovery, the theory has generated a large philosophical debate about its ultimate intelligibility and its metaphysical implications. As Cannavo points out, " nothing of this glorious classical history, however, has been quite as stunning as the success of quantum theory – a success that has seemed utterly magical. [...] What quantum mechanics has not yet found itself is a universally accepted interpretation [...]. " (p.3). As the author discusses in Chapters 2 and 3, quantum physics presents most puzzling features, among which are the wave-like behavior of particles and vice versa, the macroscopic superpositions, the active role of a conscious observer, and nonlocality. " The natural response to the baffling aspects of quantum physics is the demand for an interpretation for QT " (p.39). In Chapter 4 Cannavo presents the Copenhagen interpretation and Bohm's hidden variable theory, while in Chapter 5 he discusses the many-worlds interpretations, the many-minds interpretations, decoherence theory, GRW theory, and quantum logic. The conclusion is that the situation is hopeless: all these interpretations are inadequate, for they all fall short of providing the sort of explanation an interpretation should give. After describing the distinction between explanatory and algorithmic theories (the former being able to make predictions and explanation, the latter just predictions), Cannavo shows in Chapter 6 how quantum theory has always been ultimately and irreducibly algorithmic, so that " […] the very long history of failed efforts at formulating a generally acceptable interpretation strongly suggests that the interpretational program is deeply impractical, if not utterly futile […] " (p. xii). We should recognize, Cannavo claims, that it is in the nature of quantum mechanics of not being able to explain phenomena. Physicists have developed new theories, like quantum electrodynamics, quantum field theory and string theory (to which Cannavo refers as " quantumized theories …