Black Holes and quasars

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Message 248111 - Posted: 14 Feb 2006, 20:30:38 UTC

If light can not escape a black hole why can noise? Is there something going on here that takes place at a high energy to overcome the physics of the four forces?

So a quasar is a collapsed galaxy? What happed to the all the black holes?

Forgive me if these are amiture astronomy questions. I have never been clear on these questions, but I would like to lear more.
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Message 248219 - Posted: 14 Feb 2006, 23:03:19 UTC
Last modified: 14 Feb 2006, 23:04:29 UTC

LoL. I like you questions about the quasar.
Disclaimer: I don't believe in black holes.

Anyway, sound as we know it is from changing pressures in gas/matter. Gas being consumed by a black hole would be, by default, changing the pressure or density of the gas/matter. This pressure change would propagate outward. Thus, sound could escape a black hole in a sense, but it's only causing density change in matter.

I don't think quasars are necessarily collapsed galaxies, but I don't really have any speculations on that. I do think people beleive that they are powered by a black hole.

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Message 248322 - Posted: 15 Feb 2006, 2:37:24 UTC - in response to Message 248111.  
Last modified: 15 Feb 2006, 3:08:18 UTC


If light can not escape a black hole why can noise? Is there something going on here that takes place at a high energy to overcome the physics of the four forces?


Nothing can escape a black hole once its past the event horizon, the radius at which the escape velocity is equal to the speed of light. Outside of that, light and extremely fast matter can and does escape. That extremely fast matter is what you're actually seeing when you see a quasar.

[edit]
I think you may be confusing "sound" with the radio waves that are emittied from Quasi Stellar Radio Sources (quasars). While Sleestak is correct in saying sound is nothing more than the propagation of density waves, I'm not aware of any observations of such a thing around black holes. Radio waves are just another wavelength of light that we happen to use to encode signals for your radio; they are not sound waves.
[/edit]

A black hole is simply the extreme case of physics. Its existence does not overcome the physics of the four forces; it is a direct consequence of the interplay between them. Black holes occur when there is so much mass that force of gravity becomes stronger than the other three fundamental forces. This is possible because gravity, unlike the other forces, is only an attractive force and it can act over an infinite range.


So a quasar is a collapsed galaxy? What happed to the all the black holes?


A quasar is a baby galaxy, the first stage in its evolution. We know this because when we scan the sky, we only see them at high redshift, which means they're very far away and when they emitted their light, the universe was just a fraction of its current age. As we look at various red shifts (various epochs of the universe), we can see a gradual decline of quasars and a gradual increase of galaxies.

Black holes are still at the center of most galaxies, but since they've run out of matter to accrete, you don't see them. There's a common misconception that black holes suck in everything. This is not the case. If the sun were replaced by a black hole of equal mass, the orbits of the planets wouldn't change at all.

Black holes can "evaporate," which is a consequence of the uncertainty principle and vacuum energy, but the timescales on which they do so are much greater than the current age of the universe.

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Try the Wiki for other questions.
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Message 248553 - Posted: 15 Feb 2006, 17:41:25 UTC - in response to Message 248219.  
Last modified: 15 Feb 2006, 17:45:18 UTC


....Disclaimer: I don't believe in black holes....


Might it have anything to do with George Chapline's theory, Dark Energy Stars? Dark Energy Stars abstract

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Message 248594 - Posted: 15 Feb 2006, 19:06:20 UTC - in response to Message 248553.  


....Disclaimer: I don't believe in black holes....


Might it have anything to do with George Chapline's theory, Dark Energy Stars? Dark Energy Stars abstract


LOL, do you realize that I linked that paper a while back? And no, I independently agree with their conclusions for separate reasons.

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Message 248623 - Posted: 15 Feb 2006, 20:08:37 UTC
Last modified: 15 Feb 2006, 20:09:14 UTC

I believe in black holes. Even after reading the pdf there is not enough data to convince me that the SG-1 has it all wrong.



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Message 248664 - Posted: 15 Feb 2006, 21:17:51 UTC - in response to Message 248623.  

I believe in black holes. Even after reading the pdf there is not enough data to convince me that the SG-1 has it all wrong.



