Layman's questions regarding Measurement Problem

  1. Not sure if anyone will be able to answer these questions but it would be good if someone would give it a shot.

    A friend recently explained the measurement problem to me and i thought of a few questions which he was not able to answer.

    A) Do animals count as observers, and can they cause wave function collapse?

    B) If i were in the same room as the experiment while observing the electrons via an observation device then as i understand it the wave function collapse will occur. But, what would happen if i were one the other side of the planet, viewing the experiment through via data stream?

    C) If i am controlling the experiment but not observing observing it, will the wave function collapse occur?

    D) If a computer program that was sentient observed the experiment, would the collapse occur? I know that nobody actually knows the answer to this but some theories would be great.

    Thank you in advance guys.

    Sorry if these questions are lame but this has really intrigued me and i can't seem to find answers to my questions due to the fact that most papers i find on the subject are written in what may as well be Greek to me.
  2. jcsd
  3. StevieTNZ

    StevieTNZ 1,172
    Gold Member

    There have been no definite experiments done to rule out explanations on how collapse occurs. It MAY be animals collapse the wave function, it MAY be our consciousness does. That's all we can say right now.
  4. It may be animals, but I think it's highly unlikely because that gives special preference to things that, from nature's point of view, don't seem to be special. An electron is an electron, whether or not it is in an animal's brain. So, if it turned out that animals collapsed the wave function, that would be very bizarre, indeed, and there is certainly no reason to believe that that is the case. However, the phenomenon of consciousness is a mysterious one that seems, at least on the face of it, to be a manifestation of nature giving animals a preferred status, so I could be wrong.

    For that matter, wave function collapse seems to me to be a mere procedure for predicting the results of experiments, with no clear relation to reality, as such. What is going on behind the scenes remains a mystery.
  5. I have read that some people argue, not only animals but all the matter around us is consciousness. This is to say that the reality existed even before the life appeared on earth.
  6. StevieTNZ

    StevieTNZ 1,172
    Gold Member

    There is also Bohm Mechanics, which 'apparently' mimics quantum predictions, except reality exists at all times, without the need for a wave function collapse.
  7. StevieTNZ

    StevieTNZ 1,172
    Gold Member

    I might also add decoherence is used by some to explain the measurement problem. Though there are many that argue decoherence does not lead to any solution of the problem.
  8. Yes. Anything big enough collapses the wave function of a system observed by it.

    But also a photodiode, or any other measuring device. These are far more reliable than animals,
    whom to teach to measure something well is really difficult.

    In physics, one usually chooses the simplest explaining set-up - so one doesn't complicate things by replacing a reliable device by something complex such as an animal or a human.

    Computer programs are not observers, as the former are not material things. But if a program is in control of a measuring process the.the controled measuring devices are observers.
  9. StevieTNZ,

    Can you explain how does the reality exist all the time without wave function collapse according to Bhorm mechanics?
  10. Yes, animals collapse the wave function. I was talking about whether conscious creatures are the ONLY things that do so, which some people have argued for.
  11. The point is that it is possible to consider a measurement as just time evolution, provided that there's some other collapse later on. So, one idea is that maybe the cut-off point where the "real" collapse happens is with conscious observers.

    Also, some people don't believe in collapse at all.
  12. 800
    Science Advisor
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    rpt - I'm not sure if I'd consider something published in the Journal of Cosmology reputable. At all.

    I'm uncomfortable with the idea that it requires a "consciousness" to collapse a wave-function. To me, that sounds more like pseudo-science than MWI. Photodiodes collapse wave functions, and unless your definition of consciousness is pretty broad, it's not going to include that.

    The measurement problem is interesting, and I don't think it's solved by invoking consciousness.
  13. DaveC426913

    DaveC426913 16,541
    Gold Member

    Observation is not a matter of living things at all. In a quantum sense, think of observation more like 'interaction'. Atoms can interact with other atoms. Very simplistically, this is effectively an observation.
  14. I don't like the idea, myself, but see, for example Sudbury's book Quantum Mechanics and the Particles of Nature, Chapter 5. He mentions this idea there. You don't have to include photodiodes because, as I said, you can actually incorporate any measurement into Schrodinger evolution, as Sudbery explains in his book. But the catch is that it just pushes the problem somewhere else, rather than solving the problem. So, the idea was to push the problem into consciousness. Probably, whoever put forth this idea would admit that it was speculative, at best.

    I don't THINK collapse has anything to do with consciousness, and there is no reason to believe it does, but it's a vague possibility.
  15. 800
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    Wait, what? The entire point of the measurement problem is that it cannot be encoded into Schrodinger evolution! Do you have a paper on this subject?
  16. Yes, and that's why I said, it doesn't solve the problem, just pushes it somewhere else. There is a collapse, eventually, but it may happen in a later experiment.

    The place where I read about this is Sudbery. That's the only reference I know. He's not claiming that you can incorporate measurement into Schrodinger evolution, exactly. Read it and you'll see.
  17. 800
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    Then what is he claiming? I'm just going on what you claimed he said.

    I don't much fancy tracking down a book just to see a proof. And anything can be written in a book. There must be a paper on the topic, surely. Does this interpretation have a name?
  18. DaveC426913

    DaveC426913 16,541
    Gold Member

    If one goes back to Schrodinger's poor cat in the box, one can easily imagine putting the entire contraption in a sealed box with a camera that records whether the cat is alive or dead upon opening the inner box. But this just means there are two states inside the outer box - one where the box was opened and the camera imaged a live cat, and the other where the box was opened and the camera imaged a dead cat. You've collapsed a function but you've just pushed the problem outward one box.

    You could observe the experiment, check the camera recording, which would collapse it into one state or the other - but what if someone put you and the contraption in a box and did not observe you? There'd be one state where you saw a camera that detected a dead cat, and another state where you didn't. It wouldn't collapse until you were let out of the box and observed.
  19. Well, maybe I will go check it out for you, and post when I have it figured out. It's been a while since I have thought about it.

    Roughly, you consider the measuring device as some huge quantum mechanical system.

    I'll have to post about it later when I have time to work it out/look it up. There must be some old papers that discuss these things. The fact that it is in a book doesn't really matter. He proves what he proves.

    I don't know if it has a name.
  20. 800
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    Right. Thanks. I've seen that before, it's rather obvious in formal notation. It certainly doesn't solve anything though, unless you're fond of MWI. (Which I kind of am. I blame my advanced theoretical physics lecturer for that)

    homeomorphic - it's fine, DaveC has explained his argument, I've seen it before.
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