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Opposite directions

  1. Sep 25, 2005 #1

    Avgiu

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    Can two objects that have no empty space between them move in opposite directoins?
     
    Avgiu, Sep 25, 2005
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  3. Sep 25, 2005 #2

    Doc Al

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    What if they rotate?
     
    Doc Al, Sep 25, 2005
  4. Sep 25, 2005 #3

    Avgiu

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    If there is nothing that separates the rotating objects, are they not attached?
     
    Avgiu, Sep 25, 2005
  5. Sep 25, 2005 #4

    Doc Al

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    They could be. But they can still rotate. Imagine two blocks stuck together. The system rotates about its center. So, one block goes left while the other goes right. (Momentarily.)

    What are you getting at with this question? (I don't see any obvious physics here.)
     
    Doc Al, Sep 25, 2005
  6. Sep 25, 2005 #5

    Avgiu

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    Is there empty space between a marble and the glass table it moves across
     
    Last edited by a moderator: Sep 25, 2005
    Avgiu, Sep 25, 2005
  7. Sep 25, 2005 #6

    Doc Al

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    I would say no, at least macroscopically.

    That's a much better example (of two things with no space between them moving in opposite directions) than my rotating object example! So I guess you answered your own question. Another example would be two things sliding across each other.
     
    Doc Al, Sep 25, 2005
  8. Sep 26, 2005 #7

    Avgiu

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    In first response your talking about a baton type of thing where one end is going against one way and the other is going another way. But you spoke of things sliding across each other. How can a thing slide across another thing without there being empty space, and if there is no empty space doesnt that change most of modern day physics?
     
    Avgiu, Sep 26, 2005
  9. Sep 26, 2005 #8

    Doc Al

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    I'm not sure what kind of answer you are looking for. It seems like you are hanging alot on the meaning of "empty space". You slide a block of wood across a table. Is there "empty space" between the wood and the table? Macroscopically, I'd say no; but microscopically, there's plenty of empty space. After all, most things are mainly "empty" space. The only real "contact" between the surfaces is at the surface irregularities. I'm not seeing the issue. (And I certainly don't see the impact on modern day physics!)
     
    Doc Al, Sep 26, 2005
  10. Sep 26, 2005 #9

    ZapperZ

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    This person also needs to clearly explain what is meant by an "object". By the time one gets to the extremely small scale, we have to invoke QM and all appearence of an "object" with definite spatial boundary is no longer valid.

    So from where I'm looking, it looks like the question in this thread is using some rules from one realm of physics and mixing it with another set of rules from a different realm of physics. Such an exercise seldom produces anything meaningful.

    Zz.
     
    ZapperZ, Sep 26, 2005
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