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I Can mathematics disagree with the real world?

  1. May 7, 2016 #1
    Are there "things" mathematics describes that can't exist in the real world; things mathematics says can exist but are actually impossible to ever exist in the world we live in?

    Also, are there things that do exist in our world that mathematics says can't exist? The obvious answer to me is no, but I am far from informed on any of this.

    Your insights are greatly valued, to me.
     
    Last edited: May 7, 2016
  2. jcsd
  3. May 7, 2016 #2

    Drakkith

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    How about a tesseract?

    I'd say no as well, but I'm not math expert.
     
  4. May 7, 2016 #3

    jim mcnamara

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    I think you are confusing some things: mathematics and models. When I was in college a very long time ago, one the faculty members there said, "Current aerodynamics models say that bumblebees cannot possibly fly." Well, bumblebees do fly. So where was the problem? The bumblebee model used was constructed wrong.

    Nothing to do with math. It's like blaming the messenger for the contents of the message.

    The math in the model simply followed the "directions" given. Which were wrong.

    [edit]http://www.snopes.com/science/bumblebees.asp
    cites a minor excerpt from a book, based on a faulty model as the reason for this bit of nonsense.
     
  5. May 7, 2016 #4

    phinds

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    As far as is known, the "infinity density" area at the center of a black hole, which we call a "singularity" is CALLED a "singularity" because although the math says it exists, it is believed that such a thing cannot exist physically. The assumption is that this, like the example Jim gave, is because our math model is wrong but it does point out a definite case where it appears that the math describes something that is physically impossible. The fact that this particular model does not properly describe physical reality does not mean that it's invalid math, just that it is applied incorrectly in this case.

    It was all summed up many decades ago by Korzibsky: "The map is not the territory"
     
  6. May 7, 2016 #5

    fresh_42

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    Personally I'm convinced that something as easy as a circle does not "exist" in "the real world". Whenever you try to show me one I will refer to the next electron microscope. Did you know that mathematics counted as a Geisteswissenschaft (science of spirit) in former times rather than a science of nature? And although mathematics nowadays is widely used as the language of science of nature it is still closer related to philosophy. It is a framework of logical conclusions within a given frame of conditions. "The real world" has nothing to do with it.
     
  7. May 7, 2016 #6

    phinds

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    Good point, and another great example of the map not being the territory, the model not being the reality. A model (math) is ideal, not real. The confusion only arises at all because math does SUCH a great job of describing reality (particularly when you don't probe down to the 20th decimal place)
     
  8. May 7, 2016 #7
    There are solutions to the Einstein field equations that give a geometry of the universe, which as far as we know, does not describe the actual universe. Mathematical predictions about the real world must be backed up by actual observation.
     
  9. May 7, 2016 #8

    jedishrfu

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  10. May 7, 2016 #9

    mathman

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  11. May 7, 2016 #10

    Mark44

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    Lots of things exist in mathematics, but not in the "real" world, the world that we perceive, which is four-dimensional, with time being one of the dimensions. In mathematics we can work with vectors of three, four, five, ten, or more dimensions (including an infinite number of dimensions). The fact that something doesn't exist in the real world is of no consequence to mathematicians.
     
  12. May 8, 2016 #11
    Thank you all so much for your answers. They are much appreciated.
     
  13. May 10, 2016 #12

    Stephen Tashi

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    That's an interesting question. How do we identify the mathematical existence of something in the real world? We are allowed a lot of arbitrary choices. For example if a person says "That gate is rectangle", he needs to identify something about the gate as its vertices and something about the gate as its edges. Another person might look at the same gate and say "That gate is a random process with two states, 'open' and 'closed'. So a given real object can be regarded as different mathematical structures - and, of course, as given mathematical structure can be applied to more than one real world object. Given that there is so much freedom in matching up mathematical concepts with actual things, it would be surprising to me if a mathematical object exists that can't be matched up to something in the real world if we are given enough freedom in doing the matching-up. If you put restrictions on how the matching-up is done then that's a different question. For example if you insist that "point" and "edge" are defined as places were two planar pieces of sheet metal meet then this greatly restricts what real world objects can be identified as mathematical objects involving points and edges. By contrast, if we are given complete freedom in defining points and edges, we could say that a "point" will be a person, or a color, or a voltage value.
     
