Darren New <dne### [at] sanrrcom> wrote:
> Clearly, gravity changes an object's velocity.

  It only looks to us like it changes its velocity, again, because we
only see a 3D slice of space-time.
  This is not much different as when we see a movie of a car driving
towards the horizon: On the 2D screen it looks like its velocity is
continually decreasing, until it gets to an almost halt, even though
in reality the velocity of the car could be constant. This is because
a 2D projection of the 3D world loses information.

  Due to the principle of inertia, since there are no forces acting on
a free-falling object, its velocity doesn't change.

> If you define gravity *not* to be a "force", then
> you have to define "force" differently than Newton did (obviously), at
> which point I don't know what the definition would be.

  If gravity does not change the velocity of an object (because it doesn't
cause any acceleration on it) then there's no need to redefine the meaning
of "force". The only difference with Newton is that Newton assumed that
gravity is a force even though it isn't (well, not according to GR anyways,
if we can assume it's correct).

-- 
                                                          - Warp

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