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Schroedinger's apple

  1. Jun 17, 2013 #1
    This evening I enjoyed a dessert consisting of an unknown fruit emersed in chocolate pudding. I could not identify the fruit by its appearance, and when I consumed it, it took several seconds before I could identify the piece of fruit as a plum. I began to contemplate whether Schroedinger's effect could theoretically apply here. Is there a possibility that until the moment of recognition the fruit could have been in a state of quantum flux representing many different possible types of fruit until it was recognized. I know that the fruit consisted of numerous molecules and thus the probabilities would be immense for it to have been any other fruit. Assume that I have never had any contact with the chef, nor at any time will have contact with any other person whom would confirm the identity of the fruit.

    One might argue that it was already a plum because the chef chose a plum and thus it was already observed. However, could it have changed after that observation if the chef would never observe it again. Thinking about it in terms of the double slit experiment, what if one observer aims a particle to be shot through one of the slits, but halts observation after this point and cannot confirm that it actually went through the slit at which it was aimed. What if a second observer actually records which slit the particle went through, after the particle has already hit the screen. Assume that there is no communication ever between observer 1 and observer 2. Could there be discrepant observations between the two?
  2. jcsd
  3. Jun 18, 2013 #2


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    Your question presupposes that you are the only one who is observing the plum. You are only one observer; as long as there was any observer (which does not need to be a sapient or even live observer: anything which interacts with the plum to cause a change of energy), and if enough of the plum's particles were observed to make it fit the definition of a plum, then it was a plum. At least, in the ontological spirit of physics. Of course, as far as an epistemological question, you could ask when you know that it is a plum, but that is not what Schrödinger was talking about. Of course, if enough of the particles of the plum were somehow isolated from its surroundings until you got it, then you might put it in with S's infamous cat. But in that case it would be pretty cold and inedible.
    Or, to paraphrase an apocryphal statement by Freud, sometimes a plum is just a plum.
    As far as your variation on the two slit experiment, there is the problem that you have the first "observer" aiming a particle, but not observing where it went. Therefore, it isn't really an "observer", and so there is no observation to compare to the observation of the second observer. Also, the only way to observe which slit it went through would be to put measuring devices on the slits themselves; a screen would not suffice for a single particle.
    Anytime you have two observers observing the same particle, you are going to have to do it in sequence, so that in cases where there is fuzziness, the first one will destroy the initial state, so in effect the second one is not measuring the same particle. So yes, there can be a discrepancy in the two measurements.
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