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Did Entanglement Spook Einstein?

  1. Jan 23, 2005 #1
    For more than 70 years, QM advocates have misrepresented Einstein's EPR work. Once it becomes clear what Einstein was really saying, it should be very difficult to stick with Bohr's bizarre interpretation of entanglement.

    Among the FEATURE ARTICLES (Cover Story) of the Scientific American,
    January 2005 issue is:
    "Best-Kept Secrets - Quantum cryptography has marched from theory to
    laboratory to real products" This article is found at:

    http://www.sciam.com/issue.cfm

    The following is a quote from that article:

    "Ultimately cryptographers want some form of quantum repeater--in essence, an elementary form of quantum computer that would overcome distance limitations. A repeater would work through what Albert Einstein famously called "spukhafte Fernwirkungen," spooky action at a distance. Anton Zeilinger and his colleagues at the Institute of Experimental Physics in Vienna, Austria, took an early step toward a repeater when they reported in the August 19, 2004, issue of Nature that their group had strung an optical-fiber cable in a sewer tunnel under the Danube River and stationed an "entangled" photon at each end. The measurement of the state of polarization in one photon (horizontal, vertical, and so on) establishes immediately an
    identical polarization that can be measured in the other.

    Entanglement spooked Einstein, but Zeilinger and his team took
    advantage of a link between two entangled photons to "teleport" the
    information carried by a third photon a distance of 600 meters across
    the Danube. Such a system might be extended in multiple relays, so
    that the qubits in a key could be transmitted across continents or
    oceans. To make this a reality will require development of esoteric
    components, such as a quantum memory capable of actually storing
    qubits without corrupting them before they are sent along to a
    subsequent link. "This is still very much in its infancy. It's still
    in the hands of physics laboratories," notes Nicolas Gisin, a
    professor at the University of Geneva, who helped to found id
    Quantique and who has also done experiments on long-distance
    entanglement."

    The SciAm article claims that "Entanglement spooked Einstein." This is definitely not true. Entanglement is just normal classical physics. There is absolutely nothing mystical about entanglement. Why would Einstein be "spooked" by normal classical physics? What spooked Einstein was Bohr's interpretation of entanglement that claimed that the particles were in a state of superposition until observed. This is what "spooked" Einstein since superposition requires faster than light "spooky action at a distance" in order for the polarization correlation to be preserved. It was Einstein's Special Theory of Relativity that established that no physical entity (or signal) could travel faster than light. According to Christopher Fuchs (Sept 04 SciAm), if "spooky action at a distance" was possible, then engineers should be able to send signals using "spooky action at a distance." But they can't. It should be crystal clear that Bohr's superposition argument cannot explain the EPR crypto-system correlations.

    Here is what does explain the EPR crypto-system correlations. The Einstein point of view is that when the two photons are created, they both have a definite polarization that is negatively correlated with the other due to conservation of spin (this is the cause of the entanglement), but we do not know what they are. When one is measured, we then know the polarization of the other (it is the opposite polarization). Since both photons have a
    definite polarization from birth, there is no question of whether the measurement of one photon affects the polarization of the other. This is the core of Einstein's "element of reality" argument:
    "If, without in any way disturbing the system, we can predict with certainty (i.e. with probability equal to unity) the value of a physical quantity, then there exists an element of physical reality corresponding to this physical quantity."

    Superposition has NEVER been observed. "Spooky action at a distance" has NEVER been observed. Bell's inequality cannot "prove" something that does not and cannot happen. Mathematics cannot prove the existence of anything that has NEVER been observed.

    "I've said it before, I'll say it again:
    Can a dog collapse a state vector?
    Dogs don't use state vectors.
    I myself didn't collapse a state
    vector until I was 20 years old."
    - Christopher A. Fuchs

    All the best
    John B.
     
    Last edited: Jan 23, 2005
  2. jcsd
  3. Jan 26, 2005 #2
    I'm suprised anyone has time to argue about the correct interpretation of QM. None have been proved or disproved and all the popular ones result in almost identical predictions. Furthermore, there isn't an interpretation out there that agrees with experiment and doesn't have some compelling elements plus a little madness.
     
  4. Jan 26, 2005 #3

    JesseM

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    Are you arguing that Bell's inequality has not been observed to be violated experimentally? Or are you arguing that it is possible to violate Bell's inequality and still believe in hidden variables (ie the belief that each photon has a definite polarization from birth) without the need for spooky action at a distance? If the latter, then you haven't understood Bell's argument, it clearly shows that violations of Bell's inequality are incompatible with local hidden variables.
     
    Last edited: Jan 26, 2005
  5. Jan 26, 2005 #4

    vanesch

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    But this is exactly the reason why we argue about it :tongue2:
    You cannot distinguish them except on vague criteria, just as political opinions. Hence you can talk a lot, and have endless, passionate arguments :rofl:.

    If it were just a matter of purely scientific inquiry, it would be too boring: one would just do the experiment and that's it...

    cheers,
    Patrick.
     
  6. Jan 27, 2005 #5
    If they did a properly-designed set of experiments, and maybe had an independent statistician to help make sure they analysed them fairly, that might indeed be it! Every single Bell test experiment to date would be dismissed as having been utterly unable to discriminate between QM and local realism and, perhaps more importantly, local realism would have proved itself superior in predictive power over all possible parameter spaces, not just the tiny space of measure zero covered by any one individual Bell test experiment!

    Caroline
    http://freespace.virgin.net/ch.thompson1/
     
  7. Jan 27, 2005 #6

    DrChinese

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    That's singing a different tune! Over in the "Fresh look at EPR" thread you said this when I asked for specific predictions of LR to compare to experiment:

    "The figures are meaningless. The idea that LR predicts just one figure is wrong: LR represents the genuine scientific approach to modelling the real world, and it is absolutely right and proper that it should give a different result for each experiment."

    I surmised there that you are unable to provide specific LR predictions for Bell tests. P.S. If you can, please provide the LR prediction for correlations in the Rowe experiment you cited at 0 and 22.5 degrees.
     
  8. Feb 1, 2005 #7
    Long silence noted...
     
  9. Feb 1, 2005 #8

    ZapperZ

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    Then explain (i) the recent SQUID experiment out of Stony Brook (ii) the presence of the energy gap between bonding and antibonding bands in H2 molecule, etc. etc... There are TONS of observations, especially from chemistry and material science that can ONLY be explaned via superposition. No one and no other theory has even offered an alternative explanation for such observations.

    Zz.
     
  10. Feb 1, 2005 #9
    No i think you are wrong here, it is the action at a distance (thus the entanglement) that spooked Einstein. When one electron-polarization is measured, the other polarization instantly becomes " a fixed value" (ie : the wavefunction has collapsed or the "superposition has been broken") nomatter what the distance between the two constituent particles of an entangeled pair is. This implies faster then light phenomena...

    In order to be abla to compare their results both observers need to make one phonecall (this is a "classical" thing), so there is no faster then light communication.



    In QM photons have a definite polarization AFTER the measurement. The formalism clearly states that physical data can only be acquired after performing such measurements. The wavefunction (prior to a measurement) only contains all physical data of some QM-system or state.

    You need to look at the formalism the right way.

    What ?? Then how about stuff like the entire hydrogen energy spectrum for example. Are you denying these results ??? This can't be the case because they are all backed up with experimental "consent"...

    Or, how about the entire atom and molecule-physics , or laser-physics or for that matter photonics ???


    regards
    marlon
     
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