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The sun is incredibly massive object and it causes the space around it to bend. This causes the planets to pulled to the sun or the planets move in an elliptical path around the sun. But I don't understand how the curvature in space can cause the pulling or what cause the planets to move in elliptical path?

Samuel
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    http://www.youtube.com/watch?v=DdC0QN6f3G4 – Jold Apr 11 '13 at 04:21
  • @elfmotat Very nice! And thank goodness it is not that terrible rubber sheet analogy! Though to my eyes it looked like the straight path of the falling apple was slightly curved. Holding a pen to the screen I saw it was straight, so it must be some kind of optical illusion. Don't know if others are prone to this. – Michael Apr 11 '13 at 04:26
  • Yes. David Z. points to essentially same question. L. Motl answered it very well there. The OP may also want to look at http://en.wikipedia.org/wiki/Spacetime. – user12811 Apr 11 '13 at 04:37
  • @elfmotat: That's very very precise. Good for "no-math" GR introductory ;-) – Waffle's Crazy Peanut Apr 11 '13 at 04:45
  • @DavidZaslavsky: Hi David. There's another possible duplicate which is exactly a duplicate with an exception that it hasn't got any answers ;-) – Waffle's Crazy Peanut Apr 11 '13 at 05:12
  • @user12811 (and anyone else) If you agree that the question is a duplicate, just flag it as such. – David Z Apr 11 '13 at 15:57
  • @DavidZaslavsky what do you mean "flag it as such". click on "flag"? there is no "duplicate" choice, and clicking on close just is a vote for closing, which I would only use if the question were worthless. – anna v Apr 11 '13 at 18:45
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    @annav Voting to close is not just for worthless questions. On the close menu, there is an option to vote to close as a duplicate (or, if you don't have 3000 reputation, to flag as a duplicate), which is what you use when the question is good but just happens to already have been asked. The other close reasons are for when the question needs improvement. Remember, closing is often temporary! – David Z Apr 11 '13 at 19:29

2 Answers2

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As this is not closed as a duplicate I will try a simple answer, though the links in comments are adequate.

In Newtonian mechanics one has the planetary bodies which exert a force on each other.

In General Relativity the same planetary bodies distort the space geometry around them, rather than acting on each other.

The force concept is subsumed by the shape in space. If there are no masses then the space is undistorted. One mass distorts the space around it in a calculable way.

Two masses change in concurrence the space such that the trajectory they travel on follows the least resistance path in this distorted space. Calculations show a small deviation from the solution of Newtonian equations and the consequent ellipses, but important enough for satellite paths and navigation. The geometry is still elliptical,except that it is a path through space and not a trajectory at the end of a force field.

Community
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anna v
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  • Do you disagree that the question should be closed as a duplicate? – David Z Apr 11 '13 at 15:53
  • @DavidZaslavsky I agree it is a duplicate. I anwered because it was not being closed :). – anna v Apr 11 '13 at 16:05
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    It was not being closed precisely because people like you didn't vote to close it. ;-) Also, when someone posts an answer to a question, we (moderators) take it as a sign that the answerer thinks the question should remain open. – David Z Apr 11 '13 at 16:10
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Space "geometry"... seems to ignore real cause and effect. See this for another approach: http://metaresearch.org/cosmology/gravity/possiblenewpropertiesofgravity.asp

Glen Little
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  • The linked article displays a lack of comprehension about how general relativity works. the ADM formulation of relativity explicitly shows how the law of cause and effect corresponds to a relativistic spacetime. – Zo the Relativist Apr 14 '13 at 20:47