  14. May 12, 2016 #13

    Svein

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    "Mathematics can never prove anything. No mathematics has any content. All any mathematics can do is -- sometimes -- turn out to be useful in describing some aspects of our so-called 'physical universe'. That is a bonus; most forms of mathematics are as meaning-free as chess."

    - Robert A. Heinlein
     
  15. May 13, 2016 #14

    chiro

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    Mathematics largely looks at consistency in a variety of contexts.

    The "pure" mathematicians focus most of their energies on such consistency and they look to create and resolve paradoxes with the existing body of mathematical knowledge.

    This consistency need not reflect all forms of consistency found in nature (you will find that developments - "major" developments in mathematics actually consider something thought to be impossible or inconsistent and then find a way to actually make it consistent and eventually make some sense of it).

    You have to question whether nature is consistent before you can answer your original question.
     
  16. May 16, 2016 #15
    There are no things that Mathematics claims cannot exist. In fact, Mathematics can formulate some things to claim its existence that do not exist in reality.
    Each process may have infinite results that chain to infinite more results. So the probablity of anything is never 0. Anything existing can always be proved for its possibility of existence.
     
  17. May 16, 2016 #16

    phinds

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    He did not ask if there is anything that math CLAIMS cannot exist, he asked if there are things that math DESCRIBES that cannot exist in the real world, and has been shown over and over in this thead the answer to that is yes.

    I have no idea what this means.
    I have even less idea what that means.

    That is demonstrably incorrect to the point of being ridiculous.

    That seems like a tautology. "Things that exist, exist". Yep, they sure do.
     
  18. May 16, 2016 #17

    Stephen Tashi

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    That result hasn't been shown.

    What has been argued is that if you match up certain simple mathematical concepts to things in the real world (like "point" and "surface") then more complicated mathematical objects that are defined in terms of those simple concepts do not exist. The failure of mathematics to describe a real world object is only a failure within a certain context - namely a context where you have stipulated a particular way in which mathematics succeeds in describing certain real world things.
     
  19. May 16, 2016 #18
    Math can be used to describe negative quantity, such as in the case where my friend gives me an apple on the condition that I will give him an apple tomorrow.
    Mathematically until I give the apple to him, I am the owner of -1 apple, but -1 apple does not actually exist.
     
  20. May 16, 2016 #19

    fresh_42

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    Math describes a ball which cannot exist in the real world. That has been said more or less.

    This argumentation is in the opposite direction. It wasn't about whether a model can't be set up to describe mathematically a real world object which I agree would be a matter of context.
    Nevertheless, a mathematical ball cannot exist in reality. There is no smooth object that can be made out of a finite number of molecules. In any context.
     
  21. May 16, 2016 #20

    phinds

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    I am dumbfounded that you would say so. I give the following argument (basically, what has already been said in this thread)
    1. Mathematics can describe a perfect circle consisting of an infinite number of points in an extremely precise geometrical relationship
    2. Such an object cannot exist in the real world.
    So do you reject this argument? If so why and if not, how can this not be called an object that math describes that does not exist in the real world?
     
  22. May 16, 2016 #21

    symbolipoint

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    "Can Mathematics disagree with the Real World"?

    Yes! Further, Mathematics can also be misapplied.
     
  23. May 16, 2016 #22

    Stephen Tashi

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    You haven't made an argument. Are you saying that a "point" cannot exist as a real world object ? Or are you saying that particular real world things exist that are "points" and the particular arrangement of those material things that forms a circle cannot exist ? Are you saying that such an arrangement cannot exist because of some physical law ? Or are you merely saying such arrangements can't be created by a particular manufacturing process ?

    In modern mathematics there is no requirement that a "point" represents something in physical space.
     
  24. May 17, 2016 #23

    phinds

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    I'm saying that matter is quantized and ideal circles are not so a mathematical circle cannot be formed in the real world.
     
  25. May 17, 2016 #24

    lavinia

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    In many theories in physics e.g. classical mechanics, the theories of relativity, string theory, quantum mechanics .... space is modeled as a smooth manifold. So why can't a perfect circle exist in a smooth manifold?
     
  26. May 17, 2016 #25

    phinds

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    I don't get how a smooth manifold gets around the fact that mass is quantized. Look, I'm not arguing that math doesn't do an amazingly good job of describing the real world, but I continue to believe that mathematical ideal are exactly that ... ideals ... and cannot be realized perfectly in the real world. I don't see that as a problem, just a fact.
     
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