Re: [asa] geocentricity

On Thu, 5 Jul 2007, George Murphy wrote:

> I'm afraid that I may get to be known as a nutty advocate of geocentrism
> (as distinguished from just nutty), but I have to point out again that
> in the context of general relativity there is NO way to show that the
> earth goes around the sun rather than the sun around the earth. A
> coordinate system in which the earth is at rest is just as good as one
> in which the sun is at rest & requires no superluminal speeds &c.

  I might be mistaken, but I don't think this is correct. Special
relativity means that all inertial (non-accelerating) frames of reference
stand on equal footing -- any one of them could equally be said to be the
one "at rest." But earth is in an accelerating frame of reference.
(Circular or eliptical orbits are accelerating frames of reference.) I
believe that even under General Relativity, one can do experiments to tell
the difference between being in an inertial reference frame (i.e. not
moving) and an accelerating frame of reference. (Maybe you know about
some alternative interpretation of GR of which I'm unaware.)

  Also, one might ask: If the earth isn't moving, how is it possible for
satelites to acquire velocity when they make a "slingshot maneuver" around
the earth?

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Received on Thu Jul 5 13:56:41 2007