Thoroughgoing Machian GR says that *all* motion is relative, even
accelerated motion. Hence, a "spinning" wheel can be thought of at rest,
with the centrifugal forces on it being created by motion of the matter
beyond it. (Actually, not in the same sense as when charges start to
accelerate at a distance, for then there would be a time delay..) But
assume
that at least linear motion is relative and real to that extent. Then,
since
relative linear motions are "real" they can be used to make distinctions
between situations. Consider that a rotating body has actual relative
velocity vectors of parts of itself relative to any given other part! (For
example, each other point (if v << c) moves at v = -R cross omega,
where R is the connecting separation and not r of a circle etc.)
The magnitudes depend on omega, which is thus real per that consideration
(which does not invoke any mechanical or inertial effects.) I know,
rotation itself redefines that perhaps, but just taking the bare idea of
"relative velocity" and applying it to rotation, yields this result.
A paradox of understanding? A decent refutation of pan-relativism?
What say you?
(This belongs in several NGs for good discussion, so away with you,
mindless
anti-cross posters!)
http://tyrannogenius.blogspot.com
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