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Rotation and Gravity

  1. Jul 11, 2008 #1
    I do not have a great math background. However, the more I read about Relativity, the more it appears intuitive. If I understand correctly, gravity is not yet fully understood, at least not as well as is velocity, distance and time differences in different relative frames.

    Any example I have ever seen explaining why a clock (matter) experiences v t and d differently as viewed by another frame, has used examples of the clock moving at some speed compared to the other clock, in whatever direction: there is always a change in distance between the two somewhere in the example, and a difference in speed(v). I guess thats why they are in different inertial frames. So it appears relativity differences in v t & d require a change in distance between the compared objects?

    Does it make sense then if you imagine a large planet (say the Earth) spinning on its axis, and imagine a rock sitting on the surface at the equator. Now imagine you could burry a rock of equal mass at a location* half way down between your surface rock and the exact center of the earth. As the earth rotates, the surface rock is moving thru space faster than the burried rock from the burried rocks perspective, but there is no change in the distance between the two rocks.

    However, are not the two rocks experiencing centrifugal force a little differently than one another? Are they part of the same inertial frame?

    Also, From The burried rock's perspectice:Is not the surface rock moving faster and further thru space? Would the surface rock's clock move slower? Would its mass increase per E=mc2)? In a rotating sphere, Is there more and more energy with each layer? (a layer being all rocks an equal distance from the center, along th equater.

    Can you consider each "layer" of a rotating sphere as described above its own seperate inertial frame?

    Using these ideas, If you imagine as described above that there is more and more mass (energy) in each layer away from the center of a rotating sphere, then as a whole, is the sphere in a state of energy imbalance? Would the energy want to "equalize" towards the center, thereby "pushing" all the rocks (Atoms?)together? If this "pushing" force were greater than was needed to keep the sphere in an energy equalibrium, would the force "look" for other mass(energy) to bring (pull?push) into the center? If light (energy) passed by would this force try to "grab" it? If Another planet came too close? The Moon?

    Even without rotation, is there more energy at the surface of a body of mass than in the center, if you apply these ideas to each individual atom as being a frame of referance, rather than the layers above. If you start at the center of any object, there will be more and more atoms at each spherically measured distance point, or layer, (measured in all directions - measured points of each layer would look like the shell of a sphere, each layer one atom bigger in an outwrd direction) away from that center. I think this model would lead to the same as above.

    Any thoughts. Am i an iiot?
  2. jcsd
  3. Jul 11, 2008 #2


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    If Earth were not rotating, it would experience just as much time dilation. You know this and allude to it in your final paragraph, but I don't see how you address it. It pretty much negates the first 7 paragraphs.
  4. Jul 12, 2008 #3
    I meant to compare the results in the last paragraph the first 7 by saying even without rotation, same results per first 7 paragraph model. With rotation model, layers simply moved thru more space per the rotation.

    In non-spining idea, i imagined every single atom viewing another next to it from a different frame. if atoms continually move around, then they will see eachothers clocks moving slower as compared to their own, and since there are more atoms to be seen (by fewer atoms toward center) as moving with slower clocks out at the surface of the mass, this would create the unequal distibution of energy.
  5. Jul 13, 2008 #4


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    1] In a rotating sphere, atoms do X.
    2] In a non-rotating sphere, atoms do the very same X.
    Therefore, rotation is not a factor at all in whether or not atoms do X.

    Caveat: I am not suggesting that any of this is true, or even makes sense, so far I'm just examining the internal logic of your argument.

    Are you suggesting the atoms in the Earth are moving with respect to each other at relativistic speeds?
    1] What does 'atoms seeing each other' have to do with "creating" anything?
    2] ...let alone 'an unequal distibution of energy'? Whatever that is.
  6. Jul 13, 2008 #5


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    May I suggest a website where you can discuss perosnal theories more openly? "Bad Astronomy / Universe Today." (Ignore the title, it's a carry-over.)
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