In article ,
(Phillip Helbig---remove CLOTHES to reply)
wrote:

Sadly, as others have already observed, a "cosmological constant" does
=NOT= lead to a "stable" universe, convecting or otherwise; it leads to
an UNSTABLE universe that undergoes either runaway expansion or collapse.
It is analogous to trying to balance a pencil on its point: The Universe
"wants" to fall over into either an implosion or explosion.

That's true. The same argument can be used against the Einstein-de
Sitter universe. Why it wasn't (until the discussion of the "flatness
problem" turned up a couple of decades ago) is an interesting historical
question. Of course, there are other arguments against the static
universe (such as the fact that the universe is expanding), but that
only strengthens the disbelief in this model, not the credibility of
other arguments against it.

An idea that comes to my mind, by considering the generalized GR
Einstein-Hilbert equation that I discussed in earlier postings of this
thread, is that the universe might achieve its stability by a balance
between visible and dark matter: Suppose (as a thought experiment, even
though it may sound strange) that the visible matter has a special levity
force, perhaps due to its QM activities, which then would generate a
pressure on the before mentioned Lagrangian in a direction opposite to
that of classical matter. Then this would put a pressure on visible matter
to move apart, which dark matter would instead contract, until it ignites.
If there is an instability, the universe would adjust by producing more of
dark/visible matter, whatever needed to achieve the stability again.

There are several problems with such a model: Why isn't there a pressure
making double stars falling apart (perhaps the levity force only acts on
longer distances). And why isn't the universe more homogenous with respect
to local age differences of galaxies, i.e., why aren't there say more
quasars local to us. In general, the more homogeneous the universe (or our
"glob") is with respect to such local age differences of galaxies, the
older it should be.

I should also have said that the original reason that I started to think
about "cosmic convection" is if it possible for black hole matter to
tunnel out of the black hole. This might be possible via a generalized GR
Einstein-Hilbert equation as above, because then particles near the black
hole classical event horizon will have a state simultaneously inside and
outside it: The GRQM event horizon will be "fuzzy", not sharp. One can
construct intrinsic particle spin by letting the Clifford bundle acting on
the differential forms algebra. Then the Levi-Civita connection, which
communicates gravity in GR, will act trivially on those differential
forms. This suggests that at least intrinsic particle spin will be
preserved when matter entering a black hole, and therefore also if
tunneling out of it, if that is possible.

If this process generalizes so that other fundamental particle invariants
are preserved when entering the black hole (which should be in the case of
the GRQM Fock space model I mentioned, as it is known, I think, that the
Levi-Civita connection will be trivial on the cotensor bundle part), then
the particles tunneling out of the black hole might be the stable
particles composed of those invariants. This matter might then be not so
energetic, explaining why it can't be observed as visible matter.

And then one gets, at least locally, also dark matter leaving the
galaxies, i.e., from the black hole at the hub. This should be in the form
of a weak particle stream sort of trickling out of it.

Hans Aberg