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Observer types to make the wavefunction collapse.

  1. Apr 7, 2010 #1
    Hi there, I'm not extremely adept at understanding what I like to think of as the "Philosophical" side of QM but I find I have a problem with some aspects of an interpretation of the wave function collapse. I also could be misunderstanding what people are saying.
    When people talk about particles being observed and the wave functions collapsing, It almost seems as if some people think that the observer must be a human. For example, Schrodingers cat: He is said to be half alive and half dead until observed, but doesn't the cat observe whether he is dead or not?
    More fundamentally i would think that solely interactions between fundamental particles would be what we call observers. I just saw in another thread something along the lines of "Well what happens if the observer dies right after taking a measurement?" on whether or not the wave function can 'un-collapse' .Am i just crazy or do some people talk as if humans have to be the ones to collapse the wave function? I don't agree with this.
  2. jcsd
  3. Apr 7, 2010 #2


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  4. Apr 8, 2010 #3
    Yeah that's what I would think definitely.I'm saying that it seems some rhetoric would suggest otherwise.
  5. Apr 8, 2010 #4
    Wave function collapse is a highly debated area, and to my knowledge there is no clear cut answer. My question for a while has been why is only when we "observe it" does it collapse. Everything in the universe is one big system as everything interacts by gravity etc, and so there is never an outside observer. Therefore the electron in an orbital will always be coupled to the observer no matter if an "observation" is made or not.
  6. Apr 8, 2010 #5
    Wave function collapse only makes sense in the context of there being a closed system and an outside observer. When the system ceases to be closed (say, by opening a door or making a measurement) it's wave function collapses. Any system studied in isolation (this includes theoretical models) qualifies as 'closed'.

    (This is not a philosophical matter; it's simply part of the whole idea of there being a wave function.)

    If you read the above paragraph closely, you will find all the answers you need.
  7. Apr 8, 2010 #6
    You can have detecting wire loops around the slits in youngs experiment, and it seems clear that human observation does not necesarily collapse the wave function.

    "weak measurement" suggests that humans can observe and not collapse the wave function.

    No one has the first clue about wave-particle duality, it's neither objective nor subjective.
    Last edited: Apr 8, 2010
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