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Randomness refuted?

  1. May 2, 2009 #1
    I have heard that any type of true random behavior/variable in any system leads to true randomness within the whole system (as it quickly becomes disordered). If true, does this refute true randomness, as it seems there are at least some observed systems that do not display true randomness and are ordered?
     
  2. jcsd
  3. May 2, 2009 #2

    D H

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    Where did you hear this random nonsense?
     
  4. May 2, 2009 #3

    chiro

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    On the topic of randomness I would say that simply randomness is a label for our inability to decipher something.

    Take the topic of primes. When primes were first discovered most people would believe that primes are random possibly according to some distribution with certain moments.

    Of course nowadays there are plenty of formulas for generating prime numbers and they are deterministic in accordance to that formula.

    As our understanding of things progresses, the component of randomness slowly turns into one of understanding and not something with a distribution and a few predictable moments. I would even say the same thing about quantum mechanics in that more understanding is needed to help reform the randomness aspect into something more well understood.

    We also have measures for disorder and definitions for entropy but again these definitions fall back on an assumption that things really are random. Proving that something fits a distribution with certain properties does not really prove that something is 100% unpredictable: it just means that at the current time we are unable to decode the pattern or orderliness of the behaviour of some phenomena.

    Remember we are only very early in our stages of discovery. We have only got solutions for toy models in quantum field theory and our mathematical development is still in my mind very limited. For example we have calculus but we don't have powerful enough tools to simplify a great deal of infinite series that use more complex primitives like for example fourier series. Thats just one example and there are obviously tonnes more.

    Anyway thats just my 2c.
     
  5. May 2, 2009 #4
    1) It is not true that any random component of a system will necessarily lead to randomness within the entire system. For example, let "rand" be a random number between 0.1 and 0.5. Then the following statement is completely determined:

    int x = floor( 100.0f + rand);

    It's also possible for a small amount of randomness to result in a macroscopic change:

    int x = 100.0f * pow(rand, 100.0f);

    You can use the success of Newtonian physics as an example for reliable macroscopic results despite random internal parts. You can also use things like quantum tunneling, which make the quantum tunneling microscope a reality, or quantum entanglement, which make quantum computers a reality, as examples for where small amounts of randomness can be magnified to have larger scale effects.

    2) I personally agree with chiro, that the apparent randomness of quantum mechanics is simply due to a highly chaotic yet deterministic process occurring below the observable limit of technology. We know full well that statistics are effective means of making predictions from deterministic things that have too many factors for us to model all of them explicitly, so the success of quantum theory is in no way evidence for the universe being non-deterministic (since that is not verifiable evidence).
     
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