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Information Paradox?

  1. Dec 30, 2006 #1
    As far as I know, net information content in the universe is constant. How about this:

    A child draws a simple skeleton of a house connected to another house with a pipe and draws a similar pair of houses right next to them with a fallen tree between the two houses. The second pair of houses has an antenna on the external face of the right house.

    This drawing is supposed to represent a neighbourhood or a street, but when a chemist looks at the drawing, he sees an organic reaction with two closed 5 membered rings (bond line representation), where the tree represents the arrow.

    Nothing has been added to the drawing, but it represents a neighbourhood and an organic reaction at the same time. The information has increased without anything being added to the original drawing. Isnt this an information paradox?
     
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  3. Dec 30, 2006 #2

    russ_watters

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    What about all the molecules that were broken apart to provide the energy for the child to make the drawing?
     
  4. Dec 30, 2006 #3
    Disagreed.
     
  5. Dec 30, 2006 #4
    Consider the universe once the drawing is completed. In principle (classically) you can measure the microstate: where every atom is, and its velocity. This is the final information content. You could also have done the same before the drawing. The two microstates must contain exactly the same amount of information because (in principle, by the deterministic nature of the laws of mechanics) knowing the initial microstate is completely sufficient to deduce the final microstate, and vice versa. Besides, in the situation you describe, the chemist obtains no new information anyway because in his context the child's message is just random noise.
     
  6. Jan 1, 2007 #5
    So, the information content in the universe is not constant? How so?
     
  7. Jan 1, 2007 #6
    The chemise, however, can see both the drawing as a neighbourhood, and as a chemical reaction. Where is the random noise? They are two different interpretations of the same drawing. The information derived from it however, changes from observer to observer. Where is the inconsistency?

    Wishing everyone a very happy and prosperous new year to all.
     
  8. Jan 1, 2007 #7
    What about them?
     
  9. Jan 1, 2007 #8
    Interesting thought. First of all, don't assume that information in the sense of information theory as corresponding exactly to intuitive ideas about information.

    Information theory quantifies the information in a signal (analog or digital).

    If you like, the resolution of your paradox is that the chemist's brain contains more information then the child brain. The childs perceives two signals: the visual information and the information his memory provides. The chemist receives 3 information signal, in this sense.

    Also, it is not true that the "total energy of the universe" is constant, because this quantity is not defined. Information is much less understood, and so your assumption that the total is constant is not even a question we can ask (yet).
     
  10. Jan 1, 2007 #9

    russ_watters

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    They represent a net decrease in the information content of the universe.

    Btw, that's what the 2nd law of thermodynamics says. The information content of the universe isn't constant, it is decreasing.
     
  11. Jan 1, 2007 #10
    Imagine I pull scrabble letters from a bag and write down whatever they spell. Perhaps I will obtain the sentence "everest is the highest mountain", and think that I have pulled information from the bag, but I would be mistaken to think so. I could just as easily have obtained "everest isthe smallest mountain" or "as djhfkajshdf kjbasdfkjhzskdfh". Realising this, I know that the sentence contains no information, no matter how it happens to appear.
     
  12. Jan 1, 2007 #11
    I agree with cesiumfrog, the information that you are considering is cultural it has no definitive meaning, it means what your culture attaches to it. Its like you take a pure thing like a perfectly natural number 666 and immediately attach conotations based on your culture.

    The other information contained would be deducible to a highly intelligent alien with no cultural bias, things like how hard the human pressed, what materials humans use for writing, traces of human DNA on the paper etc..etc..
     
  13. Jan 2, 2007 #12

    disregardthat

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    Yeah, I don't think the information sent depends on what is written. It depends on the person observing it and how he interpret it.
     
  14. Jan 2, 2007 #13

    Q_Goest

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    The only information needed to represent the drawing is 'information' about the position of every particle in the simple drawing. That information is not a house or a chemical reaction. It is the information regarding the particles' position/momentum/etc... in the simple drawing. There is nothing intrinsic about the positions of those particles such that they represent a house or a chemical reaction. They don't represent anything, a person's mind is needed to interpret those positions as symbols which can represent something else.

    When observed by a child, the child's mind interprets the symbols she sees on the page, such that the position of some set of particles in the child's brain results in the child thinking "house".

    When observed by a chemist, the chemist's mind interprets the symbols he sees on the page, such that the position of some set of particles in the chemist's brain results in the chemist thinking "chemical reaction".

    The position of the particles on the paper hasn't changed, thus there is no more information needed to describe the simple drawing. However, in order to create two different interpretations, two different sets of particles that are not part of the drawing must be created to interpret the symbols seen by the mind.

    A single person could also interpret the drawing in multiple ways, but in that case, the configuration of that person's mind must also have different configurations for each interpretation.
     
    Last edited: Jan 2, 2007
  15. Jan 2, 2007 #14
    So does information here mean the position of all the molecules present on the drawing or what we can deduce from processing the drawing?

    And since we can see the drawing because of the light reflected off of the drawing, is light here be the signal and the brain just the processor of the signal?
     
  16. Jan 2, 2007 #15
    And when the child draws the drawing, isnt the child coding information on the paper in the form of different colors? The chemist can decode the encoded information to a greater extent even if that wasnt the initial intent.
     
  17. Jan 2, 2007 #16
    If that is true, then the information recieved is greater than the information sent. The child only drew the house, but the chemist saw the house and the reaction.
     
  18. Jan 2, 2007 #17

    russ_watters

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    Could you guys please read my post #9. All of what you are discussing is irrelevant.
     
  19. Jan 2, 2007 #18
    That may be so, but with regards to your post: (since it seems "well known" that the total information in the universe is supposed to be conserved) do you think you should give a reference to support your contradictory assertion?
     
  20. Jan 2, 2007 #19

    disregardthat

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    Not everyone understands your post, and you did not explain yourself further, making your post 'just' another one in this thread. To me it gave no meaning. And probably not to everyone else here, since they also are discussing
     
  21. Jan 2, 2007 #20

    Q_Goest

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    Let's clarify what "information" means. From Wikipedia:
    http://en.wikipedia.org/wiki/Physical_information
    In the case of the OP, I think we should limit ourselves to classical information. Because although quantum information may be applicable, it isn't necessary to understand why the question isn't a paradox. For the sake of clarity, and because I'm no expert in QM, let's just consider the particles in the 'drawing' to be Lego blocks. Some of the Lego blocks are white, others are black, and together they form a picture. The analogy should be clear enough.

    The information needed to describe the picture now consists of what color Lego blocks are at each point. There is no other physical information which is contained within the drawing. The drawing doesn't contain information about a house or a chemical reaction. The information is only the location of the Lego blocks.

    Where I feel the mistake is being made is in assuming that the drawing is a representation of something, such that the representation is yet another bit of information. It's not. The representation of a house is 'seen' by the child, such that the subjective experience of the house is had only by the child who must have additional 'Lego blocks' that correspond to that subjective experience. Similarly, the chemist has a subjective experience of a chemical reaction, such that the subjective experience of the chemical reaction is had only by the chemist who must have additional Lego blocks in his head to correspond to that subjective experience.

    I'm not sure what exactly you had in mind here, Russ. I think you meant that the interpretation of the drawing of the house or chemical reaction represented a decrease in the information content because the drawing could be 'reduced' to a single concept. If that's not what you meant, please clarify.
     
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