Are Black Holes Dark Matter factories?

Has anyone ever seen work on a theory that Black Holes are Dark Matter factories?

Thank you,

Ned

(Ned Flanders) writes:

Has anyone ever seen work on a theory that Black Holes are Dark Matter
factories?

Since by definition, nothing can escape from the interior of a black hole
according to "classical" physics --- not even "dark matter" --- and quantum
mechanically, the rate of Hawking radiation becomes utterly negligible for
macroscopic black holes, there would be very little point to postulating
that black holes are "dark matter factories."

Furthermore, even if there were some mysterious process converting normal
matter to "dark matter" that for some mysterious region only functioned
in the inner regions of a black hole's accretion disk, only a very small
fraction of that nascent "dark matter" could escape the black hole via
its jets; the overwhelming majority of the nascent "dark matter" would
simply be swallowed up by the black hole, like any other form of matter.


-- Gordon D. Pusch

perl -e '$_ = \n"; s/NO\.//; s/SPAM\.//; print;'

(Ned Flanders) writes:

Has anyone ever seen work on a theory that Black Holes are Dark Matter
factories?

Since by definition, nothing can escape from the interior of a black hole
according to "classical" physics --- not even "dark matter" --- and quantum
mechanically, the rate of Hawking radiation becomes utterly negligible for
macroscopic black holes, there would be very little point to postulating
that black holes are "dark matter factories."

Furthermore, even if there were some mysterious process converting normal
matter to "dark matter" that for some mysterious region only functioned
in the inner regions of a black hole's accretion disk, only a very small
fraction of that nascent "dark matter" could escape the black hole via
its jets; the overwhelming majority of the nascent "dark matter" would
simply be swallowed up by the black hole, like any other form of matter.


-- Gordon D. Pusch

perl -e '$_ = \n"; s/NO\.//; s/SPAM\.//; print;'

In article ,
(Gordon D. Pusch) wrote:

Has anyone ever seen work on a theory that Black Holes are Dark Matter
factories?

Since by definition, nothing can escape from the interior of a black hole
according to "classical" physics --- not even "dark matter" --- and quantum
mechanically, the rate of Hawking radiation becomes utterly negligible for
macroscopic black holes, there would be very little point to postulating
that black holes are "dark matter factories."

Furthermore, even if there were some mysterious process converting normal
matter to "dark matter" that for some mysterious region only functioned
in the inner regions of a black hole's accretion disk, only a very small
fraction of that nascent "dark matter" could escape the black hole via
its jets; the overwhelming majority of the nascent "dark matter" would
simply be swallowed up by the black hole, like any other form of matter.

Is the "dark matter" the same thing as the "dark energy" that some
speculate should act as a anti-gravitational ("levity") force? (It seems
me better to let "dark matter" denote matter which is not visible by
self-emitting radiation.)

As for the reasoning above, one should note that the definition of a "
black hole" means that by gravitational forces nothing can escape. The
Hawking radiation rate is indeed very low, but Hawking does not try to
combine the GR and QM to a single theory to see what happens, but merely
assumes that there are particle pairs within and without a sharp classical
GR event horizon. He then notes that some energy can escape, even under
these restricted assumptions.

So nobody knows what happens when GR and QM is combined. There is room for
a combined GRQM theory in which normal matter is tunneling out of the
black hole. Whether such hypothetically tunneling matter will be sucked
back into the black hole again or not will depend on its momentum when
leaving the black hole, gather.

Whether it is meaningful or not to create such theories, I gather, will
ultimately depend on whether there are observational data to compare
against. The best would be if one could measure down what, if anything,
leaves the black holes.

What I heard about "dark energy" was that one experimented with such
theories in order to explain the "acceleration of the universe", that is,
that expansion rates of visible matter are lower further out from us. This
would then be a long range "levity" force. It does then not seem to have
anything to do with the black hole forces, which act on a much shorter
distance.

Hans Aberg

In article ,
(Gordon D. Pusch) wrote:

Has anyone ever seen work on a theory that Black Holes are Dark Matter
factories?

Since by definition, nothing can escape from the interior of a black hole
according to "classical" physics --- not even "dark matter" --- and quantum
mechanically, the rate of Hawking radiation becomes utterly negligible for
macroscopic black holes, there would be very little point to postulating
that black holes are "dark matter factories."

