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Macro object based on QM

  1. Mar 24, 2010 #1
    Does the notion that a mechanical resonator following the laws of quantum mechanics imply that a similar logic should be used to understand micro and macro events? If there is no border, then why should the logic be different? In other words, if macro events are based on QM, yet they are deterministic and causal in description, then can we not surmise that quantum events (although not determined in principle) are likely based on the same kind of logic that allows for macro consistency. If there is no border, then the logic should remain consistent. What do you think?
     
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  3. Mar 24, 2010 #2
    In other words, causal and based on tit for tat logic, but without true randomness, only unpredictable in principle and in practice. Maybe, the process of decoherence is a causal one based on available variables that can not be reached, or realism is actually present all along.
     
  4. Mar 24, 2010 #3
    Sure, it does seem to imply that. But there can be no scientific evidence either way. Inferences from logic will have to do, but they aren't testable. There's been tons written about that question. You are right that there can't logically be a macro / micro divide - we can prove that.
     
  5. Mar 24, 2010 #4
    Interesing. I know the position of Prof. Brian Greene on this matter. He stats that whilst we think that the macro world is determined and classical, it actually isn't, it just appears that we can make accurate measurements - but in reality any 'accurate' measurement of the macro world by our standards is actually a gross approximation/estimation. So I think that's where the logic you proposed breaks down - the macro world ISN'T determined in description, it just SEEMS that way because of our everyday experiences and our ability to make measurements that seem accurate but are actually just approximations.

    That's his position taken from 'fabric of the cosmos'.
     
  6. Mar 24, 2010 #5
    Well, take the uncertainty principle, and input an object with a mass of 25 kg into it, let's say we like to know its speed with a certainty of 0.00005 m/s. That's knowing the momentum with 0.000125 certainty.

    Let's divide that dirac's by that: 4.21828651 * 10^-32 accordingly google calculator.

    Well there you have it, every day life objects measured in reasonable accuracy have an uncertainty in position orders of magnitude smaller than the size of a proton. That's because they are ridiculously heavy and thus have a ridiculously high momentum meaning that we don't really need to worry.

    As soon as things get a lot less momentum, the uncertainty effect starts to appear visibly.
     
  7. Mar 24, 2010 #6
    It's not simply that we have uncertain knowledge of what the true speed of the object is though. Objects do not have a precise defined speed at a fundamental level, except instantaneously in certain special situations. There are very strange and important philosophical consequences to this, even if it isn't screwing up any calculations for engineers.

    Essentially QM says that none of the properties we ascribe to objects/particles (location, momentum, polarization, etc) exist persistently. Since this is the case, it is reasonable to question whether any of these properties can be considered basic, essential, or intrinsic to the objects we ascribe them to. If particles don't have defined locations at all times then having a location can't be a requirement for being a particle. If particles don't have momentum at all times... Repeating this could reasonably lead to the conclusion that our classical space-time properties do not represent fundamental reality - none of them is essential or persistent. You could reasonably question whether or not location and momentum etc can even be considered "real" in the strictest sense, if they do not correspond directly to fundamental properties but only appear as imperfect macroscopic approximations. Of course, we don't have any other options, so we have to still speak in terms of location and momentum etc.

    It's very mind blowing stuff once you start to really understand it (not that you don't understand it).
     
    Last edited: Mar 24, 2010
  8. Mar 24, 2010 #7
    To be honest, it helped me when I started to realize we should view it the other way around.

    A particle cannot have a location. A location can have a particle or not. And it just happens to be so, that for the most part there are identical amounts of particles, or at least approximately, but not necessarily. Particles don't 'move', some locations hold particles, or they don't. Interpreting it as if particles don't hop to from location x, to location y. But rather location x housed a particle, and in the next moment x no longer does, by y houses a particle (which just happens to have very similar properties to the one at x) kind of removes a lot of headaches for me.

    Also, I understand this like ****, it was yeeeaaars back when I realized physics was awful and I quit studying it just to not having to deal with—cry—linear algebra any more.

    Edit: The Heisenberg thing was just to show that once you increase mass beyond subatomic levels, the dirac's constant essentially becomes neglectibly small, and with it the effects of indeterminacy.
     