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What data convinces you that there are black holes?

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Message 248725 - Posted: 16 Feb 2006, 0:03:28 UTC

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Message 248743 - Posted: 16 Feb 2006, 1:04:59 UTC - in response to Message 248594.  
Last modified: 16 Feb 2006, 1:09:01 UTC


....Disclaimer: I don't believe in black holes....


Might it have anything to do with George Chapline's theory, Dark Energy Stars? Dark Energy Stars abstract


LOL, do you realize that I linked that paper a while back? And no, I independently agree with their conclusions for separate reasons.


I did happen to catch a post awhile back about Chaplines theory but couldn't find it again. I thought that it might of been you that posted it but wasn't sure. Yeah I found it here.

I've had Chaplines Dark Energy Stars on .pdf for a long time on my computer, and another person posted the story here at the science board many months ago. Maybe Thierry Van Driessche could help find the first post again.

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Message 248789 - Posted: 16 Feb 2006, 2:53:34 UTC - in response to Message 248743.  

HEHE, that links to the link where I first posted it on the Black holes 'do not exist' thread. :) I'm not trying to start any arguments.

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Message 248834 - Posted: 16 Feb 2006, 5:34:24 UTC - in response to Message 248789.  

HEHE, that links to the link where I first posted it on the Black holes 'do not exist' thread. :) I'm not trying to start any arguments.


Yes, THNX for your clarification. It's just that the link I provided was easier to find. Simply, I was just wondering if the Chapline idea might be one reason for you not believing in black holes. In the Black holes 'do not exist' thread, your introductory post referrences the Dark Energy Stars paper.

Having read that thread more thoroughly today, I don't think that there's that much more I could add to the thread's specific subject, since Solomon already did a good job in his explanations. :)







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Message 248928 - Posted: 16 Feb 2006, 13:40:21 UTC

Although, I think that Solomon and Jason made some intersting points about the how blackholes behave, I feel the explanation broke down at the singularity and what happens to the energy of the mass.

Anyhow, the question I currently have on my mind is:

If "dark matter" makes up 73% of the universe, why is it mysteriously absent from our solar system and anywhere near us? 73% is a big claim and with that much one would expect to see a few % here or at least somewhere near us. It should have effected our physics.

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Message 249000 - Posted: 16 Feb 2006, 17:01:48 UTC - in response to Message 248928.  

Although, I think that Solomon and Jason made some intersting points about the how blackholes behave, I feel the explanation broke down at the singularity and what happens to the energy of the mass.

Anyhow, the question I currently have on my mind is:

If "dark matter" makes up 73% of the universe, why is it mysteriously absent from our solar system and anywhere near us? 73% is a big claim and with that much one would expect to see a few % here or at least somewhere near us. It should have effected our physics.


What makes you think it is absent? If (as is generally believed among people who study the subject) dark matter is particles which interact through nothing other than gravity and, possibly, the weak force, it would need to be present in very large quantities to be detectible through either of these interactions. Remember that our solar system, or even the disk of our galaxy, is orders of magnitude denser in baryonic (ordinary) matter than the universe as a whole.
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Message 249020 - Posted: 16 Feb 2006, 21:15:07 UTC - in response to Message 249000.  
Last modified: 16 Feb 2006, 21:15:38 UTC



What makes you think it is absent? If (as is generally believed among people who study the subject) dark matter is particles which interact through nothing other than gravity and, possibly, the weak force, it would need to be present in very large quantities to be detectible through either of these interactions. Remember that our solar system, or even the disk of our galaxy, is orders of magnitude denser in baryonic (ordinary) matter than the universe as a whole.



73% is a large quantity, and if it only interacts with gravity and possibly the weak force, then there should be a significant concentration with the sun since it would not be evenly distrubed due to the supposed gravitational interactions. This would result in the sun being appoximately 3-4 times more massive than it is as a result from dark matter.

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Message 249150 - Posted: 17 Feb 2006, 0:25:01 UTC - in response to Message 248928.  
Last modified: 17 Feb 2006, 0:39:38 UTC

Although, I think that Solomon and Jason made some intersting points about the how blackholes behave, I feel the explanation broke down at the singularity and what happens to the energy of the mass.

