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Dose Randome exist?

  1. Apr 23, 2003 #1
    i am not sure if this is the right section to post this in but i think it may be the closest one.
    Is there such a time when something is absolutly randome?
    Last edited: Apr 27, 2003
  2. jcsd
  3. Apr 24, 2003 #2


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    Hm..well there are some effects, i believe, dealing with quantum mechanics and stuff which are random..we can calculate the probability of something happening but i think thats the best we can do
  4. Apr 24, 2003 #3
    I believe nothing is random AT ALL.
    Everything has a certain mechanism, but sometimes people find it too hard to try to understand how a certain thing happens (or maybe they can't for technical reasons, or sometimes the variables are too much to count), but nothing is random.

    I once put this topic on PF 2.0, i still remember most of the answers.
    Some said that randomness is not really available in nature, but there is chaos, and sometimes we missunderstad chaos for randomness.
    Other said that HUP shows that the motion of a paritcle is random since we can't know the particle's place and velocity (ie momentum) at the same time.
    Some answered on this idea that not knowing the velocity and place of the particle does not mean its motion is random.
  5. Apr 24, 2003 #4
    It really depends on how randome is seen weather it is not knowing the path of soemthing or the path of something is impossable to predict.

    ran┬Ědom ( P ) Pronunciation Key (rndm)

    Having no specific pattern, purpose, or objective: random movements. See Synonyms at chance.

    Mathematics & Statistics. Of or relating to a type of circumstance or event that is described by a probability distribution.

    Of or relating to an event in which all outcomes are equally likely, as in the testing of a blood sample for the presence of a substance.

    well the last defantion just complicates things.
  6. Apr 24, 2003 #5


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    Hmm... Interesting question. I am leaning towards the idea that random actions do not occur, but are instead deterministic events of sufficiently great complexity and unstability to make gathering enough information about involved factors near impossible.
  7. Apr 25, 2003 #6
    Even pure randomness represents a pattern, like entropy defining maximal disorder.
  8. Apr 25, 2003 #7
    Can you please define pure randomness, or maybe you mean the common understanding of pure randomness ?
  9. Apr 25, 2003 #8


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    Cant you just say that pure randomness is when uncertainty is infinity
  10. Apr 25, 2003 #9
    "pure" randomness=true randomness
    =maximal disorder
    =maximal uncertainty
  11. Apr 26, 2003 #10
    I don't know, it doesn't make sense to me !
    A think is either random or not (and i do not beleive in randomness anyway).
    How can something be 'pure-random' and something be random, but not 'pure-random' ?
    you said :
    Well i don't think so, cause there is no upper bound of uncertainity (is there ?), so there is no []imaximal uncertainity[/i], Right ?

    And, from your post before this one, you said :
    Which is somehow paradoxial, cause if it represents a pattern, it is not random anymore ! (is it ?)

    (I am sad that the confused smiley was deleted in the new forums, it was quite useful for situations like this one).
  12. Apr 26, 2003 #11


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    Well, "random" would be the casual form of random...the way we use it every day...you pick a marble out of a bag..you are randomly picking marbles, however im sure you would agree that this is not perfectly random

    "pure random" would be the theoretical random, and thats the definition we are trying to establish here...

    Ok...how about this...digits of e...seemlingly random, but there is a definite pattern to the way they were established(1+1/1!+1/2!+1/3!.....i think thats the way its defined..lol i forgot already) and pi, i think if u analyze the digits, and i dont know if they have, but i would think there would be about the same number of each digit, however the way it was found has a definite pattern(the equations used to calculate it)
  13. Apr 26, 2003 #12
    This is a personal opinion...
    I would define randomness in connection with a certain observer...
    It would be inverse proportional with the quantity of information we have about that "random" system...randomness=k*entropy...
    I believe randomness can't be 0...in any case...because in the case of a 3D object we can't have all the information it contains...just the information we can "see" through the surface it has...
    Last edited: Apr 26, 2003
  14. Apr 26, 2003 #13

    Pink noise would be "random," white noise, under my definition, would be "truly random."

    Try predicting the pattern of white noise. One can't, that's why I call it "maximally uncertain."

    The pattern of white noise is that it is unpredictable!
  15. Apr 26, 2003 #14
    The definition of randomness I have come to is this

    A complete inability to predict the outcome of an event. I.e. one outcome has the same probabilty of occurance as any other. Thus a single coin tos is totally random. A dual coin toss may be random depending on what you are observing. If order is important then HT and TH do not represent the same result and the event is random. If however order is not as important then the result of obtaining at least one head and one tail is twice as likely as as ant other result and so we can calulate an expectation value for the event.
  16. Apr 26, 2003 #15


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    But if you observe the coin carefully enough, and measure things like it's aerodynamic qualities, you can in fact predict pretty exactly how the coin will fall. It is not random, but a product of complex factors that make prediction difficult, but not a case of complete inability.
  17. Apr 27, 2003 #16
    what about radioactive decay.we can only give an expected time of decay, and a half life of an amount of substance. No matter how closely we observe an excited atom, or how much information we obtained from it, we cannot predict with certainty when it will decay. Take in place of the coin toss which I described earlier the decay of 2 identical particles, and bet on which one decays first. This randomness is in no way a result of us not knowing enough about the individual particle, but is inherant as predicted by quantum mechanics. Before anyone tries to reply to this, I do not want any comments on how Quantum mechanics is wrong unless you have studied quantum mechanics and have a better theory.
  18. Apr 27, 2003 #17
    In the case of a probability field with all the probabilities equal the entropy is maximum...so...as I have said...the randomness is maximum...but these probabilities depend on how much information an observer has about that system...
    For example...do you know the random numbers generator used on computers ? Actually it follows a simple rule (is something like x Mod 29...or something like this...) If you don't know the rule the numbers seem to be random...but if you know the rule...no more randomness...
  19. Apr 27, 2003 #18
    I totally agree on this.
    But some people may sart arguing saying that that the aerodynamics cannot be totally known, since they depend on the air molecules, and we don't know the place and speed (therefore momentum) of the air particle at the same time at any given moment (assuming we are welling to calculate everything so accurately that we would observe each air molecule around the coin).
    I would personalyl reply on people like those, suppose we were found as the universe started, we would be able to know the speed and position of each atom at that time (mainly depends on how you believe the universe started).
    Tracking all those enormous information, we would be able to know the position and speed (only depending on the data gathered at the universe begining) of any particle.

    I don't know if Greg would read this topic, but if he does i would really appreciate if he checks the database of PF2 for a similiar topic in the mathematics forum (it is not really old, so maybe it would be found in the second or third page), or maybe anyone that has the archive of PF2.
    Thanks in advance.
  20. Apr 27, 2003 #19

    If you went and measured the speed and position of every atom or particle at the start of the universe, where would you store this information and how would you calculate the time evolution of this system, as every particle would need at least another particle to store this information. And the 3 position coordinates and 3 momentum coordinates are as compressed as the information can get. Thus randomness in inherent in the universe because it is IMPOSSIBLE to know all this information at once.
  21. Apr 27, 2003 #20
    Don't take you as being a material thing.
    Just think of it as a soul.
    Or simply don't think too much about where it will be stored, maybe in another universe :smile:.

    (OK, my point is weak (like always !))
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