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Why do we say Objects at rest tend to stay at rest?

  1. Dec 21, 2013 #1
    Science wants to be correct,
    Every observable object on the planet is not at rest, we are all moving in space.
    Have any calculations been attempted to add a constant or variable to make calculations not
    start at rest, but at a certain motion?
    How can scientists reasonable say a statement that "a body at rest tends to stay at rest?"
    We can only say a body relatively at rest, but this is an illusion since all objects observable to us move in space at a rate which apparently is increasing, due to the current observation of the expansion of the universe.

    We would could only test what we observe, "a body in motion tends to stay in that motion until altered." We cannot assume "a body at rest tends to stay at rest." Because we cannot create at this time something on this planet at rest in the universe.

    -Albert Wiesbauer
  2. jcsd
  3. Dec 21, 2013 #2
  4. Dec 21, 2013 #3
    By having deteremined we are not at rest, we should rethink the idea of inertia. Maybe if something is set into space at true rest it would start to spin without having a velocity to keep it from spinning. Once velocity is added things could act different. Is there a way to disprove this?
  5. Dec 21, 2013 #4
    What you say about "true rest" seems to suggest that the universe has some absolute frame of reference against which to measure such a thing. Special and general relativity (and I suppose even Galilean relativity) say that such an absolute reference frame doesn't exist, only relative velocities have meaning.

    These ideas have served us well and there is nothing to suggest that an absolute frame of reference for the universe exists.
  6. Dec 21, 2013 #5
    Motion is always relative to some referential. There is no true rest. The rest in Newton's 1st law is taken as relative to some inertial referential.
  7. Dec 21, 2013 #6


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  8. Dec 21, 2013 #7


    Staff: Mentor

    This is not exactly correct either. Whether you are moving or at rest depends on the coordinate system that you choose. You can certainly choose one where you are at rest, and you can also choose one where we are all moving in space. Both are correct and the math works out correctly in either case, but there is no sense in which one inertial coordinate system is prefered over another.

    Yes, we can. Not only can we do this, it is easy to do. All we have to do is to define a given body to be at rest at some moment and build our coordinate system accordingly.
    Last edited: Dec 21, 2013
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