Anyhow, the question I currently have on my mind is:

If "dark matter" makes up 73% of the universe, why is it mysteriously absent from our solar system and anywhere near us? 73% is a big claim and with that much one would expect to see a few % here or at least somewhere near us. It should have effected our physics.


On the absence of dark matter in our solar system or anywhere near us question: I'd say that it's mysteriously absent because perhaps it does not exist. Indeed 73 percent IS a big claim, but that percentage also includes dark energy. 73% is supposedly dark energy, while about 23% is dark matter. Yes, that would mean that only about 4% of the known universe would be of ordinary matter. The mainstream dark matter/dark energy theories that explain cosmic acceleration use a field that heavily relies on a certain dubious spin 0 particle that has yet to be discovered, and whose predicted mass has been often changed.

I'm not quite sure about the whole dark matter thing honestly. There's a lot of conflicting information on the subject and it can be confusing sometimes. Here's a link to some conflicting dark matter theories at arxiv that might give you an idea of why I have doubts about it: arxiv

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Message 249152 - Posted: 17 Feb 2006, 0:28:22 UTC - in response to Message 248928.  

Although, I think that Solomon and Jason made some intersting points about the how blackholes behave, I feel the explanation broke down at the singularity and what happens to the energy of the mass.

Anyhow, the question I currently have on my mind is:

If "dark matter" makes up 73% of the universe, why is it mysteriously absent from our solar system and anywhere near us? 73% is a big claim and with that much one would expect to see a few % here or at least somewhere near us. It should have effected our physics.

I am of the belief that dark matter and dark energy are the modern version of ether and epicycles. If someone gets quantum physics and general relativity to gel, the till-then-presumed-to-be-infinitesmal errors introduced by quantum physics' assumption of flat space may account for all of the dark stuff. On the other hand, a currently-unknown mechanism for distorting spaetime that doesn't involve mass or momentum seems more likely to me. For example, maybe huge "creases" were left in spacetime by the aftermath of the Big Bang singularity. Another possibility would be tidal effects magnifying distant gravitational sources due to the large-scale structure of the Universe (Often described as "foam-like." The bubbles on the inside of foam have planar sides instead of the predicted spherical sides because of the interaction with neighboring bubbles.)
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Message 249299 - Posted: 17 Feb 2006, 6:26:03 UTC - in response to Message 249020.  



What makes you think it is absent? If (as is generally believed among people who study the subject) dark matter is particles which interact through nothing other than gravity and, possibly, the weak force, it would need to be present in very large quantities to be detectible through either of these interactions. Remember that our solar system, or even the disk of our galaxy, is orders of magnitude denser in baryonic (ordinary) matter than the universe as a whole.



73% is a large quantity, and if it only interacts with gravity and possibly the weak force, then there should be a significant concentration with the sun since it would not be evenly distrubed due to the supposed gravitational interactions. This would result in the sun being appoximately 3-4 times more massive than it is as a result from dark matter.


73% certainly is a large quantity. And dark matter is certainly not distributed uniformly. However, its distribution is more uniform than that of baryonic matter, and for good reason. Imagine that we have a particle of some kind in orbit about a large mass. The size and shape of its orbit depend on its mechanical energy and its orbital angular momentum. If we wanted to move that particle into a smaller orbit (one where it stays closer to the massive body), it would have to lose energy and possibly angular momentum.

For a particle of baryonic matter, this is not a problem. It can transfer energy and angular momentum to other particles through electromagnetic interactions. In fact, this is a large part of the theory behind the formation of galaxies or stars. Large groupings of matter need to fall together, and to do this they ultimately have to at least shed energy.

For dark matter, on the other hand, interactions are rare and weak, so moving to tigher orbits is not common. The upshot here is that when dark matter is gravitationally bound in a system that also has baryonic matter, the dark matter tends to exist as a halo much larger than any baryonic structure. Consider, for example, our galaxy. The almost all of the baryonic mass of the Milky Way is in the galaxy's disk, which is ~15 kpc in radius and ~1 kpc thick. The dark matter is in roughly spherical halo or radius ~100 kpc. These numbers suggest that the average concentration of baryonic matter in the disk should be three orders of magnitude larger than the average concentration of dark matter in the same area.
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Message 249300 - Posted: 17 Feb 2006, 6:34:20 UTC - in response to Message 249150.  