  9. Mar 24, 2010 #8


    Thanks for the perspective. To me the approximation of the macro scale seems so consistent and logic based in a way that makes me think for all practical purposes it may as well be deterministic. But, I see your point, if the approximation breaks down into uncertainty when applied to the micro level, then how can QM be similar in logic. Macro is an accurate description of approximation, whereas micro is an accurate statistical description of an approximation. It seems to me they should both be based on an approximation, as there is no boundary. So, maybe both are based on a similar animal of logical description, yet one is accepted as deterministic due to consistency in the approximations, and the other is due to constrained randomness.
     
  10. Mar 24, 2010 #9
    Sounds right to me. What blows my mind is that even when you get down to individual electrons you are still dealing with "macro" approximations that have no persistent casual properties.

    There are two main ways to look at the determinism issue. You can just say that Newton misled us and physics isn't deterministic - randomness in nature is fine if that's the best we think we can get. You can also say that the goal of physics is to uncover the causal (deterministic) mechanisms that the physical world operates on. Either way, the answer can't be determined by experiment. And of course there's a lot more to that argument too.
     
  11. Mar 24, 2010 #10

    Pythagorean

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    Is wetness a property of two or even three water molecules? No, it takes a macro scale of molecules to have a consistent body of behavior. Try to observe a water molecule and you will lose it (not just because it's small, but ts subject to reacting, phase-change and a bunch of other dynamics.)

    But the ocean, as an ensemble of particles, has reached a much steadier state.
     
  12. Mar 24, 2010 #11
    I think of wetness as a type of qualia, like pain, so I think this brings in new variables. Rather, if we accept the notion that there is no border between micro and macro scales (this is not to say we don't see differences on each scale), then we must conclude the same logic is inherent in both two or three water molecules and that of a larger ensemble (ocean). I think it comes down to emergent behaviors when we reach larger scale phenomena, but the larger scale is dependent on a consistency in the micro events. In other words, we can't say the macro behavior does what it does without the support of micro phenomena. (All of the properties involved in the making of a cake are separate and distinct, but then an emergence develops between all parts when baked that can't be accounted for in the separate ingredients. However, we can't say the final product of a baked cake is not based on all of its distinct parts and conditions interacting - sorry for the poor analogy). Obviously one or two water molecules can not show emergent properties that a large body of water can, but if there is no border, then they are completely compatible and in sync (in principle). Therefore, the same principle of logic applies, it is just expressed differently on different scales of size. In light of this, I wonder if classical logic is just a mask of QM, and it does not reason well with me that QM is truly random if no definitive distinction is made between micro and macro phenomena. I think this logic can be extrapolated to the notion of the macro scale being so consistent and continuous, and with no border, we must look more closely at what it means to be random on any level.
     
  13. Mar 24, 2010 #12
    I think of wetness as a type of qualia, like pain, so I think this brings in new variables. Rather, if we accept the notion that there is no border between micro and macro scales (this is not to say we don't see differences on each scale), then we must conclude the same logic is inherent in both two or three water molecules and that of a larger ensemble (ocean). I think it comes down to emergent behaviors when we reach larger scale phenomena, but the larger scale is dependent on a consistency in the micro events. In other words, we can't say the macro behavior does what it does without the support of micro phenomena. (All of the properties involved in the making of a cake are separate and distinct, but then an emergence develops between all parts when baked that can't be accounted for in the separate ingredients. However, we can't say the final product of a baked cake is not based on all of its distinct parts and conditions interacting - sorry for the poor analogy). Obviously one or two water molecules can not show emergent properties that a large body of water can, but if there is no border, then they are completely compatible and in sync (in principle). Therefore, the same principle of logic applies, it is just expressed differently on different scales of size. In light of this, I wonder if classical logic is just a mask of QM, and it does not reason well with me that QM is truly random if no definitive distinction is made between micro and macro phenomena. I think this logic can be extrapolated to the notion of the macro scale being so consistent and continuous, and with no border, we must look more closely at what it means to be random on any level.
     
  14. Mar 24, 2010 #13
    sorry for the double post!
     
  15. Mar 24, 2010 #14
    Macro 'objects' seem to me as much a construct of consciousness as time and space. The open quetion, imo, is how and why a phase space becomes 4D spacetime with macro objects in it.
     
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