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Reason for wavefunc collapse? Being observed or Being known by some conscious entity?

  1. Jan 23, 2012 #1
    Or Is it ever possible to make the distinction between these two ? (Maybe this distinction cannot be in a physical sense.)

    This question bears in my mind for some time. I favor the second alternative, at least at the philosophical level, but what do you think ?

    And Is there any experiments regarding this question ?
     
  2. jcsd
  3. Jan 23, 2012 #2
    Re: Reason for wavefunc collapse? Being observed or Being known by some conscious ent

    no clear answer.

    "the expression wave function collapse is a fundamental problem in the interpretation of quantum mechanics, and is known as the measurement problem.."

    Some discussion here:
    http://en.wikipedia.org/wiki/Wavefunction_collapse
     
  4. Jan 23, 2012 #3
    Re: Reason for wavefunc collapse? Being observed or Being known by some conscious ent

    See the thought experiment in 'Sneaking a Look at God's Cards' by GianCarlo Ghirardi, in regards to whether a macroscopic apparatus does the collapsing or not.
     
  5. Jan 23, 2012 #4
    You've mentioned this on several threads. Could you elaborate on what this thought experiment is?
     
  6. Jan 23, 2012 #5
    Re: Reason for wavefunc collapse? Being observed or Being known by some conscious ent

    I've wondered about this. Observation, I think, is somewhat misleading. In the double slit experiment a detector is placed at the slit, collapsing the wave and leading to the restoration of a bar pattern. But no direct observation occurs. Interaction, however, does.

    Somewhere abouts in these forums, it is mentioned that the idea is 'measurement' rather than 'observation'. I ask if this cannot be extended further to a question of 'interaction'.

    If the wave function actually exists as a general disturbance of energy, then any interaction might well cause excitation to the point of the appearance of a particle. How this would remove the general disturbance is a key question. This is partially accepted, but I stress that there is apparently no consensus of the real nature of the wave function, with some contending it is only maths. If you want peace of mind you will need to do one of two things: pick a choice and be happy, or study quantum mechanics and solve it for us once and for all.
     
  7. Jan 24, 2012 #6
    Re: Reason for wavefunc collapse? Being observed or Being known by some conscious ent

    I agree with you, I guess it is unknowable whether consciousness causes collapse or not. However, I would like to know if it is falsifyable.

    From wikipedia (http://en.wikipedia.org/wiki/Quantum_mind%E2%80%93body_problem#Criticism [Broken]), "The hypothesis of consciousness causing collapse has been criticized also on the basis of empirical evidence. Yu and Nikolić claim that the existing empirical evidence can be used to falsify the predictions derived from the collapse-by-consciousness hypothesis.[35]"

    From wikipedia reference, http://www.danko-nikolic.com/wp-con...kolic-Qm-and-consciousness-Annalen-Physik.pdf

    "it was shown that if “which-path” information was in principle obtainable, then even though no actual attempt was made to extract this information (i.e., to measure it), no interference pattern was found."

    So are these valid objections for consciousness hypothesis ? What is the meaning of the obtainable information ? As far as i understand from Q. Eraser Delayed Choice experiments, time is not an issue, measurement can be made in a very far future, but that affects the experiment at the moment. So if an information is obtainable, then there is chance that it can be perceived by some consciousness at the future.

    If obtained information is destroyed after some time, i think (but i am not sure) wave-function would not collapse. So what happens behind scenes, Wave function collapses (because of obtained information) then re-constructed because information obtained destroyed ?? This does not make sense to me.
     
    Last edited by a moderator: May 5, 2017
  8. Jan 24, 2012 #7

    Ken G

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    Re: Reason for wavefunc collapse? Being observed or Being known by some conscious ent

    I don't think so. There's a common misconception, in my view, about the difference between "collapse" and "decoherence." The latter is a fairly well understood aspect of quantum mechanics theory, and is also well observed, in experiments like the ones you cited. There's no question that interactions can docohere a projected wave function onto its various eigenstates of that interaction/measurement, regardless of whether or not a consciousness is involved in that measurement. But this only produces a "mixed state" when you project onto the observable subspace-- it still does not produce a definite outcome. Decoherence just doesn't do that. So the question of "collapse" remains unanswered: what chooses the actual outcome that is perceived? Some think there is a dynamical collapse that happens in the measurement that is not described by quantum mechanics (the Copenhagen interpretation says this), some think there is a dynamical collapse in the brain of the perceiver that is not described by quantum mechanics (and the Copenhagen interpretation can easily be modified to say this), while others say the collapse never actually happens at all, it is just an illusion that happens in the mind (the Many-Worlds view holds this). Other interpretations say various other things, and none of these are currently testable. Thus the answer must await a new theory that does not admit to all these various interpretations.

    Personally, I suspect that such a new theory will end up siding with the consciousness does cause collapse, along the lines of Wheeler's view, but I don't think it will be a dynamical process-- I think it will change how we view what physics is doing, and old notions of what "dynamics" is will have to change with it. But who cares what I think, the future will tell.

    Delayed choice experiments bring in a new wrinkle-- the insight you get when you correlate observations. Much ballyhoo is made of the fact that if you look at which slit the particle goes through, you get only a pair of single-slit diffraction patterns, rather than one double-slit pattern. But I think delayed choice experiments make it quite clear what is and is not happening there-- the pair of single-slits pattern can be made in one of two ways:
    1) incoherently superimposing two double-slit patterns that are shifted relative to each other.
    2) incoherently superimposing two single-slit patterns that are shifted relative to each other.
    If we track the which-way information, and correlate, we are led to conclude that #2 is what happened, but if we erase the which-way information, and correlate, we are led to conclude that #1 is what happened. However, since #1 and #2 give the same final result, it is just an illusion that either of those ways "really happened"-- reality was ambivalent to the distinction all along. So delayed choice experiments don't expose something reality is doing, they expose something reality doesn't need to do and so is ambivalent about. The only physical effect is that sideways shift that is induced by the apparatus that is able to detect which-way information-- whether or not that information is erased. Thus what you are worried about is something that reality does not adjudicate-- it is a non-issue.
     
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