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Schroedinger's test-tube babies

  1. Dec 24, 2005 #1
    I have devised a thought experiment to test the Copenhagen interpretation.

    Let's say we have an elementary particle which has a 50% probability of emitting an alpha particle in an hour. We have a measuring device which is allowed one hour to measure whether or not an alpha particle is emitted. If an alpha particle is detected, then a signal is sent to an apparatus which causes a sperm to meet an egg cell in a test-tube. Let's say that the lab is constructed in such a way (use your imagination.....it's the <whisper-voice>future</whisper-voice>) that the subsequent baby created will grow, have proper nutrients and what-not, so that we can check back in 15 years to see if there is a teenager there (the child will not be allowed to interact with any person or leave evidence of its existence outside the lab). But we leave language-learning material in this lab such that the child, if sufficiently clever, can learn to speak on its own. Now we check back in 15 years, and if there is indeed a teenager, we ask him, "how long have you been alive?" If he says, "15 years", then the alpha particle was emitted irrespective of any observation.
  2. jcsd
  3. Dec 24, 2005 #2
    Considering that the child would do a hell of lot of interacting with it's environment this is not a very good thought experiment.
  4. Dec 24, 2005 #3


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    Please don't take this the wrong way, but after reading a number of your posts, you are doing things in reverse. You need to understand the mathematical formalism of the principle first before trying to illustrate or test something using a thought experiment or analogy. Without doing that, you are basing your thought experiment on nothing more than superficial understanding. This will lead to many problems.

    I will also suggest you re-read our Guidelines that you have agreed to, especially regarding speculative posting. While we certainly encourage questions on specific issues that one doesn't understand, we strongly encourage that postings like this be based on a clear understanding of the subject matter. And in physics, that means a mathematical formalism of the principle. Without that, all you have is a hand-waving understanding, and that is just way to ambiguous to address.

  5. Dec 24, 2005 #4


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    I doubt it is possible to actually isolate a lab that thorougly. Since the moderators here don't seem too happy with your post, you might try having it movedit to the philosophy forum, to see if it is better received there - it appears to me you are mainly interested in the philosophy of QM.

    Currently, I try to take the position that any of the philosphical interpretations of QM can work, though I have a bit of a problem taking the Copenhagen interpreation too seriously. It's just too hard to pin down what the "collapse of the wavefunction" actually _means_.

    In your specific example, you might ask why teenager isn't able to "collapse the wave function", while _you_ are. What _really_ causes collapse? (Don't ask me, ask someone who takes the Copenhagen interpretation more seriously than I do).

    This may sound like I'm a rabid many-worlder, but actually I find just about all of the interpreations of QM hard to swallow. About the best thing I can say for the theory of QM is that it actually _works_, and it works very, very, very well.

    Which is about all you can ask of a theory, really.
  6. Dec 25, 2005 #5
    Your thought experiment is fine in the sense that checking on the teenager in 15 years is essentially similar to waiting a very long time to open the box and check on Schrodinger's cat. The question of when the mixed-up physical possibilities of "teenager" and "no teenager" became seperate physical possibilities and when one actually happened is a bit like the standard "alive cat" and "dead cat" scenarios. When did they seperate? When did one occur? Does any living thing observe itself? In this case, was the teenager there before we checked? These are tricky questions from the older way of looking at it.

    The modern way of looking at it involves something called "decoherence" in which the interaction with the environment means that mixed-up physical possibilities seperate in billionths of a second without any concerns about observers and observation like there used to be.

    You might find a lot of books, articles and many textbooks are not up to date or mislead you or emphasize the wrong details. Beware! This is a very tricky area of thought and you'd be amazed at some of the famous and otherwise brilliant scientists who've fallen into traps. :smile:
    Last edited: Dec 25, 2005
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