Bill, in reply to your points above
3. If point one is correct, the continued presence of the geodesic is not required to keep the moon in orbit.
- According to GR, the geodesic exists regardless of the Newtonian explanation - an explanation that's almost a perfect fit to reality. Almost. The difference is that Newton, using the knowledge at his disposal, would be unable to explain certain observations, and would find himself in error when provided with extremely accurate measuring tools. GR has proven to be as accurate as may be determined by today's methods of measurement, on larger scales where Newton's theories are shown to be approximations.
4. The only way we can know that the Earth is still distorting spacetime is that other objects can assume Earth orbits, and there appears to be a “force” of gravity.
- The only way we can be convinced of the validity of GR theory is to compare objective reality with its predictions. GR theory has superceded Newton in this respect, even though the latter is simpler, and suffices for most everyday purposes (including local space exploration).
5. If the Earth could suddenly be removed from the scenario, the moon, according to Newton’s laws (and Kallog’s reasoning) would continue to orbit the spot where the Earth had been.
- According to Newton, the Moon would immediately shoot of at a tangent. According to Einstein, there would be a delay of just over a second.
6. Presumably, when the Earth was removed, spacetime would return to its original configuration; suggesting that some energy must have been required to maintain the distortion.
- Despite having declared that (I think) it doesn't, it does seem reasonable doesn't it. I find myself relying on snippets of info that I've gleaned over recent years, and I'm very much the unqualified non-authority. This particular snippet might interest you:
Gravitational Faraday Effect Produced by a Ring Laser - http://www.phys.uconn.edu/~mallett/Mallett2006.pdf
Using the linearized Einstein gravitational field equations and the Maxwell field
equations it is shown that the plane of polarization of an electromagnetic wave
is rotated by the gravitational field created by the electromagnetic radiation of
a ring laser.
