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Space-Time gravitational field problem

  1. Mar 1, 2009 #1
    Space-Time is deformed from a uniform gravitation field to one that is compressed inward so as to form a curvature. That curvature is uniform and can be understood as a series of decreasing diameters of circular field lines. If that is the case, then why are the planet's orbits elliptical and not circular? They follow the curvature of the gravitational field lines, which are circular. Are the orbits elliptical due to a composite interaction of an infinite number of celestial bodies in the universe? Are the elliptical orbits a sign of the cosmological constant or perhaps if not taken into consideration the illusion of the mysterious dark matter, yet undetected? If the elliptical orbits are a result of the motion of the celestial bodies, then why was this overlooked or skirted around (no pun) in the General Theory of Relativity?
  2. jcsd
  3. Mar 1, 2009 #2
    That is not the case; perhaps your questions are based in confusion between modern knowledge and oversimplified cartoons of modern knowledge. Nothing in GR nor Newtonian gravity would say that orbits have to be circular in the first place.
  4. Mar 2, 2009 #3

    Jonathan Scott

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    You're using a model where gravity is the curvature of space as you move through it. This isn't right; most of the visible effect of gravity is due to an acceleration which is experienced even for slow-moving or static objects, and can be considered as being due to the curvature of paths in space with respect to time. For a spherically symmetrical situation, the curvature of space is of the same magnitude, but the rate at which something moves through space is typically tiny (as a fraction of c) compared with the rate at which it moves through time, so the dominant effect is the curvature with respect to time.
  5. Mar 2, 2009 #4


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    Elliptical, and precessing orbits emerge naturally in GR. You have been misinformed.
  6. Mar 2, 2009 #5


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    Last edited by a moderator: Apr 24, 2017
  7. Mar 3, 2009 #6
    This statement seems self contradicting.... there is flat space (without gravity, as in special relativity), a uniform gravitational field (as in the equivalence principle, from an infinite plane of mass) and then typical curved spacetime when gravity from finite sized masses is present.
    Last edited: Mar 3, 2009
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