Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

'Quantum Magic' Without Any 'Spooky Action at a Distance'

  1. Jun 25, 2011 #1
    Last edited by a moderator: Apr 26, 2017
  2. jcsd
  3. Jun 25, 2011 #2
    Here is the actual paper:
    http://arxiv.org/abs/1106.4481

    It uses the same joint probabilities Bell's theorem takes advantage of, only here it is used to show classical physics cannot even describe a single state quantum system using non-contextual hidden variable models.

    If single state quantum systems have this property it makes it difficult to attach nonlocal properties as any sort of mechanism for getting such results. In fact the nonlocality assumption appears to me to be predicated on some classical variable exceeding light speed to trigger a coincidence that was not already inherent in the individual particle properties. It is just as hard to define a FTL mechanism to trigger Bell's violations as it is to define a local mechanism.
     
  4. Jun 25, 2011 #3

    DrChinese

    User Avatar
    Science Advisor
    Gold Member

    I agree with what you are saying. Non-locality is no automatic solution to the puzzle. Because it begs the question: where are the rest of the non-local effects?

    Anyway, this is a cool experiment and one of a number of ongoing attacks on classical realism. All of which demonstrate that there is no meaning for non-commuting properties outside of the HUP.
     
  5. Jun 25, 2011 #4
    DrChinese,
    Given the measurability issues independent variables would pose, as you rightly pointed out in Hume’s Determinism Refuted, what would you say about the realism status of such variables if they only intermittently interacted stochastically? If our physical model is built from such stochastic interactions 'alone' the interaction rate in pre-quantized space would define our empirical variables as the energy equivalent of such interactions, defined by the mass energy relation. This would give empirical variables a relativistic signature [itex]\propto c^2[/itex] (rather than the classical [itex]v^2/2[/itex]) of the underlying realistic hidden variables, meaning the empirical properties cannot commute with the hidden variables (by means you articulated). Such stochastic interactions of many such hidden variables with a [itex]c^2[/itex] empirical signature would mimic both HUP and the Born rule at the empirical level if these are defined by mean stochastic interaction rates defined by the mean velocities of the underlying hidden variables. Would you call a model like this, which makes explicit use of the measurability issues you articulated for independent variables, realistic? Does ontological realism require the naked noncontextual variables of the model to have empirically accessible measurable properties themselves, or to produce such empirically accessible noncontextual variables, in spite of the impossibility you articulated of measuring such independent variable even if they existed?

    A number of authors use very similar devices under the name of "statistically complete variables" etc. I think the non-realism stance often short changes the work of these authors by demanding they produce exactly what you articulated quiet well why such cannot be empirically produced even if it existed. Yet the inability to empirically demonstrate a non-contextual variable does not prevent the modeling of such variables to produce the more usual contextual variables. The admission that on one hand such independent noncontextual variables would not be 'directly' measurable while on the other hand demanding realist to produce measurable non-contextual variables from their models to make their point sounds to me like having non-real pie and eating it to.

    Certainly such models fall short in the needed breadth of descriptive power. But I would much rather see skeptical rebuttals that went beyond, since the measurables are contextual there is no realism in your model. I would say the jury is still out on the realism issue, though certainly dead in the EPR conception of directly measurable non-contextual ontological entities. Such noncontextual entities would have to be required, both by first principles (you articulated) and empirical constraints, to produce purely contextual stochastic variables at the empirical level.

    So my main question here is which of these constraints actually rules out realistic ontological models when your own article hinges not on whether independent variables exist or not, but on there measurability status in the intervals between interactions, or anything other than a point-like stochastic fluctuation in the event of an interaction?
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: 'Quantum Magic' Without Any 'Spooky Action at a Distance'
Loading...