QM randomness...

Discussion in 'Physics & Math' started by Seattle, Jun 2, 2017.

  1. origin In a democracy you deserve the leaders you elect. Valued Senior Member

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    You are Reiku, aren't you. Welcome back once again.
     
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  3. Write4U Valued Senior Member

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    Because it has already been probabilistically determined. It still obeys causality, it's just that we can only experience one reality at a time.
     
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  5. Geon Registered Member

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    Isn't it an interesting idiom, probabilistically determined? You can slip a macroscopic coin, it can land a head or a tails, it is also said probability manifests the macroscopic scale - so can any one tell me the key differences between the probabilities that govern things on the macroscopic scale and those that govern the wave function of matter?

    Essentially, everything is supposed to have a wave function. Even me and you, we have wave functions, they are just generally regarded too dampened to measure - a type of natural quantum decoherence (which is similar to a collapse in the wave function, by natural means of entanglement and other various quantum mechanical processes. However, macroscopically-speaking, things behave deterministically with a causal order - despite it having probability fields surrounding them.

    These are very difficult questions, that scientists have been asking for a very long time. I come to understand my reality in a specific way . I am not sitting here without a reason, there are physical reasons which have led to my existence today. The sum of that history and the meaning and causality of that history cannot be described simply by the sum of my probabilistic configuration, I believe there is more to it than that - I believe reality is threaded in unusual ways we still cannot fathom. We only have an incomplete picture of quantum mechanics - and trying to make definite conclusions from it concerning vague concepts like this, is arduous.
     
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  7. Write4U Valued Senior Member

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    Perhaps they don't. The wave interference pattern in the double slit experiment is not caused by the particles themselves but by the Pilot Wave in which they travel.
     
  8. iceaura Valued Senior Member

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    Of course. It does.
    And we have rigorous mathematical models and the prospect of a corresponding theory to describe how.
    We don't. We live in a causally modeled macroworld. We live in a world in which approximations and heuristics and simplifications via "cause and effect" have proved, over millions of years of evolution, to be very useful to a contingency-limited brain. They work. So do "colors", so do the various mechanisms by which we see three dimensional objects via a two dimensional retina, the operations by which we register "time", and so forth.

    Our brains are teacups, the macroworld is a firehose of information. We have to handle things somehow.
    Nothing is more "determined" than the operations of the 2nd Law of Thermodynamics. They are based, rigorously and mathematically modeled, in probability and statistics - and this will support all the determinism your psychological comfort requires.
     
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  9. Write4U Valued Senior Member

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    And gravity binds us to the earth and makes us aware of solids and/or recurring patterns. All extant life today has learned how to handle things somehow. This is why they escaped natural (out)selection in the first place, we are all adapted to and adapting (or trying) to the current environment.
    But our future is beginning to have a touch of Uncertainty, as things get more chaotic. Cause and Effect is a double edged sword.

    But the exponential function is a mathematical certainty and it only allows for limited growth of anything in a finite space and when that space can no longer support the growth rate, growth must and will inevitably become zero . Which means two things
    a) we humans choose a safe and moral way to halt the growth rate. (reasonable)
    b) natural selection will do it spontaneously for us. (by any means)

    This does not mean the elimination of temporary growth, but in the end, the mathematics will demand for an increased death rate of our species. Our future is very uncertain, because of too many seriously dangerous variables. Our very complexity demands a comparable wisdom.
     
    Last edited: Aug 27, 2017
  10. Geon Registered Member

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    Normally, we consider the seat of fundamental physics as the quantum world - I asked a question:

    ''But can a deterministic world arise from a non-deterministic one?''

    You replied ''of course it can!''

    I ask again, can it really? Are you actually saying, from pure chaos you can have absolute order? This world around us, looks very ordered - even follows causal effects. To say, a system with laws can come from lawless, unpredictable - purely random configurations simply makes no sense to me. But that is just me.

    If we want to understand whether a quantum world is truly random, I doubt a wave function will tell us anything about that - instead, we need to look at the aspects of quantum theory that seem so bizarre, that they could in fact hold answers to these kinds of questions. What is non-locality when it is home? Is non-locality truly a non-physical connection of a system? Does it involve hidden variables?

    Until you can answer these kinds of questions, questions about determinism is silly. The most important aspects of quantum theory, the most mystic and conspicuous problems, we are yet to find answers; and these questions hold vital keys to our understanding of quantum behaviour - with possible hidden information about highly important quantum activity, anything is possible right now.
     
  11. Geon Registered Member

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    I'd also be careful about being zealous over randomness as well, when we have over 60 maybe over 100 fine tuning parameters today. To explain how serious this situation is, even Susskind has admitted, the situation is so serious, god may even be a proposal to explain it!
     
  12. Geon Registered Member

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    Also, can I make a dig on this statement:

    '' We live in a causally modeled macroworld.''

    What's that really supposed to mean? We haven't causally modelled a world and it quickly followed. The world is causal and so we developed models to help explain that.
     
  13. Geon Registered Member

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    Take a watch of this

     
  14. exchemist Valued Senior Member

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    But you are the only one speaking of "pure chaos". Nobody who says the world appears not to be fully deterministic would make any claims involving "pure chaos".

    The two great pillars of physical chemistry are quantum theory and statistical thermodynamics. Both of these triumphantly successful theories show that randomness, under the operation of the laws of physics as we understand them, leads to order. So we do not have "pure chaos". We have physical laws and we have random behaviour, together.

