Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Space time curvature

  1. Sep 10, 2007 #1
    Due to mass Space time curves.
    Consider the case of sun & earth.
    Sun,since it is heavy will curve the space more than earth.isn't it?
    Then how come the sun and earth are being pulled towards each other with same force?
    The earth has to straighten the curve (caused by sun)first,and then has to curve it in opposite direction ,so that it can pull the sun towards it .Or the space time is curved between the two bodies?
    could anybody explain?
  2. jcsd
  3. Sep 10, 2007 #2
    Maybe this is just my misinterpretation, in which case someone will stop by to straighten both of us up, but: when you view gravity as nothing more than curvature of space, then what force is there between two masses?

    It doesn't make sense to me to say that the sun attracts the earth through a force, and at the same time the sun appears to attract the earth due to it warping spacetime.
  4. Sep 10, 2007 #3


    User Avatar
    Staff Emeritus
    Science Advisor

    This is correct as far as it goes. I think what you are probably missing is the idea that the Earth (for example) is essentially moving along a geodesic in space-time, and that it doesn't require a force to make an object move along a geodesic, it takes a force to make an object deviate from one.

    Thus gravity isn't a force in this geometric interpretation. Rather, objects with no force acting on them (no "real" force - gravity isn't a force in this interpretation) follow geodesics. They do this because that's the natural path for a body to take in a curved space-time.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook