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Non locality of quantum mechanics

  1. Aug 23, 2013 #1
    Can we have a local hidden variable theory explanation for Bells theorem?

    The outcomes of the mesurement (measuring the electron spin of an entangled electron pair as Red or Green) can be random initially without any correlation at all.

    But by the time we compare the results of the two measurements, our memories could be modified such that we remember having made a particular of measurements which had correlation.

    Would not such a explanation get rid of the non locality of quantum mechanics?
    will have to give up our idea of a consistent memory for this.
  2. jcsd
  3. Aug 23, 2013 #2
    That means, this theory will be non-realistic. This is indeed a possible interpretation of the Bell theorem.

    The Bell theorem says that you can not have all of these at once:
    - realism
    - locality
    - casuality
    - Euclidean-like topology of space

    You must sacrifice at least one of these. You've decided to give up on realism. That is one possible explanation.
  4. Aug 23, 2013 #3


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    Staff: Mentor

    You would have to give up a lot more than just a consistent memory. The detector could, for example, record its findings by drilling a hole in a piece of hardened steel whenever it makes a spin-up measurement; we then could bring the two pieces of steel together in a machine that sounds a loud alarm if two holes ever line up.
  5. Aug 23, 2013 #4
    How can it be explained by abondoning Euclidean-like topology of space?
  6. Aug 23, 2013 #5
    If I understand entropy15's intention well, then he thinks of a theory where distant regions remain in some kind of superposition until they meet, when they adjust themselves to satisfy the Bell theorem.
    That means, two distant observers (or two distant steel bars) that record two distant experiments with entangled particles, don't have a fully defined state until they meet. Then, their memories become defined or rewritten.

    Space on the fundamental level could for example be filled with lots of tiny wormholes that connect distant regions. These wormholes could transfer information between entangled particles.
    Similar theory states that entangled particles are connected by some kind of string in higher dimension, which means that actually they are not that far away and communication between them is not superluminal.
  7. Aug 24, 2013 #6
    Thats what I had in my mind. But is it not possible that even before they meet, they have a fully defined state. After they meet they readjust themselves so as to satisfy Bells theorem.

    After all, our past is stored in our present memories. So the present memory can be changed so that we remember things differently.
    Last edited: Aug 24, 2013
  8. Aug 24, 2013 #7
    you refer to a fundamental principle of symmetry (present at the emision of photons pairs), each photon "knows" it orientation (spin mode).

    going to that, slowly but going (studying pair by pair)


    "For instance, to study a pair of entangled photons (created by shooting light into a special crystal where one photon is converted into a pair of secondary, related photons) detection efficiency is all important; and folded into that detection efficiency is a requirement that the arrival of each of the daughter photons be matched to the arrival of the other daughter photon. In addition to this temporal alignment, the spatial alignment of detectors, (each oriented at a specific angle respect to the beamline) must be exquisite. To correct for any type of less-than-perfect alignment, it is necessary to know how many different light modes are arriving at the detector"
    "and those that emit pairs of entangled photons---where the quantum relation between the two photons is exactly right"


    Last edited: Aug 24, 2013
  9. Aug 28, 2013 #8
    Well, anything is possible. I know as much as you. No QM interpretation has been proven, nor even any of it make any experimental predictions.

    You ask if the state before meeting is undefined, or is it defined but rewritten. Well, what is the difference? If both these views yield the same experimental results, then they are the same. Besides, we don't have any way to prove the existence of alternative histories, since they are already gone when we seek for them.

    Let me state it once again: we don't have any explanation for Bell's theorem or any interpretation for QM that is any better than others. For now, we could speculate of anything.
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