    I would add that chaos theory, itself a branch of mathematics, shows that the states of many physical systems evolve in radically different ways, depending on infinitesimally tiny changes in starting conditions. In theory one can predict the evolution of the system if one knows the starting conditions with mathematical exactness. But any tiny error or uncertainty in the starting conditions leads to wildly different outcomes. So in practice, the outcome is not determinable.
     
  15. Geon Registered Member

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    ''But you are the only one speaking of "pure chaos". Nobody who says the world appears not to be fully deterministic would make any claims involving "pure chaos". ''



    Then don't use that terminology - and yes, the claim is everything is random. The question is whether causality arises from pure randomness - you can't have one theory quantum mechanics which deals with random systems and find compatibility between the macroscopic world (which clearly) follows rules and regulations.
     
  16. exchemist Valued Senior Member

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    Well QM is not "pure randomness". It is a very exact representation of what can be defined about a system, which is a considerable amount, and what cannot be known, which is only some of it. Similarly, the random motion of molecules, which motion however obeys certain exact physical laws, leads to predictable thermodynamic properties of bulk matter.

    In my opinion you need to consider more deeply the laws, obeyed respectively in QM and Stat TD. It is the inherent order in the world introduced by these observed laws that creates predictable behaviour and thus cause and effect, surely? The element of randomness is manifestly not the whole story in the physical world. If it were, then indeed we would have chaos.
     
  17. Geon Registered Member

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    Right. I fact, I don't see randomness anywhere, in quantum mechanics, only systems giving limited information to us.
     
  18. Geon Registered Member

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    And some times, you need to look at the bigger picture to answer the smaller ones, which is why the cosmological constraints known as fine tuning parameters are very important to questions like whether our universe looks specifically designed.
     
  19. Write4U Valued Senior Member

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    A fern looks specifically designed. But it only employs the mathematics of fractality to create self-similarity.

    The very structure of spacetime and its properties make certain mathematical behavior patterns imperative.
    No designer is necessary for nature to function in accordance to certain mathematical rules. Mathematics is an inherent potential of the fabric of spacetime.
     
  20. Geon Registered Member

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    Please...

    You speak about the subject as if its as simple as that. Sure, we live in three dimensions, that is actually one fine tuning parameter. Do you know how many exist? Many.

    The statistics imply, the universe is not by a random chance of design. Whether you want to regard that as god, or some superintelligence, or an all pervading influence - whatever your definition, something set this reality in its very fine, sitting on the knife-edge existence of dozens of fine tuning parameters. Or maybe you are in the other group, who thinks some day some theory will explain it?

    I am not too sure about the first one and almost confident the last one is way out of our reach. You do extend this a bit further than just three dimensions.. you argue mathematics is part of nature itself, yes? I'd agree and so would Tegmark - and yes, it is a sign that things are more causal than what may appear, even on the quantum scale! To have not only microscopic laws and macroscopic ones, tells us that reality truly isn't random - in fact, it implies the world is dancing to an all-pervading influence, which we call the laws - which themselves, give rise to inexplicable fine tuning problems.
     
  21. Write4U Valued Senior Member

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    I agree, but perhaps it took a single random probabilistic event in the original chaotic beginning (inflationary epoch) to start a purely causal chronology. If we knew all the mathematics we could trace everything back to its causal origin. Unfortunately we don't have access to all the mathematical functions going back to the beginning from the present, even as we can look back in time at the macro scale.

    But once we have a deterministic causality, everything else from there becomes a mathematically deterministic chronology.
    As Tegmark says, "the universe does not have some mathematical properties, it has only mathematical properties"
    It's just the overwhelming amount of numbers (values) and equations that prevents us from tracing each individual interaction which, when combined, form our weather patterns and also formed the universe as we know it.

    We commonly refer to the unpredictable nature of weather patterns which seem chaotic, but in reality weather patterns follow the same deterministic function as everything else.
    It is our ignorance (lack of information) that prevents us from making accurate predictions
     
    Last edited: Aug 28, 2017
  22. Geon Registered Member

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    Why the inflation epoch? Even if there is such a thing, many scientists are now objecting to it because it leads to eternal inflation, another name for a mutiverse. For that reason alone, cosmology isn't a fixed science, we have read about inflation being the corner stone explanation, but not every one is convinced.

    It also depends on your model as well... are you one of those who thinks of a universe coming from a singularity? Because I can assure everyone reading this, we have made quite a number of developments away from singular theories. In fact, neither Hawking or Penrose who vigilantly defended the singularity theorems, no longer believe in them.

    Look, it's entirely possible there are pre-big bang models. I mathematically investigated one myself.

    What would that say about the universe being random ''at some scale?'' A pre-big bang phase is exactly what scientists are investigating to answer the causal problems of the big bang - many believe now, the big bang was not the beginning of time, just another phase of a universe.
     
  23. iceaura Valued Senior Member

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    We "causally modelled" a world and it didn't follow - it stayed as it was, with our causal models acting as useful approximations and valuable shortcuts.
    How did you come to decide that your modeling assumptions were properties of the universe rather than human thought? By what magic do you know how the world "is", even before developing your theories?
    The theory, the body of equations, describes probabilities - centrally. It forbids the acquisition of more information, and even the existence of such information, unless other basic assumptions and well-established physical theories are first discarded.
     
    Last edited: Aug 28, 2017

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