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Speed increases mass, which increases gravity?

  1. Jul 2, 2009 #1
    So if speed increases mass as it approaches c, does the added mass increase the curvature of space-time? The reason why this question is making me confused is because the mass is only increased to an outside observer. Could anyone clarify this for me.
  2. jcsd
  3. Jul 2, 2009 #2


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    Gold Member

    Correct. Relativistic mass does not contribute to the curvature of spacetime.
  4. Jul 2, 2009 #3


    Staff: Mentor

    The source of gravity in GR is the stress-energy tensor which has 10 independent components, only one of which is mass. So mass, by itself, is not the source of gravity.
  5. Jul 3, 2009 #4


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    Science Advisor

    In SR, there is no gravity, and mass does not curve spacetime.

    In GR, spacetime curvature is caused by the stress-energy tensor, whose components are frame dependent. The relativistic mass is one component of the stress-energy tensor in some frames, and so does curve spacetime. In frames in which there is no relativistic mass, this is made up for by changes in other components of the stress-energy tensor, so that the spacetime curvature remains the same regardless of frame.
    Last edited: Jul 3, 2009
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