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Is Gravity a force?

  1. Nov 9, 2008 #1
    Is gravity a force?
    if its not a force as per GR,then why it is included in the fundamental forces and how we can combine remaining three forces with gravity(not a force)?
    if gravity is a force,why we are following GR which says gravity isn't a force?
  2. jcsd
  3. Nov 9, 2008 #2


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    It's a force in Newton's theory. It's not a force in GR. No matter what theory we use to describe it, it's definitely an interaction. So we should be talking about the fundamental interactions, not the fundamental forces.
  4. Nov 9, 2008 #3
    Gravity is just as much a force as the other three...sure, it has some different characteristics since it acts on everything, even spacetime, while the other forces are more limited...

    Nobody has figured out how to combine all four forces but superstring theory is trying...likely a new perspective, some different fundamental insights are required...like those that got relativity and quantum theory underway...
  5. Nov 9, 2008 #4
    Is it possible to combine other three forces with gravity even though gravity isn't a force? then this would be equivalent to finding Ether which doesn't exists? i mean, we are trying to find a solution for an invalid question?
  6. Nov 9, 2008 #5


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    it is a separate fundamental "interaction" in the sense that the curvature of space (which is related to the acceleration due to the force of gravity in a Newtonian sense) is caused by the presence of matter (and energy when you divide by c2). so if you don't want to say that some matter is exerting a force on some other matter, you can say that some matter is warping or curving space-time which causes (from the Euclidian POV) inertial or free-falling trajectories to bend. at least that's how i think of the interaction of gravity.
  7. Nov 9, 2008 #6
    None of them are forces. Not in the F=ma sense of freshman physics. Quantum mechanics, the realm of the "other three forces" is not a theory of force. It is a theory of superposition and strength of interaction. Newtonian "forces" are the macroscopic limit of field interactions. This phrase "four fundamental forces" is an oversimplification.
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