Category: Physics

Passon’s defense

“Why isn’t every physicist a Bohmian?” by Oliver Passon [arXiv:quant-ph/0412119v2]

Admitting interest in the de Broglie-Bohm theory to a fellow physicist might elicit at most a raised eyebrow or a disbelieving smile.  But most physicists don’t know enough about dB-B to formulate objections.  But if the Bohmian or Bohm-curious physicist finds themselves in the position of having to defend Bohmian mechanics to the skeptic rooted in the heterodox interpretation of quantum mechanics, Passon’s article is a decent cheat sheet.

In this brief paper, Passon lists and discusses the main objections to dB-B theory and answers them.  Passon divides his defense of the Bohmian view into two parts: meta-theoretical and “theory-immanent.”  The meta-theoretical objections typically miscast Bohmian theory as being of only philosophical interest.  The theory-immanent objections focus on the perceived shortcomings of the physics of the Bohmian picture.  One theory-immanent objection being that of the once-supposed “surrealistic” particle trajectories in Bohmian mechanics.  I first learn about these “surrealistic” trajectories when I was in graduate school when Marlan Scully came to our department to talk about his quantum “which-way detectors.”  It’s a fascinating subject which has been thoroughly analyzed and is now well-understood.  But at the time, it appeared that Scully had put the bullet into Bohm’s theory.

Passon’s treatment suffers from brevity.  However, he has provided copious (94 to be exact) references to fuller expositions on the points touched on in his article.  The title, while provocative, is somewhat misleading.  I don’t get the impression that Passon is trying to show the strengths of the Bohmian picture, and it appears he’s content with just answering the various objections.  The interested reader who wants to be convinced that Bohmian mechanics is the correct picture will have to read the articles of Detlef Dürr, Sheldon Goldstein, and Nino Zanghì.

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Bohm in Exile

“Science and exile: David Bohm, the hot times of the Cold War, and his struggle for a new interpretation of quantum mechanics” by Olival Freire Jr. [arXiv:physics/0508184v1]

Bohm’s causal interpretation was not well received when he proposed it in the foundational 1952 manuscripts with appeared in the Physical Review.  Freire examines some of the reasons why Bohm’s theory met with such opposition.  As a result of the McCarthy “witch hunt” Bohm left the US in 1951 for Brazil.  Freire argues that neither McCarthyism nor Bohm’s political exile were major factors in the rejection of his theory.  Bohm’s theory was not popular because of bias do the “culture of physics.”  And to no small degree due to the active opposition of Léon Rosenfeld who took on the task of combating the causal interpretation as a personal crusade.

Freire also discusses attempts to fit the causal interpretation into the program of dialectical materialism.

The information presented in this 55 page paper is of historical interest. Freire shows just how significant Bohm’s contribution to physics is and in the closing paragraph characterizes the role of Bohm and John Bell as analogous to Kepler and Newton (respectively).  Bell’s inequalities together with Aspect’s experiments demonstrating that nature is fundamentally nonlocal is a major advance in physics.  Bohm’s theory set the stage for this breakthrough.