Randomly selecting from an infinite number of choices

Discussion in 'Physics & Math' started by Nasor, Jan 20, 2009.

  1. Trippy ALEA IACTA EST Staff Member

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    Irrelevant, all that does is prove that the number chosen is finite, it does nothing to address the finiteness of choice.
     
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  3. Trippy ALEA IACTA EST Staff Member

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    I have come to the conclusion that this question amounts to "What is the smallest rational number between 0 and 1"

    The answer of course, is that there isn't one.

    What i'm about to say may send some of the mathematicians on this board into paroxysms of apoplexy (or laughter) but I have also come to the conclusion that the answer to this question is as follows:

    P(X=x) = δ

    And I have an inkling that I can prove it as well.
     
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  5. zanket Human Valued Senior Member

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    It does address the "finiteness of choice", by limiting the number of choices to a finite number.
     
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  7. Trippy ALEA IACTA EST Staff Member

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    No, it doesn't. All it does is demonstrate the tautology that a finite number is finite in length.

    If I have a choice of any number, of any length, I have a choice from an infinite number of possibilities, but it doesn't matter what possibility you choose, that possibility will still be a finite number.

    Your objection is meaningless.
     
  8. zanket Human Valued Senior Member

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    3,777
    But you don't have such choice. If you did, and it took you longer to choose "555" than "55", I'd have to wait forever for you to choose (I never get to guess your number), in which case the problem contradicts itself.
     
  9. Trippy ALEA IACTA EST Staff Member

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    No you wouldn't.

    Choice of a finite number is not the same thing as a finite number of choices.

    In order to choose 555 I fon't have to count 555.

    A number is a point, not a process.
     
  10. zanket Human Valued Senior Member

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    3,777
    Try choosing a number with 100 digits, and see if it takes you longer than choosing a number with 3 digits. Choosing a number is a process.
     
  11. Pete It's not rocket surgery Registered Senior Member

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    No, not so. the uncertainty principle tells us that there is no such point... at some scale, the coin's centre of mass is ill-defined. A fuzzy region, rather than a point.
     
  12. John Connellan Valued Senior Member

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    3,636
    This is true actually. A lot of people mistake heisenbergs uncertainty principle to mean simply that we can't measure with infinite precision, the position of things. What it really means is that there is no definite position at all
     
  13. quadraphonics Bloodthirsty Barbarian Valued Senior Member

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    Sure, supposing you accept zero precision on the velocity of said event. Which would seem to pose a problem for the car crash, which we would presume has a velocity of exactly zero...
     
  14. Nasor Valued Senior Member

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    6,231
    Oh, for crying out loud. There will still be a point at the exact of the region of uncertainty. The center of mass might not actually be at that particular point, but it's still a defined point that will fall randomly onto one of the infinitely many points along the ruler.

    Or like quadraphonics said, do a measurement that give you zero information about the velocity.
    Presumably the crash happened before you arrived to take the measurement.
     
  15. Pete It's not rocket surgery Registered Senior Member

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    No, I really don't think it works that way. But go further, down to the planck scale, and you'll run into more difficulties. There idea of infinite precision just doesn't seem to be built into the universe.
     
  16. Trippy ALEA IACTA EST Staff Member

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    It's sill totally irrelevant. The only thing you have proven is still that choosing a finite number from an infinite number of potential choices may take a finite amount of time.

    This does nothing to make the qiuestion meaningless of contradictory.

    The only thing it does do is potentially provide me with a piece of information that, if I know how to interprate it might provide me with information that allows me to establish an upper limit on the number you've chosen, however, that's outside the parameters of the original question.

    You're assuming that you're guessing after i've guessed, but it is possible to set the experiment up so that you don't know whether or not i've guessed until after you've guessed (effectively, we're guessing at the same time).

    Your objection is completely meaningless.
     
  17. John Connellan Valued Senior Member

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    3,636
    I think that mathematically what you have said is a paradox and still needs to be explained properly (although i thought I had by saying it was a countable infinity problem). However, trying to explain infinities using real life examples will always result in arguments which do not address the pure mathematical problem which you are trying to confront.

    For example, you said above there will still be a point at the center of the uncertanty, but even this can be disputed. There are no real points in this universe. Particles are limited by uncertainty but even space itself is limited by Planck volume ect!
     
  18. zanket Human Valued Senior Member

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    3,777
    Regardless who goes first, any number you choose will have been selected from a finite number of choices, which doesn't adhere to the problem definition.
     
  19. quadraphonics Bloodthirsty Barbarian Valued Senior Member

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    Just because particles don't have well-defined positions does not imply that a continuum of possible positions does not exist, nor that some such unique position could not be specified exactly.

    To even express the idea that a particle has a finite precision in its position requires you to first assume that it is possible, in principle, to distinguish between arbitrarily-closely spaced points in space (i.e., the domain of the wave function is typically the real line).

    There is a world of difference between what can be measured (definitely finite precision) and what can be specified (infinite precision).
     
  20. Trippy ALEA IACTA EST Staff Member

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    10,890
    No, it wouldn't. Choosing a finite number is not the same as having a finite number of choices.
     
  21. zanket Human Valued Senior Member

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    3,777
    That's not the reason it would. What guarantees that the number of choices is finite is that the time you took to choose the number was finite. The mere fact that you chose the number in a finite time means that your number of choices was limited to a finite number. Any choice is made in a finite time. Thus by making a choice you didn't adhere to the problem definition.
     
  22. Pete It's not rocket surgery Registered Senior Member

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    10,167
    Right... but we're entering the realm of models of the world, the realm of abstract mathematics... which was the main thrust of my earlier post, and is what I'd actually like to be discussing.
     
  23. Trippy ALEA IACTA EST Staff Member

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    No it doesn't - choosing one number from many does not require considering all numbers.

    No it doesn't, it only proves that I chose a finite number.

    At least, something that makes sense.

    No, because in choosing one number from infinitiely many, I only need to consider one number - the one which I am choosing.
    I do not have to count to it.
    I do not have to perform a process on it besides communicating it.
    I could have chosen any number higher than it.

    for example, if I chose.

    32465435165725132357461351324568735123213246573213135687213246574311354315746431313246343212465431324643032743465321643165431354631321

    A number I chose simply by mashing my numeric keypad

    I could just have easily chosen
    32465435165725132357461351324568735123213246573213135687213246574311354315746431313246343212465431324643032743465321643165431354631322

    32465435165725132357461351324568735123213246573213135687213246574311354315746431313246343212465431324643032743465321643165431354631323

    32465435165725132357461351324568735123213246573213135687213246574311354315746431313246343212465431324643032743465321643165431354631324

    Or:
    3246543516572513235746135132456873512321324657321313568721324657411354315746431313246343212465431324643032743465321643165431354631321547545165343213245354321654531537245637487454731646873241353567437346874645751643418673515486768767637435133676346876464687613576857489674546874346834356874541673553743168764646858645798674348435489746465432165467967846343134657489745643167986431165465346543416548678643456747864135456743246876541324586745646874354567865468766498465489657645197945634643573768465764354697644753768796464897465498766498674897634169744156464986734687645649674687768746876486796784646878976416576435468768574896486746557654654687654654651654654
    also a finite number, but one that is many times larger (also produced by mashing my keypad).

    The only thing that the fact that you're not still waiting for this post proves is that all of these numbers are finite.

    Id doesn't change the fact that they were selected randomly from a countably infinite pool of numbers (IE the set of all natural numbers).
     

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