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Are we still entangled?

  1. Aug 5, 2012 #1
    If everything came from the same singularity prior to the Big Bang, are we still entangled? If yes could we retrieve information of the whole Universe from one single particle? If not when and how were we de-entangled?
     
  2. jcsd
  3. Aug 5, 2012 #2
    Entanglement is broken once you perform a measurement/observation/interaction. For everything to be still entangled, you'll have to stick to a solipsistic(mind-dependent) variant of the CI.
     
    Last edited: Aug 5, 2012
  4. Aug 5, 2012 #3

    ZapperZ

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    You need to look closer at these Bell-type experiments. Why did they all had to go through such gymnastics and under such conditions to detect these entanglement? Why are entanglement experiments using particles (instead of photos) can only be done for such a short distance?

    Preservation of entanglement is NOT easy!

    In fact, this experiment has shown that just on interaction with another system can eliminate the information from the original system. Just ONE!

    It is why these experiments are not easy to perform in the first place.

    Zz.
     
  5. Aug 5, 2012 #4
    Thanks Maui and ZZ.
    Maui, if the human mind is to participate, at which level (reception, analysis or response)? ZZ, isn't there only one system from one singularity?
     
  6. Aug 5, 2012 #5

    ZapperZ

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    I have no idea what this is.

    If there is only ONE system, then what is interacting in that reference that I gave you? Why did we lose coherence for the single-particle system?

    Zz.
     
  7. Aug 5, 2012 #6
    we always remain entangled...its just that the (entanglement) partners change....

    AlSo, also I think the information is never lost but practically impossible to retrieve, (except in case where is enters a black hole or encounters similar quantum phenomena)
     
    Last edited: Aug 5, 2012
  8. Aug 5, 2012 #7
    If everything is constantly in superposition, then there is a form of entanglement to every 'particle' and it leads back to my post 2.



    This is a philosophical issue and this approach in particular raises a few eyebrows in these quarters. I'd repeat what i stated earlier - the belief that everything is entangled leads to the inescapable conclusion that naive realism is false, and since all known science is based on naive realism, it's just a small logical step towards the counter-intuive conclusion. See here:

    "The realist view is that objects are composed of matter, occupy space and have properties, such as size, shape, texture, smell, taste and colour, that are usually perceived correctly. We perceive them as they really are. Objects obey the laws of physics and retain all their properties whether or not there is anyone to observe them.[1]"

    http://en.wikipedia.org/wiki/Naïve_realism
     
  9. Aug 5, 2012 #8
    I figured out what you want to know. But you are asking the wrong question. You want to know if everything is still entangled as everything had emerged from the same system, can not anything be determined using this entanglement.

    Well, the answer is maybe everything is still entangled. But we have no way of looking at it. You see when we talk about electron's probability cloud, we can still imagine that a deterministic path of electron could still exist. But its the Heisenberg's uncertainty principle that prevents us from having that determinism.
     
  10. Aug 9, 2012 #9

    I dunno if anyone cares, but it seems to me that realism is statistical. Big objects with lots of particles behave so closely to realism that it is virtually true. Elementary particles, not. I find it better to think of them as field excitations. That makes everything much easier.
     
  11. Aug 9, 2012 #10

    bhobba

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    Come again. First I have heard of that. Decoherence for example leads to the conclusion the state of the system after measurement depends on what you are measuring - as does bog standard QM and the Kochen Specker theroem - but it gives a mechanism for it. The quantum system gets entangled with the observational apparatus so the final state depends on that apparatus in complete opposition to naive realism.

    In relation to the original question the quantum state of the whole universe presumably evolves according to some unitary operator so everything remains in superposition and hence entangled. But since QM is a theory about observational outcomes there are issues in principle in modelling the entire universe as a quantum state since there is nothing outside it to give it meaning. String theory however may provide an out in that some models predict a lot of different universes. But aside from that for the objects in the universe they generally get so entangled with other objects in an irreversible way any original information is long since lost.

    Thanks
    Bill
     
    Last edited: Aug 9, 2012
  12. Aug 9, 2012 #11

    bhobba

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    Indeed realism does not imply the stuff out there can be predicted with certainty - it merely means it is external to us and exists independent of us. With decoherence quantum systems are like that - they have a definite state but we can only determine the probabilities of what the state is.

    Thanks
    Bill
     
  13. Aug 9, 2012 #12

    You might have misunderstood the context in which i used "it's just a small logical step towards the counter-intuive conclusion"... which should have ended in "that naive realism is wrong" but i thought it was obvious from my previous posts in this thread. This has implications for the newtonian worldview utilized by virtually all fields of science - from medicine and biology to geography and history.
     
  14. Aug 9, 2012 #13

    bhobba

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    Fair enough.

    Thanks
    Bill
     
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