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Which side?

  1. Oct 18, 2010 #1
    I was just gong to learn general relativity(not with maths) but with some very basic tutorials given over internet. I also watched the animated series of general realtivity.

    Everywhere i see,matter bends spacetime( a fabric of spac and time woven ). And when there is matter than this spacetime is curved, warped.

    And many tutors give the idea of the trampoline net . You keep heavy object(A) in the middle of the net.
    Then the tempoline net is curved. And other body (B) kept over the edge of trompoline net wll fall towards the heavy object(A). This idea is very fascinating and enjoyable.
    But this experiement is done in earth. The gravity of the earth pulls the body (A) . so the trompoline net is curved downward, so the body (B) falls to the heavy object (A)

    But in the universe there is no meaning of up and down.
    so I am confused ,how the space is being curved. Let us suppose a heavy object (A)
    in Universe I have uploaded two pics. In the pic I have given name upside and downside.
    Can anyone say how the process is ging to happen.
    Because space is everywhere surrounding over the planet an the chances of space curving are equally probable in any direction. I am going mad ain this topic.
    Or my way of understanding is wrong. I will give million ,billion thanks(not dollars::rofl:)
    to that person who makes me clear. Advance thanks

    Attached Files:

  2. jcsd
  3. Oct 18, 2010 #2


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    Hi Hyperspace2! :smile:
    The "falling" doesn't matter, all that matters is the curvature.

    Using a hat, say, instead of a trampoline, it makes no difference whether the hat is the right way up or the wrong way up … the curvature is the same.

    The geometry of space-time is decided by the "straight lines" in it, and whether they stay parallel, or get further apart or closer together.

    Hit a billiard ball hard, and it will follow the same curve (approximately) whether it's on the upper surface of the hat the right way up, or the hat the wrong way up.

    The purpose of the trampoline analogy is to show how two balls side-by-side will move closer to each other as they get nearer the centre … the way gravity actually acts on the trampoline is not meant to mimic the way it acts in space-time. :wink:
  4. Oct 18, 2010 #3
    Could we think like this , space somewhat pushes the body of lower mass to the body of higher mass- ( i didn't say this I copied this from Dr. Micho Kaku in his video on you tube.)
  5. Oct 18, 2010 #4
    Did Eeinstine had a very very clear picture or he could imagine the spacetime curve .
    Or he had some confusion as Like newton had confusion for he couldnot explain how gravity works.
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