Editing De Broglie–Bohm theory (section)

==== Hidden variables ====
De Broglie–Bohm theory is often referred to as a "hidden-variable" theory. Bohm used this description in his original papers on the subject, writing: "From the point of view of the [[Copenhagen interpretation|usual interpretation]], these additional elements or parameters [permitting a detailed causal and continuous description of all processes] could be called 'hidden' variables." Bohm and Hiley later stated that they found Bohm's choice of the term "hidden variables" to be too restrictive. In particular, they argued that a particle is not actually hidden but rather "is what is most directly manifested in an observation [though] its properties cannot be observed with arbitrary precision (within the limits set by [[uncertainty principle]])".<ref>David Bohm, Basil Hiley: ''The Undivided Universe: An Ontological Interpretation of Quantum Theory'', edition published in the Taylor & Francis e-library 2009 (first edition Routledge, 1993), {{ISBN|0-203-98038-7}}, [https://books.google.com/books?id=vt9XKjc4WAQC&pg=PA2 p. 2].</ref> However, others nevertheless treat the term "hidden variable" as a suitable description.<ref>"While the testable predictions of Bohmian mechanics are isomorphic to standard Copenhagen quantum mechanics, its underlying hidden variables have to be, in principle, unobservable. If one could observe them, one would be able to take advantage of that and signal faster than light, which – according to the special theory of relativity – leads to physical temporal paradoxes." J. Kofler and A. Zeiliinger, "Quantum Information and Randomness", ''European Review'' (2010), Vol. 18, No. 4, 469–480.</ref>

Generalized particle trajectories can be extrapolated from numerous weak measurements on an ensemble of equally prepared systems, and such trajectories coincide with the de Broglie–Bohm trajectories. In particular, an experiment with two entangled photons, in which a set of Bohmian trajectories for one of the photons was determined using weak measurements and postselection, can be understood in terms of a nonlocal connection between that photon's trajectory and the other photon's polarization.<ref>{{cite journal | doi = 10.1126/science.1501466 | pmid=26989784 | pmc=4788483 | volume=2 | title=Experimental nonlocal and surreal Bohmian trajectories | year=2016 | journal=Sci Adv | page=e1501466 | last1 = Mahler | first1 = DH | last2 = Rozema | first2 = L | last3 = Fisher | first3 = K | last4 = Vermeyden | first4 = L | last5 = Resch | first5 = KJ | last6 = Wiseman | first6 = HM | last7 = Steinberg | first7 = A| issue=2 }}</ref><ref name="newscientist.com">Anil Ananthaswamy: [https://www.newscientist.com/article/2078251-quantum-weirdness-may-hide-an-orderly-reality-after-all/ Quantum weirdness may hide an orderly reality after all], newscientist.com, 19 February 2016.</ref> However, not only the De Broglie–Bohm interpretation, but also many other interpretations of quantum mechanics that do not include such trajectories are consistent with such experimental evidence.