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Wave function collapse causes gravity? (article title)

  1. Feb 12, 2009 #1

    MTd2

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    Gold Member

    http://arxiv.org/abs/0902.1464

    Does wave function collapse cause gravity?
    Authors: Lajos Diósi
    (Submitted on 9 Feb 2009)

    Abstract: We give a twist to the assumption - discussed in various earlier works - that gravity plays a role in the collapse of the wave function. This time we discuss the contrary assumption that the collapse of the wave function plays a role in the emergence of the gravitational field. We start from the mathematical framework of a particular Newtonian gravitational collapse theory proposed by the author longtime ago, and we reconciliate it with the classical equivalence principle.
     
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  3. Feb 12, 2009 #2
    If GR proceeds from a Quantum Gravity theory, then classical GR is also the result of quantum effects. That means that the measurement of a gravitational field is also a collapse of a type of wavefunction in QG. The question becomes how much of particle wavefunctions are involved in the collapse of QG wavefunctions. Or, how much are particles coupled to or entangled with quantum gravitity?
     
  4. Feb 15, 2009 #3

    Fra

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    Some personal reflections.

    This "basic idea" is closely related to the way I think of things. I've been attracted to Penrose reasoning, but always felt that he tried it "the wrong way" too.

    As I see it the collapse is merely a subjective information update - it is not a problem in itself in my view. I do however think, that systems interaction with this logic, will see an emergent gravity like interaction.

    This view also suggest to me that the whole idea of starting with the "wavefunction" of the universe, makes no sense, because it doesn't represent a physical picture. I think that gravity and spacetime geoemtry is even related to interactions subject to this lack of objectivity, in that it's in the interaction between two pictures that gravity and geometry make sense. I don't think there is any objective state of gravity, or objective collapse. In this sense I feel Penrose attacks the interesting idea of a graivty-wavefunction connection in the wrong way. The idea of performing a measurement on the gravity field is IMO also not straightforward as the whole thing contains a self-reference.

    Note: This was my post # 1024!! :)

    /Fredrik
     
  5. Feb 15, 2009 #4
    If the wavefunction suggests that the particle takes every path and so is everywhere in superposition with everywhere else, then the local gravitational field of a particle suggests that the particle wavefunction has collapsed to a region. Or perhaps the gravitational field of a particle is also a collapse of a superposition of every possible field.
     
  6. Feb 16, 2009 #5

    Fra

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    The way I think of this, the relation between gravity and the collapse is more at the level of origin of inertia. If we think of a wave function collapse as an information update, there is more to that than just adding more information. If you add the plausible constraint that any system can only hold a finite amount of information, then unavoidably the wavefunction collapse is also followed by some kind of release of information as well, unless the systems information capacity is increasing, which is also possible, but is hardly a general case.

    It's somehow intuitive that two interacting systems, that interact in between them, and thus "exchange information" has a tendency to converge. Their disagreement will decrease. This is how I picture the simplest possible basis of how communication exchange leads to attractive forces. What remains is to find out exactly what force we get, and I think the formation of spacetime goes hand in hand with this.

    I sense I've got a reasonable conceptual handle on this, but it's still difficult. If you hold the idea that spacetime is an internal map a system have of it's environment, this map is certainly bound to respond dynamically to input. I expect something interesting to come out of that level. The concept of inertia is IMO strongly the related to the idea of constrained information capacity, because it's effectively already an "intertia" or universal qualifier of amount of information. I don't think the striking analogy is a conincidence.

    /Fredrik
     
  7. Feb 17, 2009 #6

    Fra

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    I think an interesting angle is to ask what is the physical basis is for the superposition itself - as I think of it, the superposition gets it's physical realization in the observers microstructure, therefor the limited information capacity of an observer also constraints what superpositions are possible, and should also induce some measure of the probability of combinations. This is should be highly unlikely to find an observer who maintains superpositions containint large tensions. Although possible, such an observer would be highly unstalbe and quickly resolve this by internal equilibration, or alternatively disintegration.

    But if one is considering the geometry of low total confidence, such as the geometry at the planck scale, then even the more weird superpostions suddenly should become reasonably probable, judged from an external massive observer (such as a human). But the wildness is still constrained by the low total complexity.

    So I think it's a relation between observer and observed, that is constrained by the relative complexity of the observer and the observed. This should put a constraint also on the relation.

    This is how I picture the connection to this discussion and to the evolutionary views. Where evolution of observes and particles, really could be (at least Ithink so) just the flip side of evolution of physical law. They are not in contradiction, I just see them as two opposite and complementary views.

    I'm not sure how you others think of this.

    I don't find the semi-classical attempts by fiddling with newtonian gravity and trying to combine it with decoherence very interesting, I think one needs to take a deeper grip on this. But I think the general curiousity in this direction is extremely interesting and motivated.

    /Fredrik
     
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