Editing De Broglie–Bohm theory (section)

== Occam's-razor criticism ==
Both [[Hugh Everett III]] and Bohm treated the wavefunction as a [[Scientific realism|physically real]] [[Field (physics)|field]]. Everett's [[many-worlds interpretation]] is an attempt to demonstrate that the wavefunction alone is sufficient to account for all our observations. When we see the particle detectors flash or hear the click of a [[Geiger counter]], Everett's theory interprets this as our ''wavefunction'' responding to changes in the detector's ''wavefunction'', which is responding in turn to the passage of another ''wavefunction'' (which we think of as a "particle", but is actually just another [[wave packet]]).<ref name=BrownWallace>{{cite journal | last1 = Brown | first1 = Harvey R. | author-link = Harvey Brown (philosopher) | last2 = Wallace | first2 = David | year = 2005 | title = Solving the measurement problem: de Broglie–Bohm loses out to Everett | url = http://philsci-archive.pitt.edu/archive/00001659/01/Cushing.pdf | journal = Foundations of Physics | volume = 35 | issue = 4| pages = 517–540 | doi=10.1007/s10701-004-2009-3|arxiv = quant-ph/0403094 |bibcode = 2005FoPh...35..517B | s2cid = 412240 }} Abstract: "The quantum theory of de Broglie and Bohm solves the measurement problem, but the hypothetical corpuscles play no role in the argument. The solution finds a more natural home in the Everett interpretation."</ref> No particle (in the Bohm sense of having a defined position and velocity) exists according to that theory. For this reason Everett sometimes referred to his own [[many-worlds interpretation|many-worlds approach]] as the "pure wave theory". Of Bohm's 1952 approach, Everett said:<ref>See section VI of Everett's dissertation [https://www.pbs.org/wgbh/nova/manyworlds/pdf/dissertation.pdf ''Theory of the Universal Wavefunction''], pp. 3–140 of [[Bryce Seligman DeWitt]], [[R. Neill Graham]], eds, ''The Many-Worlds Interpretation of Quantum Mechanics'', Princeton Series in Physics, [[Princeton University Press]] (1973), {{ISBN|0-691-08131-X}}.</ref>
{{cquote|Our main criticism of this view is on the grounds of simplicity – if one desires to hold the view that <math>\psi</math> is a real field, then the associated particle is superfluous, since, as we have endeavored to illustrate, the pure wave theory is itself satisfactory.}}

In the Everettian view, then, the Bohm particles are superfluous entities, similar to, and equally as unnecessary as, for example, the [[luminiferous ether]], which was found to be unnecessary in [[special relativity]]. This argument is sometimes called the "redundancy argument", since the superfluous particles are redundant in the sense of [[Occam's razor]].<ref>{{cite report |first=Craig |last=Callender |author-link=Craig Callender |url=http://philosophy.ucsd.edu/faculty/ccallender/The%20Redundancy%20Argument%20Against%20Bohmian%20Mechanics.doc |title=The Redundancy Argument Against Bohmian Mechanics |access-date=23 November 2009 |archive-url=https://web.archive.org/web/20100612191323/http://philosophy.ucsd.edu/faculty/ccallender/The%20Redundancy%20Argument%20Against%20Bohmian%20Mechanics.doc |archive-date=12 June 2010 |url-status=dead }}</ref>

According to [[Harvey Brown (philosopher)|Brown]] & Wallace,<ref name="BrownWallace" /> the de Broglie–Bohm particles play no role in the solution of the measurement problem. For these authors,<ref name=BrownWallace /> the "result assumption" (see above) is inconsistent with the view that there is no measurement problem in the predictable outcome (i.e. single-outcome) case. They also say<ref name=BrownWallace /> that a standard [[tacit assumption]] of de Broglie–Bohm theory (that an observer becomes aware of configurations of particles of ordinary objects by means of correlations between such configurations and the configuration of the particles in the observer's brain) is unreasonable. This conclusion has been challenged by [[Antony Valentini|Valentini]],<ref>{{Cite book|arxiv=0811.0810|last1=Valentini|first1=Antony|chapter=De Broglie-Bohm Pilot-Wave Theory: Many Worlds in Denial?|title=Many Worlds? Everett, Quantum Theory, and Reality |editor1-first=Simon |editor1-last=Saunders |editor2-first=Jon |editor2-last=Barrett |editor3-first=Adrian |editor3-last=Kent |publisher=Oxford University Press |volume=2010|issue=476|pages=476–509|year=2010 |bibcode=2008arXiv0811.0810V|doi=10.1093/acprof:oso/9780199560561.003.0019|isbn=978-0-19-956056-1}}</ref> who argues that the entirety of such objections arises from a failure to interpret de Broglie–Bohm theory on its own terms.

According to [[Peter R. Holland]], in a wider Hamiltonian framework, theories can be formulated in which particles ''do'' act back on the wave function.<ref>{{cite journal |first=Peter |last=Holland |title=Hamiltonian Theory of Wave and Particle in Quantum Mechanics I, II |journal=Nuovo Cimento B |volume=116 |pages=1043, 1143 |year=2001 |url=http://users.ox.ac.uk/~gree0579/index_files/NuovoCimento2.pdf |access-date=17 July 2011 |archive-url=https://web.archive.org/web/20111110140052/http://users.ox.ac.uk/~gree0579/index_files/NuovoCimento2.pdf |archive-date=10 November 2011 |url-status=dead }}</ref>