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So, does God play dice with the Universe or not?

  1. Nov 1, 2012 #1
    Hi. I'm currently reading 'The Goldilocks Enigma' by Paul Davies. In it he attempts to explain some areas of Quantum Mechanics in laymans terms and writes...

    "Quantum randomness, by contrast, is irreducible, which is to say that quantum processes are in some sense genuinely spontaneous - without any specific cause."

    He later gives an example of virtual particles spontaneously appearing as a result of vacuum fluctuations. He claims that this 'randomness' was the reason Einstein hated quantum mechanics and declared "God does not play dice with the Universe".

    The book was written 2006. Are Paul Davies views above on 'quantum randomness' still valid?

    My question and thoughts about it are as follows...

    How do we know that quantum fluctuations are truely random and not instead the result of some other force or energy - The mechanism of which is still beyond our understanding.

    For example the chaotic flow of smoke rising from a candle is not 'random' but just impossibly difficult to calculate. Could this be true of quantum fluctuations but on an immense scale?

    To sum up my question is this...

    If quantum fluctuations are truely random and without cause how do we know this is true?

    Many thanks for reading this.
     
  2. jcsd
  3. Nov 1, 2012 #2
    Depends on interpretation.
     
  4. Nov 1, 2012 #3

    DrChinese

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    Davies' views are still valid, and I would call them generally accepted.

    It is *possible* that there is an underlying cause to random quantum behavior. However, if there is, it is non-local in character. That means that the cause moves faster than the speed of light c. So Einstein would choke on that.

    The reason we know that is because the random behavior of entangled particles is correlated. It should not be correlated unless there is some kind of hidden mechanism which can make changes instantaneously.
     
  5. Nov 1, 2012 #4
    We don't. All we can say right now is that we don't know that it isn't true.
     
  6. Nov 1, 2012 #5
    If a system depends on a few variables and we know all of them,
    the system can be explain exactly. It is a deterministic system.
    When number of variables go up and just one variable is lost,
    the system would appear as random to us.

    Following the above reasoning we can say quantum randomness is
    not truely random.
     
  7. Nov 1, 2012 #6
    Unless one of the variables is random.
     
  8. Nov 2, 2012 #7
    I merely have an interest in this, far from an understanding (let alone terminology).

    Thinking of the instantaneous correlation between "anti-correlated" particles I thought of the distance between them.

    Since any moment between the anti-correlated particles is perfectly correlated, I assume the distance (specifically length in this case) between them is perfectly orthogonal to the temporal/time dimension. If that's true the distance between the particles could be called a proper length (plane of simultaneity).

    I guess my question is it possible to spoil this correlation between "entangled" particles. If so how?
     
    Last edited: Nov 2, 2012
  9. Nov 2, 2012 #8

    DrChinese

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    This is circular reasoning, as you are essentially assuming that which you want to prove. If there is such an unknown variable, where is it? That is what Bell's Theorem addresses. Of course it is always possible NON-LOCAL hidden variables will be discovered, and that is what the Bohmian type theories assert. But there can be no local hidden variables.

    At this point, there is no evidence in favor of one QM interpretation over the other. So pick your poison: either locality or determinism must be rejected.
     
  10. Nov 2, 2012 #9
    One should also realize that Probability in QM would have never consistently worked if quantum world were truely random.
     
  11. Nov 2, 2012 #10

    mfb

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    It depends on the interpretation of "determinism". Many-worlds is local and has a deterministic evolution of the wave-function. You cannot predict "I will measure that", but that is impossible in all interpretations (including de-Broglie Bohm, as you cannot know the particle positions in advance) unless the amplitude of all other results is zero.
     
  12. Nov 2, 2012 #11
    Eh?:bugeye:
    That's like saying the kinetic theory would never consistently work if atomic motion were truly random
     
  13. Nov 3, 2012 #12

    A. Neumaier

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    Nonlocal is not the same as noncausal. Einstein was only against the latter. There are perfectly well-defined nonlocal and causal interacting quantum field theories in dimensions <4, where no informaltion can flow with a speed larger than that of light. And probably there are such theories in 4D as well, though we don't know yet how to construct these.
     
    Last edited: Nov 3, 2012
  14. Nov 3, 2012 #13
    Atomic motions in a gas are not random.
    There are too many particles (variables) with too
    many movements (more variables) in a gas makes
    it practically impossible to treat each particle individually.
    Instead we use a collective approach, such as volume of gas.
     
  15. Nov 3, 2012 #14

    Bill_K

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    Please give an example.
     
  16. Nov 4, 2012 #15

    A. Neumaier

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  17. Nov 4, 2012 #16
    I don't think that this can be said to be known. What might be said to be known is that certain preparations can't be modeled according to, say, Bell's formulation of a local hidden variable supplement to qm. So what does this tell us about whether god plays dice with the universe or not? Nobody can say for sure. But since experimental violations of Bell inequalities have been satisfactorily explained more parsimoniously than by the assumption of nonlocal propagations, then local hidden variable explanations remain a possiblity ... just not in the mathematical form that Bell sought to associate them with standard qm.

    Referring to esmarelda4's OP, to say that "quantum fluctuations are truely random and without cause" is a statement that is entirely devoid of physical meaning. Because there's simply no way to ascertain what the deep causes of a macroscopical quantum experimental phenomenon might be.

    Experimental physics deals with, and only refers to, the behavior of instruments. If that behavior is unpredictable in some sense, then in that sense that behavior is called random -- and that's the only thing that the term 'random' refers to ... as far as science (in this case, experimental quantum physics) is concerned.
     
    Last edited: Nov 4, 2012
  18. Nov 4, 2012 #17
  19. Nov 5, 2012 #18
    This is all speculation. Does any of it answer the OP question? No. Is the OP question even scientifically answerable, ie., is it a physicially meaningful question? I don't think so. In other words ... in my opinion, it's just nonsense. I mean, I think these sorts of questions are quite ignorant, stupid, silly ... and however else one might denigrate them.

    What do you think, StevieTNZ?
     
    Last edited by a moderator: May 6, 2017
  20. Nov 5, 2012 #19
    I would say "quite popular" is more accurate. Of course, most physicists do not care at all about the question if the randomness is genuin or not or so, and so one can expect that they follow what has been teached.

    But there are others who care and spend at least some time on quantum foundations. Their opinion about this is less certain.

    The randomness is clearly not irreducible - one way how to reduce it is well known, de Broglie-Bohm theory. One may not like it, but this is another question. Even if one prefers an interpretation where randomness is genuinely spontaneous it is clear that this is only a metaphysical decision to prefer such an interpretation.

    As Einstein himself, as Bell quoting him have been unhappy that the problem Einstein has had with quantum theory has been reduced in the public opinion to this unfortunate quote about God playing dice. The problem was much more about giving up realism.

    Yes, it can be - and de Broglie-Bohm theory gives an explicit formula for a possible underlying deterministic equation.

    We cannot know in principle that something we observe as random is not simply deterministic but chaotic.

    But in case of quantum theory the situation is much simpler, here we already know that it can be deterministic.
     
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