The return of Bohm's pilot wave theory

Discussion in 'Physics & Math' started by Magical Realist, Dec 8, 2016.

  1. Magical Realist Valued Senior Member

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    I guess on the "severely unexplained phenomena" scale, surreal is higher up than just magical. At least with magically collapsed wavefunctions there is SOME predictability. Surreal is well...just crazy! What do you think about this?

    "Of the many counterintuitive features of quantum mechanics, perhaps the most challenging to our notions of common sense is that particles do not have locations until they are observed. This is exactly what the standard view of quantum mechanics, often called the Copenhagen interpretation, asks us to believe. Instead of the clear-cut positions and movements of Newtonian physics, we have a cloud of probabilities described by a mathematical structure known as a wave function. The wave function, meanwhile, evolves over time, its evolution governed by precise rules codified in something called the Schrödinger equation. The mathematics are clear enough; the actual whereabouts of particles, less so. Until a particle is observed, an act that causes the wave function to “collapse,” we can say nothing about its location. Albert Einstein, among others, objected to this idea. As his biographer Abraham Pais wrote: “We often discussed his notions on objective reality. I recall that during one walk Einstein suddenly stopped, turned to me and asked whether I really believed that the moon exists only when I look at it.”

    But there’s another view — one that’s been around for almost a century — in which particles really do have precise positions at all times. This alternative view, known as pilot-wave theory or Bohmian mechanics, never became as popular as the Copenhagen view, in part because Bohmian mechanics implies that the world must be strange in other ways. In particular, a 1992 study claimed to crystalize certain bizarre consequences of Bohmian mechanics and in doing so deal it a fatal conceptual blow. The authors of that paper concluded that a particle following the laws of Bohmian mechanics would end up taking a trajectory that was so unphysical — even by the warped standards of quantum theory — that they described it as “surreal.”

    Nearly a quarter-century later, a group of scientists has carried out an experiment in a Toronto laboratory that aims to test this idea. And if their results, first reported earlier this year, hold up to scrutiny, the Bohmian view of quantum mechanics — less fuzzy but in some ways more strange than the traditional view — may be poised for a comeback."----------https://www.quantamagazine.org/20160517-...l-support/
     
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  3. Confused2 Registered Senior Member

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    I've never seen this as an objection to Broglie-Bohm (BB) so I'll post it here and see what happens.

    The BB is a two pass theory - first you set up your exploratory wavefunction and then you run your particle through it, having done that (whatever the result) you remove your exploratory (evanescent) wavefunction (which fills the Universe) by means undefined. Copenhagen just lets rip on a single pass, says "Job done" when any interaction occurs and automatically removes the wavefunction (which may fill all space) all in one swipe. Either way the removal of the wavefunction is the mother of all clean up jobs. One pass faster than two passes so my money goes on one pass.
     
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  5. Schmelzer Valued Senior Member

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    There is no removal of the wave function in dBB theory. It is always there. Nobody has to clean it up. It exists together with the particle itself, which also always exists.
     
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  7. Confused2 Registered Senior Member

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    Now I really don't like it.
     
  8. rpenner Fully Wired Staff Member

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    In my opinion, this resolves nothing. Indeed, in the two slit experiment was not the measurement of Bohmian quantum particle trajectories but the weak measurement of the momentum operator of the electromagnetic field. Weak measurement is an exciting new physics development not well covered in standard textbooks, but is governed by universal quantum rules which have the same predicted observables (as far as I can tell) in all quantum interpretations.

    MR's article: https://www.quantamagazine.org/20160517-pilot-wave-theory-gains-experimental-support/
    The scientific paper it was based on: http://advances.sciencemag.org/content/2/2/e1501466 (Open Access)
    Comment on the above: https://arxiv.org/abs/1611.06510

    On Weak Measurement:
    https://en.wikipedia.org/wiki/Weak_measurement
    http://people.isy.liu.se/en/icg/jalar/kurser/QF/assignments/Aharonov1988.pdf
    http://repository.ias.ac.in/51062/1/133-pub.pdf
     

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