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- Newsgroups: sci.astro
- Path: sparky!uunet!well!metares
- From: metares@well.sf.ca.us (Tom Van Flandern)
- Subject: Re: "Modeling" the Expanding Universe?
- Message-ID: <C1KnCo.5rH@well.sf.ca.us>
- Sender: news@well.sf.ca.us
- Organization: Whole Earth 'Lectronic Link
- References: <Jan.25.00.49.10.1993.28941@ruhets.rutgers.edu> <1k01r5INNr52@gap.caltech.edu> <schumach.727998698@convex.convex.com>
- Date: Thu, 28 Jan 1993 16:05:11 GMT
- Lines: 68
-
-
- 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.
-