 Besides the  guiding equation,  there are other velocity formulas with nice properties, including Galilean symmetry, and yielding theories that are empirically equivalent to orthodox quantum theory—and to Bohmian mechanics (Deotto &amp; Ghirardi 1998). The Bohmian choice is arguably the simplest. Moreover, Wiseman (2007) has shown that it is the Bohmian velocity formula, given by the  guiding equation,  that, according to orthodox quantum theory, would be found in a “weak measurement” of the velocity of a particle. (Marian, Zanghì, and Oriols 2016 have recently proposed an explicit procedure for performing such a measurement.) And, somewhat paradoxically, it can be shown (Dürr, Goldstein, &amp; Zanghì 2009) that according to Bohmian mechanics such a measurement is indeed a genuine measurement of the particle’s velocity—despite the existence of empirically equivalent velocity formulas! Similarly, weak measurements could be used to measure trajectories. In fact, quite recently Kocsis et al. (2011) have used weak measurements to reconstruct the trajectories for single photons “as they undergo two-slit interference”, finding “those predicted in the Bohm-de Broglie interpretation of quantum mechanics”. And Mahler et al. 2016 have experimentally found, using weak measurements, “Bohmian trajectories” for entangled photons, illustrating quantum nonlocality and the phenomenon of “surreal Bohmian trajectories”. 