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I Newton on absolute motion

  1. Jul 22, 2017 #1
    An interesting subject that was getting off topic from another thread… https://www.physicsforums.com/threa...me-dilation-imply-spacetime-curvature.919181/

    Note: Newton was not alone in this. Rene Descartes stated that the problem with relative motion is that every particle in the universe would require an infinite number of relative motions to all the other particles in the universe. I don’t know whether or not he viewed velocity as a “quantity of motion” as it is well known that Newton did.

    Newton was acutely aware of the inability to identify this state.

    "Hitherto I have laid down the definitions of such words as are less known, and explained the sense in which I would have them to be understood in the following discourse. I do not define time, space, place, and motion, as being well known to all. Only I must observe, that the common people conceive those quantities under no other notions but from the relation they bear to sensible objects. And thence arise certain prejudices, for the removing of which it will be convenient to distinguish them into absolute and relative, true and apparent, mathematical and common." -Isaac Newton

    Newton says that common people view time, space, place, and motion as relative. His view is that this is incorrect (prejudices to be removed). Newton puts forth his arguments six ways from Sunday here…

    Last edited: Jul 22, 2017
  2. jcsd
  3. Jul 22, 2017 #2


    Staff: Mentor

    Did you have a question?
  4. Jul 22, 2017 #3


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    Not sure what you are questioning in my side comment, in that what you post is in complete agreement with it, and the source you quote is also the source from which I became first aware of this fact.
    Last edited: Jul 22, 2017
  5. Jul 22, 2017 #4
    Thanks Dale. You’re the best. I was wondering about that when I started the thread. I’ve seen people here say things like “that is getting off topic, you might want to start a new thread for that” so I did not know whether or not a question was required when doing so. Thank you for clarifying that.

    The question I was having was regarding how it could be that Newton says he contradicts Descartes, yet they seem to be in agreement on their views of absolute motion.
  6. Jul 22, 2017 #5
    I see. I didn’t get that, from the way you worded your original post. The way you worded your original statement made it seem like you were kind of mocking Newton for having a dumb idea, or something along those lines. You say “he argued for the notion of absolute rest, even though ,..” The “even though”, sounded like a preponderance of evidence to the contrary , (and “six ways to Sunday” comment) sounded to me like “What a dummy. He thinks one thing, even though the evidence clearly indicates otherwise.”

    Thanks for clearing that up.
  7. Jul 22, 2017 #6


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    Those comments were meant to caution against interpreting Newton with modern biases, trying to underplay what he clearly argued (gravity is a force, free fall is not inertial motion) simply because he understood the facts that led Einstein in a different direction. I offered this as another example - though he thoroughly understood the inability in practice to determine absolute motion he would have argued against the modern consensus view of the principle of relativity - that there is no such thing as absolute motion.
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