Are Black Holes Dark Matter factories?

(Hans Aberg) writes:

In article , Ulf Torkelsson
wrote:

From what one knows about other physics, such an instability seems
unlikely. There ought to be a mechanism that makes the universe to
hang together and adjusts appropriately, even if the masses
varies. That is just a hunch.

We do not observe a static universe, so there is no reason
to expect this kind of fine-tuning.

I am not speaking about a static universe, but one in which the
cosmological constant can adjust.

The problem with what you are speaking about is that it is oxymoronic:
The cosmological constant is, by definition, _CONSTANT_. If the C.C. were
to "adjust" or vary in any way, then the covariant divergence of the
stress-energy-momentum tensor would be non-zero, and matter, energy,
and momentum would be created from nothing; this is Considered Bad.
If the C.C. has =ANY= type of "dynamics" at all, it ceases to be a
"cosmological constant," and becomes just one more "matter" field,
and these days is usually referred to as a "quintessence."


I try to think it in terms of the Lagrangian used to create the
Einstein-Hilbert equation of GR. The scalar curvature and the
energy-momentum pushes it one direction. The cosmological constant is a
component that pushes it the other direction. The EM components can push
it either direction, though.

The last statement is confusing. EM could mean two things here, either
radiation, which has a positive energy density and pressure, and which
therefore contributes to the attractive gravity, or you could think of
electrostatic forces, which will contribute with a repulsive force if there
is a net charge in the universe, but otherwise the effect of the
electrostatic forces will be negligible on the global scale.

The energy density should be what one gets after plugging in an observer
in the stress-energy tensors that result after the metric variation in the
GR Lagrangian.

What do you mean by "plugging an observer into the stress-energy tensors"?
This statement sound suspiciously like "technobabble" to me. For one thing,
please note that it is =THE= stress-energy-momentum tensor: singular, not plural.
For another, one does not "plug an observer into it." One can plug "one-forms"
into it, or vectors if one lowers an index using the metric, but an "observer"
is neither a one-form nor a vector. Please explain what you mean by the above
statement.


-- Gordon D. Pusch

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