Furthermore, even if there were some mysterious process converting normal
matter to "dark matter" that for some mysterious region only functioned
in the inner regions of a black hole's accretion disk, only a very small
fraction of that nascent "dark matter" could escape the black hole via
its jets; the overwhelming majority of the nascent "dark matter" would
simply be swallowed up by the black hole, like any other form of matter.

Is the "dark matter" the same thing as the "dark energy" that some
speculate should act as a anti-gravitational ("levity") force? (It seems
me better to let "dark matter" denote matter which is not visible by
self-emitting radiation.)

As for the reasoning above, one should note that the definition of a "
black hole" means that by gravitational forces nothing can escape. The
Hawking radiation rate is indeed very low, but Hawking does not try to
combine the GR and QM to a single theory to see what happens, but merely
assumes that there are particle pairs within and without a sharp classical
GR event horizon. He then notes that some energy can escape, even under
these restricted assumptions.

So nobody knows what happens when GR and QM is combined. There is room for
a combined GRQM theory in which normal matter is tunneling out of the
black hole. Whether such hypothetically tunneling matter will be sucked
back into the black hole again or not will depend on its momentum when
leaving the black hole, gather.

Whether it is meaningful or not to create such theories, I gather, will
ultimately depend on whether there are observational data to compare
against. The best would be if one could measure down what, if anything,
leaves the black holes.

What I heard about "dark energy" was that one experimented with such
theories in order to explain the "acceleration of the universe", that is,
that expansion rates of visible matter are lower further out from us. This
would then be a long range "levity" force. It does then not seem to have
anything to do with the black hole forces, which act on a much shorter
distance.

Hans Aberg

In article ,
(Hans Aberg) writes:

Is the "dark matter" the same thing as the "dark energy" that some
speculate should act as a anti-gravitational ("levity") force? (It seems
me better to let "dark matter" denote matter which is not visible by
self-emitting radiation.)

"Dark energy" is a newfangled name for the cosmological constant. As
Sean Carroll points out, a better name would be "smooth tension". The
reasoning goes something like this: lots of things are dark, and
everything has energy. The interesting thing about the cosmological
constant is that it is negative pressure, otherwise known as tension.
Also, it is not concentrated in objects, but rather homogeneously
distributed. Hence, smooth tension.

I hereby claim the right to "Smooth Tension" as the name for a
progressive-rock group, if I ever get around to founding one. I can see
it written on both bass drums now. :-) (Which reminds me, I believe
that guitarist Brian May of Queen was once a student of astronomy but
gave it up when he started making money with Queen. Anyone who knows
details can provide them to me via email.)

In article ,
(Hans Aberg) writes:

Is the "dark matter" the same thing as the "dark energy" that some
speculate should act as a anti-gravitational ("levity") force? (It seems
me better to let "dark matter" denote matter which is not visible by
self-emitting radiation.)

"Dark energy" is a newfangled name for the cosmological constant. As
Sean Carroll points out, a better name would be "smooth tension". The
reasoning goes something like this: lots of things are dark, and
everything has energy. The interesting thing about the cosmological
constant is that it is negative pressure, otherwise known as tension.
Also, it is not concentrated in objects, but rather homogeneously
distributed. Hence, smooth tension.

I hereby claim the right to "Smooth Tension" as the name for a
progressive-rock group, if I ever get around to founding one. I can see
it written on both bass drums now. :-) (Which reminds me, I believe
that guitarist Brian May of Queen was once a student of astronomy but
gave it up when he started making money with Queen. Anyone who knows
details can provide them to me via email.)

In article , Ulf Torkelsson
wrote:

This even distribution, not attached to objects, is also what causes
problems with the cosmological constant, producing unstable universes.

I cannot see that this is a problem, since we observe the universe to be
expanding just like we expect from the Friedman-Robertson-Walker model.

This refers to the problems, which I recall you mentioned before, that a
non-zero cosmological constant causes exponential growth in the universe
if it is not exactly right. I do not recall the details.

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.

Therefore, I think one may experiment with a "cosmological variable",
which varies over space, perhaps acting on a longer distance and attached
to certain classes of objects (such as visible matter).

The idea pleases me, because in the QM microcosm, there is a strong force
with the capacity to counteract the EM forces in the atomic nuclei. The
electrostatic force is distance proportional to 1/r, same as gravity.

The 1/r law applies to the potentials, not the forces that go as 1/r^2

Right. Sorry for the confusion.

