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Using wave\particle duality to predict future event?

  1. Jun 3, 2010 #1
    This is going to be a little weird so please bear with me for a moment.

    Based on the results of experiments like the delayed choice quantum eraser it would seem that you could use one of these experiments to determine the results of a future random event. Say for example you ran a series of two slit experiments with a detector on one of the slits to determine which path is followed. The information from the detector is recorded to a hard drive. Meanwhile the photons or electrons or whatever create the appropriate pattern on the screen at the end of the experiment. After running say a half dozen of these experiments, a program on the computer would randomly delete (or zero-write the bits, just so there is no chance at all that the information can be recovered) half of the data sets so that the which-path information was unrecoverable. So theoretically speaking, the presence or lack of interference patterns should correctly predict which data sets will be randomly erased and which will not, prior to the data actually being deleted.

    I suppose it is also possible that just the mere recording of the data to a hard drive will prevent any interference patterns but it would seem that as long as you devised a way to randomly “lose” that information after the fact, you could still use the presence or lack of an interference pattern to determine the results of the future random data erasing event.

    If this is true, then you could in turn develop an experiment to predict other random events, such as a lottery drawing. If you could setup the experiment such that there was one data set for each possible outcome, and all data sets that did not correspond with the one that is randomly drawn (the winning lottery combination) get deleted, while only that data set is preserved, then the presence or absence of the interference pattern should correctly predict the random lottery drawing.

    The difficulty would be in designing the experiment but as long as the data can be recorded (or even held) and then “lost” it seems like it should be possible. Because you can see the presence or lack of the interference pattern prior to the data actually being lost it should provide predictive value as to whether or not the data actually will get lost. So as long as you can tie whether or not the data gets lost to the random event, the interference pattern should predict the results of the event, despite it being random.
  2. jcsd
  3. Jun 3, 2010 #2


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    If you record it, you're measuring it, which means that you do not get an interference pattern.

    It doesn't matter one bit for future events whether or not you were measuring in the past, and it certainly doesn't matter whether or not you kept that information.
  4. Jun 3, 2010 #3
    Your detector neither has to record or save the information. The very fact that the recorder detected, without recording, which way the photon went is enough to kill the interference pattern.
  5. Jun 4, 2010 #4
    The delayed choice quantum erasure experiment would seem to contradict that. Although it is for a very short period of time, which-path information is contained in the experiment before being "lost" or erased. When it is erased the interference pattern is formed even if the information is "lost" after the pattern has already been formed.


    This is probably true to some extent though.

    Since the delayed choice quantum eraser uses light and light could theoretically be "held" by placing mirrors in such a way that the photon loops infinitely, you could in effect "hold" the which-path information indefinitely. If you created photon holding containers (mirrors that sent the photons in an endless loop) that could release the photons into either 1) a common path (in which case the which-path information would be lost or erased), or 2) into an individual path (which would reveal the which-path information), then you could in effect create a delayed choice experiment where the choice is delayed indefinitely, as long as you made no effort to reveal which holding container had the photons. Meanwhile the interference pattern (or lack thereof) would already be available for inspection.

    (If you read the experiment you will see why, but from the wiki page there is this: "So far, the experiment is like a conventional two-slit experiment. However, after the slits a beta barium borate crystal (labeled as BBO) causes spontaneous parametric down conversion (SPDC), converting the photon (from either slit) into two identical entangled photons with 1/2 the frequency of the original photon." One of the entangled photons is sent to a screen where either the additive pattern or interference pattern is formed, the other photon goes into further reflection apparatus which is where the 'delayed choice quantum eraser' part exists and where the "holding" containers would be for the theoretical experiment I am describing.)

    So now all you have to do is create the random factor which either releases the stored photons into the common path and erases the which-path information, or releases the photons on their individual paths revealing the which-path information. So the question is, will the presence or absence of the interference pattern correctly predict this? The delayed choice quantum eraser experiment suggests that it will based on the fact that it already does something exactly analogous, albeit in a very short time span. It should not matter if the light takes a nanosecond or an hour to arrive at a place where it's path information is obscured, just as long as it does so before anyone (or anything) makes note of it.
    Last edited: Jun 4, 2010
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