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No HUP, a universe without unknowns?

  1. Sep 13, 2006 #1
    If the universe did not act in accordance with the HUP would it display different properties to the universe we know and love? A large number of people have difficulty accepting the underlying concept of the universe being undefined but what would be the alternative? Would the universe be vastly different if all properties could be known at time (t)? If so, how would it be different? Would Hawkings work be drastically deficient? Would the universe be completely comprehensible and without mystery? I’d appreciate any feed back you might care to share with me.
     
  2. jcsd
  3. Sep 17, 2006 #2
    undefinable is not the same as undefined, just as indeterminable is not the same as indeterministic. Indeterminability is simply a reflection of our epistemic limitations (which is what the HUP is telling us), it is not necessarily a reflection of any underlying ontic randomness in nature.

    Even if the HUP did not exist as a limitation to epistemology, there is no way any agent within a finite universe could know all the details of that universe. Let's say the universe comprises N particles. To record the positions and momenta of each of those particles in 3 dimensions at one moment in time would require 6 real numbers, that's 6*N real numbers for a system of N particles. Leaving aside the problem that a real number might not be fully specifiable with a finite number of digits, where/how do you store those 6*N real numbers if you only have N particles in your universe? It cannot be done.

    Best Regards
     
  4. Sep 17, 2006 #3
    David Deutsch argues that a classical universe would soon unravel due to
    classical chaos.
     
  5. Sep 17, 2006 #4
    "unravel"?

    who "ravelled" it in the first place? :eek:
     
  6. Sep 21, 2006 #5
    Suppose a system of 2 particles, one matter of mass 3, one antimatter of mass 2. Then we would have 12 real numbers to store. Suppose next that the 2 particles form a superposition (no reason for annihilation due to asymmetrical masses), such that 10 of the 12 real numbers are stored as imaginary numbers of the form (i). So, perhaps it can be done, at least in theory, but we need to expand the "real" number to also include the "imaginary" ?
     
  7. Sep 21, 2006 #6
    Interesting idea. But if the objective is to know everything about the universe (I assume that's what the OP meant by "completely comprehensible and without mystery"), how do we achieve such an objective by having 10 of the 12 numbers stored as imaginary numbers in a superposition of quantum states? How do we get access to all 12 numbers?

    Best Regards
     
  8. Sep 23, 2006 #7
    I think we can only have such knowledge mathematically, since by definition science = uncertain knowledge.
     
  9. Sep 23, 2006 #8
    How do you get access to the information mathematically?

    Best Regards
     
  10. Sep 24, 2006 #9
    As I see it, it seems clear that humans cannot access complex information in totality, thus we must abstract (break down) each of the 12 numbers individually as "units" of conception. Then we must build them up again mathematically via a process of integration (not a sum, but an integration such as used in the calculus). The two processes (abstraction + integration) form a mental dialectic and the end result is a "concept" (here, knowledge of the 12). Thus, concept formation is basically an applied mathematical process, all that exists can be measured. In the case here, we deal with two entities that exist (a 3-mass matter and a 2-mass antimatter). Are we saying it is not possible that the quantum superposition that may be formed can be explained mathematically ? If not, why ?
     
  11. Sep 24, 2006 #10
    It's a question of information content vs storage capacity. The information needed to specify precisely the state of a particular system exceeds the information storing capacity of the same system. The problem is exacerbated by feedback - if you postulate increasing the number of degrees of freedom by suggesting multiple possibilities of superpositions of states, you are at the same time multiplying the amount of information that needs to be stored for that system (if the system is in one particular superposition of states rather than another then that is another set of physical properties of the system, in addition to the basic information on position and momenta of the particles, which needs to be encoded into the information we are storing for that system). In the end, the more degrees of freedom you postulate in order to create more information-storing capacity, the more information you need to store in order to specify which state that system is in - you cannot win.

    Best Regards
     
  12. Sep 24, 2006 #11
    I view that the system is in ALL of the required superpositions at the same time (one of the strange but true results of QM if that theory is true), so I think I am still in the game if QM is still on the field.
     
  13. Sep 24, 2006 #12

    DaveC426913

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    It sure would. In fact, it would be much, much shorter to list the things that are the same (for example. if atoms didn't exist, we wouldn't have to list all the things in our universe that are dependent on atoms).

    I do not think that HUP is a detail, to be tacked on to the workings of the universe. I think that you literally could not build our universe at all without it as a fundamental building block.
     
  14. Sep 25, 2006 #13
    The question being asked is whether "all properties could be known" if the HUP did not exist.

    Saying that the system is in a superposition of states does nothing to enable us to know what those states are.

    To "know what those states are" would require more information than could be stored using the same states as information storage. You can't win.

    Best Regards
     
  15. Sep 25, 2006 #14

    DaveC426913

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    You are makig the assumption that everything must be known about the universe simultaneously. There is nothing to say that you can't take a piece at a time and know everything about that piece.
     
  16. Sep 25, 2006 #15
    if you do this, you are assuming that the piece you knew about yesterday, which you now no longer know about, has not changed since yesterday. If it has changed, then all you ever know is bits of the universe, you never know the whole picture (and you can't put the bits together to make a picture if the bits have changed since you knew about them)

    Its a bit like trying to assemble a picture of a crowd of moving people by taking random close-up thumbnails, and then sticking the thumbnails together to make a large panorama - it is possible that you could end up with 1,000 thumbnails of the same face.....

    Best Regards
     
    Last edited: Sep 25, 2006
  17. Sep 25, 2006 #16

    DaveC426913

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    None of which is disallowed.

    Again, there is no requirement to know all of the universe at one moment. You can choose an arbitrarily large or small piece, such as one cubic parsec or one cubic metre, and know everything about what's going on in that space.
     
  18. Sep 26, 2006 #17
    If you read the OP carefully, you will see that there indeed is a requirement to know all the universe at one moment. The original question was whether
    and whether the universe would
    knowing "a bit of the universe at time (t1)" and knowing "another bit of the universe at time (t2)" and knowing yet "another bit of the universe at time (t3)" does not satisfy the requirement to know "all properties at time (t)", neither does it satisfy the requirement to render the universe completely comprehensible and without mystery.

    Best Regards
     
    Last edited: Sep 26, 2006
  19. Sep 26, 2006 #18

    DaveC426913

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    Conceded.

    Don't see how this one follows.

    There is no reason why I could not understand everything within a one metre cubic volume completely comprehensively and without mystery.
     
  20. Sep 26, 2006 #19
    I agree. But knowing completely one cubic metre volume does not give you complete knowledge of the universe, does it?

    Best Regards
     
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