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Bose einstein condensates and GR?

  1. Aug 8, 2013 #1
    If time is constantly moving the direction of increasing entropy and quantum systems are time symetric then how do macropscopic entanlged systems such as bose-einstein condensates relate temporally to themselves and larger systems of which they might be subsets? Because BECs are large enough to be be affected by GR and yet obey the laws of quantum mechanics what kinds of observations/experiments could be utilized to take advantage of their features in order to better understand the relationship between GR and QFT?
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  3. Aug 9, 2013 #2


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    What do you mean with "relate temporally to themselve and larger systems [...]"?

    Every particle is affected by gravity, and every particle obeys the laws of quantum mechanics.

    It is not an issue to combine weak gravitational fields with quantum mechanics. Experimentally, this can be done with neutrons (1) and molecules (I think http://www.nature.com/nnano/journal/v7/n5/full/nnano.2012.34.html?WT.ec_id=NNANO-201205 is the right reference).
    Last edited by a moderator: May 6, 2017
  4. Aug 9, 2013 #3
    Sorry, this was a eureka moment I had while listening to Leonard Susskind's Black Hole Wars. I will have to re-download the audiobook so I can find the exact quote so I can say exactly how it influenced my thoughts on the question exactly. Basically, he made a comment about quantum systems being time symmetric and not being able to draw an arrow of time due to entropy for those systems, so how would a large bose-einstein condensate interact in terms of time with other massive astronomical systems? The bosons would curve spacetime in some way which would make them have an impact on other astronomic phenomena and vice versa so what would the spacetime of the bec look like and how would that differ from say a bunch of entangled photons interacting on the subatomic level? Also, would it be possible to sustain the the condensate and scale it up? For example say you had a collection of bosons with 3 solar masses encased in a sort of sheath in vacuum what would the condensate look like as it collapsed so a singularity? I am trying to come up with "thought experiments" that could be avenues for GR and QFT unification

    I have only taken up to electromagnetism though, so I am still new to upper level physics esp the mathematics
  5. Aug 13, 2013 #4
    I don't know what source material you are referring to here, but I think there is no problem in using entropy to define an arrow of time for "quantum systems." *All* systems are quantum mechanical, so the second law would be in serious trouble if entropy did not increase with time in quantum mechanics.
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