Re: Sig Figures and tides

[David Bowman <David_Bowman@GEORGETOWNCOLLEGE.EDU>]

Regarding Herb's comment:
...
> In space everything is in relative motion. Although it is much simpler to
> describe the sun and the moon as celestial objects that are relatively still
> with respect to the earths motions,  there is nothing wrong by believing
> that the earth is motionless and everything else in space is in motion.
>
> Gottlieb from New York City
> (Where the sun rises in the East and sets in the West )

There might not be anything practically wrong with such a perspective for
a practical prescientific description, and there is nothing morally wrong
with this description either.  But there *is* something scientifically
wrong with it if it is to be used to describe the motions of objects
farther than about 27.48 AU from the earth's spin axis.  The rotating
coordinate system in which the earth's surface is at rest has a
cylinderical coordinate singularity at this distance from the rotation
axis, and it cannot be used for distances greater than that.  (Objects
greater that this distance travel at speeds greater than c in this
coordinate system.)  Such a situation *is* a real problem for a proper
scientific (i.e. relativisitic) description of the motions of distant
heavenly bodies.  Even Neptune and Pluto are in this forbidden region--
let alone all the Kuiper belt objects, all the stars (other than the sun)
and interstellar gas and dust clouds, all the galaxies, all the galactic
clusters, all the superclusters, all the quasars, all the inhomogeneities
in the cosmic microwave background, etc.

David Bowman
David_Bowman@georgetowncollege.edu