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Gravity and spacetime curvature. Have I understood it?

  1. Jun 23, 2015 #1
    When spacetime is not bent the two objects, red ball and blue ball, will move strait up the y-axis as they move through time. (Space is x and time is y).
    Spacetime1.png
    Now I've made the assumption that either a) All things want to move the smallest possible distance to the next point in time or b) all objects move 90 degrees relative to the rotation (Curvature) of the space in their coordinates. These two assumptions give the same result. As you can see in the picture below the blue ball is now heavy and has curved space significantly. Where the red ball is the time is now pointing a bit to the left. As the two objects move through time they will now meet in one point.
    Spacetime2.png
    Is this what gravity is or have I missunderstood it? If not I'd be really glad if someone could show me a 2d picture of spacetime and how it actually works.
     
  2. jcsd
  3. Jun 23, 2015 #2

    A.T.

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  4. Jun 23, 2015 #3
    But is spacetime really curved relative to the object itself? If I jump 1 meter up and down spacetime, in relation to me, is not going to change right? That video only makes sense to me if light or something travels next to a star or something and changes its path due to it actually traveling so far that the change in spacetime angle matters.

    Also that curvature is weird. Is the planet supposed to be at the bottom? How on earth is the curve spaced around it? I just cant picture it.

    Hm if I go in from another angle I perhaps can see the point. The planet makes, from the apples perspective, the next frame in time slightly bended a few degrees. Though this can't really be imagined from an outsider perspective.

    So, I don't think I fully understood just by watching those videos. I mean, I see why the ball is moving down but I dont understand the curvature itself.
     
  5. Jun 23, 2015 #4

    A.T.

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    Try the links in the video description of the second video (on youtube).
     
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