Re: is free, open source software ethical?

In article <pkpus3h71jihk1l4pldj329qvatj7ifj4d@[EMAIL PROTECTED]
>,
 Steve Schafer <steve@[EMAIL PROTECTED]
> wrote:

> On Wed, 05 Mar 2008 18:02:11 -0800, Ron Garret <rNOSPAMon@[EMAIL PROTECTED]
>
> wrote:
> 
> >To say that the sun revolves around the earth is very badly wrong in
> >fundamental ways.  To give just one example, if the sun revolves around
> >the earth, what is it that keeps it moving in a non-straight-line path?
> 
> First, let me say that I'm on your side in this discussion. Second, let
> me point out that this is actually a bad example. ;-)
> 
> What you're saying is true only if you restrict yourself to Newtonian
> mechanics. In his theory of general relativity, Einstein showed that
> _all_ reference frames are equivalent, even non-inertial ones.

If all frames of reference are equivalent, how does one distinguish 
between an inertial frame and a non-inertial one?

> (Special
> relativity, by the way, deals only with inertial reference frames.)

That's correct.  But just because general relativity extended the theory 
to non-inertial frames that does *not* mean that all frames (inertial 
and non-inertial) are equivalent.

> So, to answer your question, from a (simplified) relativistic point of
> view, if we take the motionless earth as our reference frame, what keeps
> the sun (and everything else in the rest of the universe) moving in a
> non-straight-line path is the curvature of space-time induced by the
> mass of the earth and the mass and momentum of the sun (and everything
> else in the rest of the universe). The apparent non-Newtonian motion is
> the result of the non-Euclidean geometry of space-time.

OK, two more questions:

1.  The earth is not a perfect sphere.  It bulges at the equator.  If 
the sun revolves around the earth and not vice versa, how do you account 
for this bulge?

2.  Notwithstanding this bulge, the earth is a very close approximation 
to a sphere.  And yet the motion of the sun around the earth is not 
spherically symmetric.  The sun not only revolves around the earth every 
24 hours, but it also oscillates vertically (that is, along the sun's 
axis of rotation around the earth) with a period of approximately 365.25 
days.  How do you account for this?

rg