----- Original Message -----
From: "Tim Maroney" <tim@maroney.org>
> Why? There are solutions of general relativity in which the universe is
> moving around the earth and the earth is standing still. Saying that the
> planets orbit the sun in ellipses is saying that the sun's frame of
> reference is preferred to the earth's. This preference for one frame of
> reference is apparently subjective.
>
This is a common myth, but it is untrue for two reasons.
The more relevant one is that choice of frames has no affect on which
objects are orbiting which objects. Even if we used an earth centered
coordinate system (where Earth was always at 0,0) we would still calculate
that the orbit of the Earth-Sun duo would be close to the center of Sun.
The second reason is that the theory of General Relativity states that there
is no prefered frame of reference among "non-inertial" frames. As soon as
you have accelleration (which happens during orbiting) all bets are off, and
there IS a prefered frame. The prefered frame is the only one that does not
require an unknown changing force to be applied to every object but one in
the universe.
This archive was generated by hypermail 2b30 : Fri Oct 12 2001 - 14:40:21 MDT