Then, if one adds an anti-gravitational "levity" force to GR, that makes
the new theory look more like some kind of dual to QM. Its distance
formula should be so that in short distances it is negligible relative
gravity, but in long distances, it should be able to counteract the GR
GM/(c^2 r) asymptotic formula that Ulf Torkelsson before described here.

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.

I got the Lagrangian to
L := s_g + g(F, F) + sum_j(g(P_j, P_j) + m_j^2 + e_j g(P_j, A))
where s_g is the scalar curvature, F the EM two-form, A the EM potential,
and P_j the energy-momentum and e_j the electric charge of the particles.

It is better to note that
in general
relativity the source of the gravitational field is rho + 3p, where rho
is the
energy density and p is the pressure. Now, quintessence can be thought of
as a field with p = w rho, where -1/3 w = -1. The equality is true if we
have a pure vacuum energy, that is a cosmological constant. Since rho must
be positive, we see that the gravitational field reverses its sign and
becomes
repulsive if it is dominated by quintessence.

(Sorry for my poor memory; I do not have reference books where I sit.) The
Einstein-Hilbert cosmological constant I recall to be something that is
added to the equation that results after the metric variation. Then I do
not immediately see what it should looks like before the metric variation.
Perhaps you can help out here?

Hans Aberg

In article , Ulf Torkelsson
wrote:

This even distribution, not attached to objects, is also what causes
problems with the cosmological constant, producing unstable universes.

I cannot see that this is a problem, since we observe the universe to be
expanding just like we expect from the Friedman-Robertson-Walker model.

This refers to the problems, which I recall you mentioned before, that a
non-zero cosmological constant causes exponential growth in the universe
if it is not exactly right. I do not recall the details.

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.

Therefore, I think one may experiment with a "cosmological variable",
which varies over space, perhaps acting on a longer distance and attached
to certain classes of objects (such as visible matter).

The idea pleases me, because in the QM microcosm, there is a strong force
with the capacity to counteract the EM forces in the atomic nuclei. The
electrostatic force is distance proportional to 1/r, same as gravity.

The 1/r law applies to the potentials, not the forces that go as 1/r^2

Right. Sorry for the confusion.

Then, if one adds an anti-gravitational "levity" force to GR, that makes
the new theory look more like some kind of dual to QM. Its distance
formula should be so that in short distances it is negligible relative
gravity, but in long distances, it should be able to counteract the GR
GM/(c^2 r) asymptotic formula that Ulf Torkelsson before described here.

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.

I got the Lagrangian to
L := s_g + g(F, F) + sum_j(g(P_j, P_j) + m_j^2 + e_j g(P_j, A))
where s_g is the scalar curvature, F the EM two-form, A the EM potential,
and P_j the energy-momentum and e_j the electric charge of the particles.

It is better to note that
in general
relativity the source of the gravitational field is rho + 3p, where rho
is the
energy density and p is the pressure. Now, quintessence can be thought of
as a field with p = w rho, where -1/3 w = -1. The equality is true if we
have a pure vacuum energy, that is a cosmological constant. Since rho must
be positive, we see that the gravitational field reverses its sign and
becomes
repulsive if it is dominated by quintessence.

(Sorry for my poor memory; I do not have reference books where I sit.) The
Einstein-Hilbert cosmological constant I recall to be something that is
added to the equation that results after the metric variation. Then I do
not immediately see what it should looks like before the metric variation.
Perhaps you can help out here?

Hans Aberg

In article ,
Phillip Helbig---remove CLOTHES to reply wrote:
[...]
"Dark energy" is a newfangled name for the cosmological constant. As
Sean Carroll points out, a better name would be "smooth tension".

Ooh, nice name.

I hereby claim the right to "Smooth Tension" as the name for a
progressive-rock group, if I ever get around to founding one. I can see
it written on both bass drums now. :-) (Which reminds me, I believe
that guitarist Brian May of Queen was once a student of astronomy but
gave it up when he started making money with Queen. Anyone who knows
details can provide them to me via email.)

A friend was setting up a violin, etc. performing group and
asked around for suggestions of names ("string beings" was my
favorite among her candidates, though she somehow didn't like
that one). I suggested "Robin K. and her 11-dimensional strings".
She didn't go with it, but I still hope someone to see someone
use a name like that someday.

[Mod. note: OK, I feel further discussion along these lines would be
best in some other newsgroup, though I have to say I'm not sure what
-- mjh]