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Quantum Entanglement at the Big Bang

  1. Sep 9, 2012 #1
    Because the universe started as a point of almost infinite density, wouldn't that mean that every particle in the universe interacted with one another while in that state, crammed together, thereby causing all the particles in the universe to be entangled, including those particles that created human life. If so, what could it mean that our minds, which are entangled with everything we observe in the universe, cause the wave function to collapse. It would seem that our minds are part of the same wave function, so how can the wave function cause itself to collapse?
     
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  3. Sep 10, 2012 #2

    DrChinese

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    Welcome to PhysicsForums, Louie-Pismo!

    Your question is not formulated in a manner suitable to a direct answer. Science centers around testable observations. In that sense, the answer to your question would generally be no.

    First, every particle in the universe did not interact with every other particle. As far as we know, the vast majority of the observable universe has never been in direct/causal contact with this region of space we currently occupy. That may seem impossible, but due to the rapid early inflation this is the standard conclusion. It is always possible that there was an earlier point in time when your condition was met, however, that is pure speculation.

    Second, interacting with a particle does not in and of itself cause entanglement. I interact with my keyboard as I write this, yet we are not entangled. At least, not too much. :smile:
     
  4. Sep 11, 2012 #3

    kith

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    What you probably don't realize is that a subsystem of a larger system is usually not describable by a wavefunction. You have to use the so-called density matrix, which reduces to a statistical mixture of wave functions in the case of maximal entanglement with the environment.

    This opens the door for many interpretations to get rid of the collapse. The many worlds interpretation interprets this statistical mixture as different worlds, which don't interact. Bohmian mechanics says that the actual state is determined by hidden variables. The statistical interpretation says, that QM is only a theory about these statistical mixtures. And so on.

    The standard Copenhagen interpretation however is quite close to DrChinese's comment. It says that it is meaningless to try to describe the measurement process completely quantum mechanically, because in order to get knowledge, we have to separate at least ourselfs from the system we are trying to measure.
     
    Last edited: Sep 11, 2012
  5. Sep 11, 2012 #4

    phinds

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    A couple of notes on your terminology

    First, the universe is not generally believed to have started as a point, for a number of reasons, observed isotropy being one fundamental reason.

    Second "almost infinite" is a nonsense phrase. "Infinite" is a binary characteristic --- something either is or is not infinite. No matter how large a number you posit, the distance from that number to infinity is infinity. I realize you may well already understand this and were just using sloppy terminology, but I point it out in case you do NOT already understand it.
     
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