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From: rigney@uokvax.UUCP
Newsgroups: net.movies.sw
Subject: Re: Re: Parsecs - (nf)
Message-ID: <4721@uiucdcs.UUCP>
Date: Tue, 27-Dec-83 22:43:47 EST
Article-I.D.: uiucdcs.4721
Posted: Tue Dec 27 22:43:47 1983
Date-Received: Fri, 6-Jan-84 01:46:30 EST
Lines: 26

#R:tpvax:-13800:uokvax:12300011:000:1151
uokvax!rigney    Dec 26 11:58:00 1983

No, a parsec is the distance from  which  a  star  observed  from
opposite  sides  of Earth's orbit is seen to shift one arc-second
of parallax.  Not only does it depend on Earth's  orbit,  but  it
also  depends  on  the  measurement of an an arc-second, which is
arbitrarily (from a universal point of view) set at 1/1296000  of
a  complete  circle.   Poorly phrased, but you get the idea?  You
could use a parrad, for a parallax of one radian (A radian  is  a
universal  measurement,  pi  is pi everywhere), except this still
depends on the radius of the Earth's orbit.  And  you  can't  use
any other radius either, because there's no universal radius.

I say can't, but obviously you can use  such  a  measurement.   I
suspect  in  a  future  galactic  standard  there  would  be many
differing  local  standards  of  measurement,  and  just  a   few
universal  standards, based on powers of 2, times the fundamental
constants.   The  only  difference  in  universal  standards,  of
course,  would  be  scaling factors and names; that's why they're
called universal.

Anyone care to post suggestions?  Do we care:-?

	Carl
	..!ctvax!uokvax!rigney