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Many Worlds experimental evidence

  1. Jun 3, 2008 #1
    I keep hearing that the "many worlds interpretation" is experimentally different than the collapse theories. But I haven't heard of anything other than "quantum suicide". Is there anything else?

    As far as quantum suicide, I fail to see how this differs from collapse theories. Isn't each quantum event independent, such that each event has a probability of turning out one way or another? And this goes for collapse theories as well as Many Worlds. So if someone keeps trying to commit 'suicide' with a quantum event, but keeps ending up alive, couldn't this be explained under collapse theories as just being extremely lucky?

    Also, am I mistaken in thinking that actual suicide isn't necessary for the experiment? In other words couldn't a quantum event just be set up, linked to some kind of alarm? If the alarm never goes off, or always goes on, then "many worlds" is true (according to its proponents)?

  2. jcsd
  3. Jun 3, 2008 #2
    Quantum suicide is idiotic. Even its proponents admit that we would see anybody who committed quantum suicide die. There is, therefore, by definition, no way of using this to scientifically verify many worlds.

    And no, it could not be done without actual suicide. The idea is that the consciousness would remain in the universe in which you didn't die - an unfounded assumption to begin with!
  4. Jun 3, 2008 #3
    I don't see why it can't be done without suicide though. All the "does the consciousness persist" question answer is whether in one "alternate universe" it is confirmed that the quantum event keeps returning the same result each time, going against the odds. Why couldn't this just be done with a quantum event linked to an alarm, which scientists could observe? If the alarm never goes off, the scientists could say "ah, this is like if a person kept not being killed in Quantum Suicide!"
  5. Jun 3, 2008 #4
    Because the alarm will always go off exactly as QM predicts it will. How would you force the outcome to be different, or, in the MWI veiw, force yourself into the desired world? You can't. The quantum suicide hypothesis is that - perhaps - your consciousness would only remain in worlds in which you don't die. Which is, like I said, unfounded.

    And if that were true, we'll all find out eventually. Because then some quantum events will conspire in our respective universes to make sure we live forever.

    What nonsense.
  6. Jun 3, 2008 #5


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    It seems idiotic to me too.
  7. Jun 3, 2008 #6
    Well, it is experimentally different because you always have a unitary time evolution in MWI. In the Copenhagen interpretation, the wavefunction really collapses after a measurement is made (and not just in an effective way as a result of decoherence), so you have a non-unitary time evolution.

    I agree that the quantum suicide experiment will not work even if the MWI is true. But another experiment proposed by David Deutsch will work, at least in principle. This involves a quantum computer that is able to simulate someone's brain. Such a computer is used to simulate a person in some virtual reality environment.

    One then sets up an experiment involving the quantum computer that will demostrate to us that the simulated person can exist in a superposition of states. This then proves that the virtual person does not really collapse his wavefunction in the virtual reality, he merely enters into a complicated entangled superposition with his environment.
  8. Jun 3, 2008 #7
    How can a "simulated reality" prove anything about R_E_A_L_I_T_Y?
    David Deutsch has too many assumptions, with no evidence.

    another thing: would the brain simulated be "conscious" ? if so, wouldn't that be torture, creating a conscious being in a solipsitic existance only for a experiment?
    must be a mice brain otherwise complete torture.
    Last edited: Jun 3, 2008
  9. Jun 3, 2008 #8
    To the best of my knowledge, there is no experimental evidence, nor is their likely to be.

    If causality were violated (eg, general relativity seems to allow for wormholes through time as well as space) in an experiment, there would seem to be some evidence to support it (since it would be useful for resolving temporal paradoxes). Unfortunately, such an experiment seems more than a little far-fetched and amounts to little more than speculation.

    Many worlds always seemed like a better explaination than the Copenhagen interpretation, but, if you asked which interpretation is more scientific, I would have to conclude the Copenhagen, Occam's razor being what it is.

    I have not taken a quantum physics class yet, so you may want to fact-check my response with someone better-versed in quantum mechanics.
  10. Jun 3, 2008 #9


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    Sounds like you're making an assumption without evidence. :wink:
  11. Jun 3, 2008 #10
    The quantum compuer itself would behave in a non-unitary way if the Copenhagen interpretation is correct. That's a verifiable prediction for the people in the real world. The simulated person's observations are not what matters here (other than that they would cause the wavefunction of the quantum computer to collapse).

    What we do is we let the simulation run in a superpostion of two states and then we do a special measurement that will enable us to tell wheter or not the quantum computer's state has collapsed.

    If we assume that the simulated person has real consciousness, then the Copenhagen principle would predict that the simulated person's observation would collapse his virtual environment. But then the quantum computer would have undergone a non unitary evolution, which is detectable.
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