De Broglie-Bohm Theory, quo vadis?

Abstract

The purpose of this contribution is to examine the current state of the de Broglie-Bohm theory (dBB) in light of Bohm's vision as he explicitly set it out in his book Quantum theory (1961b). In particular, two programmes that differ in many crucial respects are currently being pursued. On the one hand, the Bohmian mechanics school, founded by Dürr Goldstein and Zanghì, considers the theory to be Galilean invariant, regards particles’ motion as determined by a nomological entity, the universal wave function, upholds the quantum equilibrium hypothesis and explains probabilities in terms of typicality. On the other hand, the Pilot-wave school advocated by Valentini considers the theory to be based on Aristotelian dynamics, regards the wave function as a physical field displaying a contingent nature, and explains quantum equilibrium as the result of a process of relaxation from quantum non-equilibrium. Looking at Bohm's 1961b work, it is clear that his intention was to construct a theory that was empirically different from standard quantum mechanics, so that it would be testable and falsifiable. Only this way could he defend dBB from the criticism that accused the theory of being 'metaphysical'. These methodological concerns about the falsifiability of the theory constitute, in my opinion, a strong reason for welcoming Valentini's programme as a valid alternative to standard quantum mechanics, even if it might turn out to be wrong. Indeed, only the programme of the Pilot-wave school aims to be falsifiable with respect to standard quantum mechanics and can in principle defend the empirical status of particle trajectories.