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General Relativity

  1. Oct 12, 2014 #1
    If a rocket takes off from upper part of earth then it will have to pass the curvature(known as gravity) experiencing gravity which we also experience in reality.But if a rocket takes off from lower part (say antarctica) and moves straight downwards then it would not have to pass the curvature caused by earth mass and so it should not experience gravity. But we know gravity is all around earth.
    What will you say to save the THEORY!
     
  2. jcsd
  3. Oct 12, 2014 #2

    Nugatory

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    Would you by any chance be thinking of one of those pictures that shows the earth as a ball sitting in depression in a stretched sheet? If so, you should put that picture out of your mind, as it very misleading.

    The curvature in general relativity is curvature of four-dimensional space-time, not three-dimensional space. We humans aren't very good at visualizing four-dimensional shapes :) so you won't find any good pictures. However, the thing you need to know is that the curvature is the same in all directions heading out from the earth - the standard solution (google for "Schwarzchild metric") for the gravitational field of a massive sphere like a star or a planet is spherically symmetric, meaning thatthe curvature at any given point is a function of the distance from the center of the earth but not the direction.
     
  4. Oct 12, 2014 #3

    Matterwave

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    A quick way to refute your argument is to note that in space there is no "down" or "up". So Antarctica happens to be what we call "south", there is nothing in space to distinguish it as special. There's no "upper part" or "lower part", the Earth is just a sphere (to first approximation), and as far as gravity is concerned, the Earth is the same from any which way you look at it (again, to first approximation).
     
  5. Oct 12, 2014 #4

    Dale

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    The theory does not need saving. Misunderstandings about a theory do not constitute a challenge to the theory, merely an educational opportunity for the person with the misunderstanding.
     
  6. Oct 13, 2014 #5
    actually yes pictures are very misleading.
     
  7. Oct 13, 2014 #6

    A.T.

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  8. Oct 14, 2014 #7
    theory of relativity cant be visualized actually but can be only understood in a very simple form..Its complicated version is very difficult to undestand.
     
  9. Oct 14, 2014 #8

    Nugatory

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    Keep at it.... The hard part isn't the theory, it's recognizing the unconscious classical assumptions that we make about how the world works so that we can retrain our intuition.
     
  10. Oct 14, 2014 #9

    A.T.

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    Yes, some simple scenarios, which involve just 2 of the 4 space-time dimensions can be visualized in one diagram. Others require multiple diagrams.
     
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