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Differentiating realities

  1. Nov 16, 2013 #1
    Sorry, I did not know where to post this as it is sort of a "philosophy of physics" question that I am not sure has an answer and was curious if anyone had any thoughts not grounded in pseudoscience. How can a set of particles interacting in quantum fashion (perhaps a bose einstein condensate, etc) distinguish which universe they are in objectively? ie from the point of view of the objects in quantum superposition until they take a measurement of "the outside world" could it appear to them that different (and contradictory) laws of physics are at play? What I am picturing in my mind is a set of particles that is interacting as a set of overlapping waves so if the overall wave function approximated a sinusoidal wave and the interacting surfaces of various respective sets of objects interacted in a similar fashion could the case be that the "reality" these sets share overlap, but not continuously? ie Think of it as a quantum mechanical analogue to a mirage where the angle for information to be accessed between the realities changes as a function of time similar to how the reflection of the sky in the sand changes as the distance between the observer and the heated surface changes the angle at which light is reflected to the eye via the surface. Does this make sense?
  2. jcsd
  3. Nov 16, 2013 #2


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    Staff: Mentor

    To the best of our knowledge, there is only one universe. Therefore, there are no other realities for the particles to exist within.
  4. Nov 16, 2013 #3
    I thought the many worlds theory with possible variations in the values of the fundamental constants was a standard interpretation of the schrodinger equation?
  5. Nov 16, 2013 #4


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    Interpretations are not theories, and cannot be distinguished from one another by any experimental means at this time. Furthermore, I don't believe there is any way to answer your question about how the particles distinguish which universe they are in. I'm not sure such a thing even occurs in the many worlds interpretation, as I thought that it was the act of measurement that split universes, so at any one time the particles in question only occupy a single universe.
  6. Nov 16, 2013 #5

    it sounds like MWI.
  7. Nov 17, 2013 #6


    Staff: Mentor

    Its easy to get confused reading populist literature.

    A few points:

    1. Its not the Schrodinger equation that needs interpreting - its the so called collapse issue:

    2. What you are thinking of is the Many World interpretation that solves the issue in a very elegant and beautiful way. No collapse actually occurs - everything simply evolves according to the Schrodinger equation.

    3. However due to a phenomena called decoherence, when certain conditions are met, and they generally occur when an observation happens, the wave function can be 'partitioned' in such a way that each partition experiences a different outcome of the observation.

    4. The wavefunction continues on unaffected but the MW Interpretation interprets each partition as a separate world.

    5. This is exactly the same as the standard QM formalism everyone accepts except it is assumed one world is selected and the wavefunction discontinuously changes. That's the collapse issue and different interpretations address it in different ways. In Many Worlds it never actually occurs, which side steps it very neatly indeed.

    6. As I am wont to say all interpretations suck in their own unique and inimitable way. For me this exponentially increasing monstrously large number of worlds is a little too weird - but each to their own - the mathematics is VERY beautiful and that exerts a strong attraction to those of a certain bent. I know because I am one of them.

    Check out:

    It's purely an interpretational thing to get around the collapse issue. There is no way for these worlds to interact with each other or anything like that.

    If anyone could figure out a way it differed from the standard QM formalism everyone accepts it wouldn't be an interpretation - it would be a different theory. But it was deliberately cooked up to not differ so that is highly unlikely - I wont say impossible because I use that word rather sparingly - but pretty close to it.

    If you would like to really understand this stuff beyond the, to be blunt, often confusing sensationalist rubbish in much of the populist 'press' etc (by this I mean the gibberish found in movies like What The Bleep Do We Know Anyway - not the actual thoughtful writings of serious scientists such as Brian Cox) get a hold of the books by Lenny Susskind:

    And the long awaited but soon to be published one on QM:

    Also you can have a look at the video lectures here:

    Last edited by a moderator: May 6, 2017
  8. Nov 17, 2013 #7


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