🚀 go-pugleaf

metares@well.sf.ca.us (Tom Van Flandern) writes:

>     Well, I agree up to a point.  But we mustn't throw reason out the
>window.  If solutions do not give reasonable physical behavior, then
>something is wrong.

Tom, you haven't workd out the solutions, and you're using intuition
to determine what is "reasonable physical behavior" (nothing wrong with
that, we all do to some extent), so don't be too sure.  The something
that is wrong might be your assumptions.

>     ...
>     Now as I understand it, the Einstein's Equation is supposed to have
>solutions that will allow the nearly infinite matter density locality to
>halt a general expansion and remain flat.  But the condition of local
>spacetime depends only on the matter distribution in the universe, not on
>its motion.  Therefore we can make the same statement if the universe is in
>a state of general contraction: a nearly infinite matter density locality
>must halt the general contraction and remain flat!  I submit that goes
>beyond counter-intuitive into the unimaginable.

Not flat, not flat, not flat, but Schwarzschild ...  I know that the
curvature of the Schwarzschild solar-system spacetime is small at, say,
the earth's radius, but it's immeasurably larger than the curvature of
a homogeneous universe at a reasonable present-day state.  So you 
shouldn't quite call it flat.  After all, the whole issue is: Is it 
appropriate to use Newtonian gravity for the solar system, galaxy, 
gravitationally bound systms in general?  Any gravitationally bound
system is by its nature not in completely flat spacetime.

OK, onward.  Where I disagree with your submission is the statement
that the high matter density "halts" the general contraction.  It
doesn't, it just overpowers it, by virtue of its dominating curvature
(see above paragraph).  I think what you're trying to say is that in the
expanding universe, the local gravity counteracts the expansion, creating
a bound system, so in the contracting universe, what does the local 
gravity counteract?  The way I phrased that sentence should help show that
this is a non-issue.  A gravitationally bound system in a contracting
universe simply remains gravitationally bound, and can be treated with
Newtonian gravity.  (Or post-Newtonian approx. in the solar system, if 
you feel like splitting hairs.)

Eventually, when the universe contracts down to a size comparable to the
gravitationally bound ragion, funny things will clearly happen; but by
then the assumptions made about a small dense region in a generally 
homogeneous universe have long since become invalid.