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Oct19-07, 01:54 AM
P: 1,480
Several of the comments re the speed of fields are not established by experiment - the speed of light in a vacuum is c, we all know that, but the speed with which a closed non-divergent magnetic field propagates in a loop of magnetic material is not readily explainable in terms of the field starting out at each pole of the energized magnet and meeting itself somewhere in middle - waves go from place to place - we do not know the mechanism by which fields make their forces felt at a distance -

It seems when physics needs to explain quantum entanglements and virtual photons the speed barrier is shunted to the side. In the case of gravity, it is usually assumed there is a graviton exchange between attracted particles - but gravity and inertia may be the result of global dynamics - the cosmological constant or, like expansion, an ongoing change that does not happen at one place and travel to another, but rather something that affects spacetime continuously. The curvature of GR may be the result of local mass interaction therewith, in which case it may not be meaningful to assign a propagation velocity to the curvature.