Dark Matter Paradox / Black Hole Runaway

OK, I'll pose a problem. Time for an Original Post from me ;-)

If, as conjectured, dark matter pervades the Universe, (making up as
much as 24% of the mass in the universe) why hasn't/isn't any of this
been swallowed into the ultimate gravitational attractor. Why are there
so few black holes around and why are they so small if we are awash in
"Darth Matter"? Why are they the result only of stellar collapse? Why
don't they just form spontaneously out of the Dark Matter aether?

David

"David Spain" wrote in message
m...

OK, I'll pose a problem. Time for an Original Post from me ;-)

If, as conjectured, dark matter pervades the Universe, (making up as much
as 24% of the mass in the universe) why hasn't/isn't any of this been
swallowed into the ultimate gravitational attractor. Why are there so few
black holes around and why are they so small if we are awash in "Darth
Matter"? Why are they the result only of stellar collapse? Why don't they
just form spontaneously out of the Dark Matter aether?

I'd say because they've never achieved the density required. Even the early
lumpiness of the Universe probably didn't provide enough density for dark
matter objects to form. If they can't form, no "dark matter stars" no black
holes.

As for few black holes, not so much. I believe they pretty much believe
every galaxy as a decent sized one in the center.



David



--
Greg D. Moore http://greenmountainsoftware.wordpress.com/
CEO QuiCR: Quick, Crowdsourced Responses. http://www.quicr.net

On 2/14/2013 11:06 AM, Greg (Strider) Moore wrote:

"David Spain" wrote in message
...

OK, I'll pose a problem. Time for an Original Post from me ;-)

If, as conjectured, dark matter pervades the Universe, (making up as
much as 24% of the mass in the universe) why hasn't/isn't any of this
been swallowed into the ultimate gravitational attractor. Why are
there so few black holes around and why are they so small if we are
awash in "Darth Matter"? Why are they the result only of stellar
collapse? Why don't they just form spontaneously out of the Dark
Matter aether?

I'd say because they've never achieved the density required. Even the
early lumpiness of the Universe probably didn't provide enough density
for dark matter objects to form. If they can't form, no "dark matter
stars" no black holes.

As for few black holes, not so much. I believe they pretty much believe
every galaxy as a decent sized one in the center.


OK that could explain why we don't see spontaneously forming black holes
out of nothing...

But if I give the existing ones 24% more mass than was previously
considered available why are they size we see? Why are their event
horizon diameters pretty much in line with theory that says its due to
mass obtained from 'non-dark'?

I call this the 'Miami-Beach Theory'. A black hole may have no hair, but
as far as dark matter is concerned it must also be wearing sunglasses,
and if its name happens to be Kerr, a significant equatorial bulge. In
other words a fat, balding 'hole', hanging around the beach with Tequila
in hand, with sunglasses on to filter out all the WIMPs leaving them
only the ability to see the bikini clad "Material Girls"...

Dave

Maybe they cannot collide and hence cannot form into huge masses. However,
if that was the case, then what bends the light near where it is said a lot
of it exists?

Brian

--
From the Bed of Brian Gaff.
The email is valid as
Blind user.
"David Spain" wrote in message
...
OK, I'll pose a problem. Time for an Original Post from me ;-)

If, as conjectured, dark matter pervades the Universe, (making up as much
as 24% of the mass in the universe) why hasn't/isn't any of this been
swallowed into the ultimate gravitational attractor. Why are there so few
black holes around and why are they so small if we are awash in "Darth
Matter"? Why are they the result only of stellar collapse? Why don't they
just form spontaneously out of the Dark Matter aether?

David

The imbalance between the matter and anti matter is also a bit puzzling
could the imbalance of gravity and apparent mass with nothing solid to
create it be part of the result of the imbalance. Gravity seems to be a
force which only has one pole. You do not get anti gravity do you.
Brian

--
From the Bed of Brian Gaff.
The email is valid as
Blind user.
"Greg (Strider) Moore" wrote in message
m...

"David Spain" wrote in message
om...

