From: metares@well.sf.ca.us (Tom Van Flandern)
Subject: Re: "Modeling" the Expanding Universe?
Organization: Whole Earth 'Lectronic Link
Date: Thu, 28 Jan 1993 16:05:11 GMT


schumach@convex.com (Richard A. Schumacher) writes:

> If one adds two test particles to the universe, the general expansion
> does NOT by itself cause the test particles to move apart.  Subsequent
> movement of the test particles depends on their mutual gravity and the
> gravitational or electromagnetic forces imposed on them by other
> matter/energy in the usual, non-cosmological ways.

     If the matter density is uniform, then the pair of test particles
increases its mutual separation due to the appearance of new space between
them, although both stay put in space.  Their motion in response to forces
is superimposed on that cosmological "expansion."

> Distant objects will in general move away from the test particles,
> because the distant objects inherited their velocity from the big bang
> and continue to move with that velocity (slowing due to mutual gravity,
> to which the test particles add trivially).

     Distant objects do not move through space at all, much less slow due
to the gravity of other objects.  Since the universe is supposed to be
homegeneous and isotropic on the large scale as seen by every observer, in
what direction could a "slowing" possibly act?

> One can say that space itself is expanding, but this expansion does not
> drag particles along with it; it might be better to say that the
> expanding distribution of original matter/energy creates new space as it
> expands.

     We agree there is no drag.  Particles don't move through space, and
don't get dragged anywhere.  They stay in place.  In the meantime, the big
bang explosion is continually adding more space between them.

> A big, misleading flaw in the "expanding balloon" or "rising loaf"
> pictures is that added test "particles" (dots painted on the balloon,
> raisins stuck into the loaf) WILL move away from each other.

     The analogy has its intrinsic limitations because the expansion is
into a specific dimension.  The big bang does not postulate that the
universe expands into a fourth dimension of space.  The expansion results
from the continuous creation of new space out of nothing.

> Right?

     Our views are converging, but apparently not yet fully converged.


and sbs@weyl.bu.edu (Stephen Selipsky) writes:

> nothing weird and nonlinear happens; the Solar system just gets crushed
> as all that external matter crashes in.  "The fall doesn't kill you, it's
> when you hit the bottom".

     If all of space is uniformly contracting when the matter density is
uniform, and the only exception is a spot of nearly infinite matter
density, the stress-energy is surely higher there than elsewhere.  Why
would this operate to *nullify* an ongoing general contraction?  The sign
is wrong.

     The extra space is supposed to be continuously created out of the big
bang.  Why does the new space that tries to appear in, e.g., the solar
system get suppressed so that it never appears at all, or appears somewhere
else?  -|Tom|-

-- 
Tom Van Flandern / Washington, DC / metares@well.sf.ca.us
Meta Research was founded to foster research into ideas not otherwise
supported because they conflict with mainstream theories in Astronomy.