OK, I'll pose a problem. Time for an Original Post from me ;-)

If, as conjectured, dark matter pervades the Universe, (making up as much
as 24% of the mass in the universe) why hasn't/isn't any of this been
swallowed into the ultimate gravitational attractor. Why are there so few
black holes around and why are they so small if we are awash in "Darth
Matter"? Why are they the result only of stellar collapse? Why don't they
just form spontaneously out of the Dark Matter aether?

I'd say because they've never achieved the density required. Even the
early lumpiness of the Universe probably didn't provide enough density for
dark matter objects to form. If they can't form, no "dark matter stars"
no black holes.

As for few black holes, not so much. I believe they pretty much believe
every galaxy as a decent sized one in the center.



David



--
Greg D. Moore
http://greenmountainsoftware.wordpress.com/
CEO QuiCR: Quick, Crowdsourced Responses. http://www.quicr.net

On Wednesday, February 13, 2013 7:23:32 PM UTC-5, David Spain wrote:
OK, I'll pose a problem. Time for an Original Post from me ;-)



If, as conjectured, dark matter pervades the Universe, (making up as

much as 24% of the mass in the universe) why hasn't/isn't any of this

been swallowed into the ultimate gravitational attractor. Why are there


so few black holes around and why are they so small if we are awash in

"Darth Matter"? Why are they the result only of stellar collapse? Why

don't they just form spontaneously out of the Dark Matter aether?



David

I am no expert but this is my understanding of the current theory.

When regular matter collides part of the kinetic energy in the collision is
radiated away as heat (EM radiation) which causes matter to lump together
relatively easily. This is due to electromagnetic interactions. Regular mat
ter also has other interactions, like the nuclear forces.

Unlike regular matter, dark matter is believed to only interact gravitation
ally, with itself and also with regular matter; there are no other known in
teractions. This means that when two "clouds" of dark matter collide they j
ust pass right through each other without any loss of kinetic energy. They
may later slow down by gravitational attraction and change direction for an
other pass-through. Since there is no mechanism by which kinetic energy can
be lost this cycle could go on forever (almost), like an ideal oscillator.
This is what prevents dark matter from lumping together. Same happens when
dark matter collides with regular matter.

Now, since it interacts gravitationally, dark matter should obey General Re
lativity, in that it should radiate energy as gravitational waves, and give
n a sufficiently long time should slow down and eventually lump together. I
can’t give you an estimate for how long that would take, maybe much long
er than the age of the Universe.

Regarding black holes, I would assume that dark matter falling in should st
ay in and add to the mass of the BH, just like regular matter. I don’t th
ink there’s a way to tell what proportion of a BH’s mass comes from reg
ular or dark matter. But, per above, I don’t think dark matter itself cou
ld form a BH that wasn’t there in the first place, unless given a very ve
ry long time.

As people have said before though, there are problems even obn the level you
state. What started the motion of dark matter in the first place and how can
it clump if its so very low in interactablity?

I'm loathe to mention it, but since the speed of light appears to be the
same in any local frame of reference we can devise, how can anyone tell what
is moving in relation to what. there is no centre of the universe, just a
horison we cannot see beyond. Thus when talking about that other
inconvenient p issue, dark energy, nobody can say there is not a huge
enclosure to the universe that as it balloons out does not drag the space
within it with it stretching it out. All we see is red shift surely?

Brian

--
From the Bed of Brian Gaff.
The email is valid as
Blind user.
wrote in message
...
On Wednesday, February 13, 2013 7:23:32 PM UTC-5, David Spain wrote:
OK, I'll pose a problem. Time for an Original Post from me ;-)



If, as conjectured, dark matter pervades the Universe, (making up as

much as 24% of the mass in the universe) why hasn't/isn't any of this

been swallowed into the ultimate gravitational attractor. Why are there


so few black holes around and why are they so small if we are awash in

"Darth Matter"? Why are they the result only of stellar collapse? Why

don't they just form spontaneously out of the Dark Matter aether?



David

I am no expert but this is my understanding of the current theory.

When regular matter collides part of the kinetic energy in the collision is
radiated away as heat (EM radiation) which causes matter to lump together
relatively easily. This is due to electromagnetic interactions. Regular mat
ter also has other interactions, like the nuclear forces.

Unlike regular matter, dark matter is believed to only interact gravitation
ally, with itself and also with regular matter; there are no other known in
teractions. This means that when two "clouds" of dark matter collide they j
ust pass right through each other without any loss of kinetic energy. They
may later slow down by gravitational attraction and change direction for an
other pass-through. Since there is no mechanism by which kinetic energy can
be lost this cycle could go on forever (almost), like an ideal oscillator.
This is what prevents dark matter from lumping together. Same happens when
dark matter collides with regular matter.

Now, since it interacts gravitationally, dark matter should obey General Re
lativity, in that it should radiate energy as gravitational waves, and give
n a sufficiently long time should slow down and eventually lump together. I
can’t give you an estimate for how long that would take, maybe much long
er than the age of the Universe.

Regarding black holes, I would assume that dark matter falling in should st
ay in and add to the mass of the BH, just like regular matter. I don’t th
ink there’s a way to tell what proportion of a BH’s mass comes from reg
ular or dark matter. But, per above, I don’t think dark matter itself cou
ld form a BH that wasn’t there in the first place, unless given a very ve
ry long time.

Poster ' gave basically the right answer.

In article ,
"Brian Gaff" writes:
What started the motion of dark matter in the first place

Gravity.

and how can it clump if its so very low in interactablity?

Gravity. Look at a globular cluster for example. The stars don't
collide or dissipate energy, but the cluster stays bound. I'm
oversimplifying a bit, but analysis show the dark matter clumpiness
grows over time, and simulations show the same thing. There's a nice
movie at
http://www.mpa-garching.mpg.de/galform/millennium/
though I fear it won't do much good if you are blind. Basically it
shows all the (simulated) dark matter particles zooming around, but
they tend to concentrate in overdense regions, and the size of the
overdense structures grows with time.

I'm loathe to mention it, but since the speed of light appears to be the
same in any local frame of reference we can devise, how can anyone tell what
is moving in relation to what.

It's easy to measure relative motion. There is, so far as we know,
no absolute rest frame.

there is no centre of the universe, just a horison we cannot see
beyond.

Right, or at least so we think now.

I'm afraid I don't understand the rest of the post, but something
outside our horizon shouldn't have any effect on what we observe
unless that something was previously in causal contact. Dark energy
remains mysterious, but a cosmological constant is certainly one
candidate for what it might be.

--
Help keep our newsgroup healthy; please don't feed the trolls.
Steve Willner Phone 617-495-7123
Cambridge, MA 02138 USA

Steve,

I'm not sure I'm buying the 'low density' argument in the vicinity of a
black hole. If a BH can form an accretion disk of ordinary matter why is
dark matter so selectively able to 'stay away'?

Well the day job is getting in the way of doing more research on this
topic today. I'll try to follow up with a better reasoned argument when
I can find the time to do so.

Dave

On 3/5/2013 12:10 PM, wrote:
Regarding black holes, I would assume that dark matter falling in should st
ay in and add to the mass of the BH, just like regular matter.

I would too.

I don’t think there’s a way to tell what proportion of a BH’s mass comes from reg
ular or dark matter. But, per above, I don’t think dark matter itself could form
a BH that wasn’t there in the first place, unless given a very very
long time.

Well maybe, you have to define 'long time'. Esp. since we know the
Cosmic Microwave Background is not uniform, why do we think gravitation
should be?

However, my main issue is how does DM respond in the vicinity of a BH?
If it's really there, Swartzchild's calculations would have or should
have been way off.

Maybe they are. I don't know how much experimental/observational rigor
has been applied in trying to determine the theories accuracy. More
research I need to do that I don't have the time for right now.

Those who have knowledge in this area are always welcome to contribute
what they know! Steve?


Dave