Although, I think that Solomon and Jason made some intersting points about the how blackholes behave, I feel the explanation broke down at the singularity and what happens to the energy of the mass.

Anyhow, the question I currently have on my mind is:

If "dark matter" makes up 73% of the universe, why is it mysteriously absent from our solar system and anywhere near us? 73% is a big claim and with that much one would expect to see a few % here or at least somewhere near us. It should have effected our physics.


On the absence of dark matter in our solar system or anywhere near us question: I'd say that it's mysteriously absent because perhaps it does not exist. Indeed 73 percent IS a big claim, but that percentage also includes dark energy. 73% is supposedly dark energy, while about 23% is dark matter. Yes, that would mean that only about 4% of the known universe would be of ordinary matter. The mainstream dark matter/dark energy theories that explain cosmic acceleration use a field that heavily relies on a certain dubious spin 0 particle that has yet to be discovered, and whose predicted mass has been often changed.

I'm not quite sure about the whole dark matter thing honestly. There's a lot of conflicting information on the subject and it can be confusing sometimes. Here's a link to some conflicting dark matter theories at arxiv that might give you an idea of why I have doubts about it: arxiv


What you're noticing on the arXiv are the vast range of theoretical contortions people are taking themselves through to try to explain what dark matter could be - and there certainly are a lot of them. I've heard suggestions regarding Supersymmetry, String Theory, and I even went to a talk last week about how dark matter could arise from particles capable of travelling in a fifth, compact dimension.

Clearly, theory has really no idea what the stuff is. But, that doesn't change the observations (and there are many) which demand the presence of unseen, weakly interacting mass.

It's worth noting that we can figure out quite a bit without having to have a theory which predicts the presence of dark mass. If we assume the presence of particles that only interact in the weak ways I've described, we can actually do a very good job of modelling what we would expect to see; and it matches what we do see.
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Message 249306 - Posted: 17 Feb 2006, 7:42:02 UTC - in response to Message 249299.  
Last modified: 17 Feb 2006, 7:42:42 UTC


For dark matter, on the other hand, interactions are rare and weak, so moving to tigher orbits is not common. The upshot here is that when dark matter is gravitationally bound in a system that also has baryonic matter, the dark matter tends to exist as a halo much larger than any baryonic structure. Consider, for example, our galaxy. The almost all of the baryonic mass of the Milky Way is in the galaxy's disk, which is ~15 kpc in radius and ~1 kpc thick. The dark matter is in roughly spherical halo or radius ~100 kpc. These numbers suggest that the average concentration of baryonic matter in the disk should be three orders of magnitude larger than the average concentration of dark matter in the same area.


The closest star is not much more than 1 pc away. The 1/3 of the thickness of 15 kpc alone of would put it well past 30 of the closest stars to us. We can't be sharing our own 73% with other stars for the numbers to count. The stacking would have to be precise for this to work if someone could actually come up with a pattern to deal with the huge numbers of 1 system and the inter mixing would be ridiculous. When you say 100 kpc, that just throws it out of the ballpark.

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Message 249387 - Posted: 17 Feb 2006, 16:11:23 UTC - in response to Message 249306.  


For dark matter, on the other hand, interactions are rare and weak, so moving to tigher orbits is not common. The upshot here is that when dark matter is gravitationally bound in a system that also has baryonic matter, the dark matter tends to exist as a halo much larger than any baryonic structure. Consider, for example, our galaxy. The almost all of the baryonic mass of the Milky Way is in the galaxy's disk, which is ~15 kpc in radius and ~1 kpc thick. The dark matter is in roughly spherical halo or radius ~100 kpc. These numbers suggest that the average concentration of baryonic matter in the disk should be three orders of magnitude larger than the average concentration of dark matter in the same area.


The closest star is not much more than 1 pc away. The 1/3 of the thickness of 15 kpc alone of would put it well past 30 of the closest stars to us. We can't be sharing our own 73% with other stars for the numbers to count. The stacking would have to be precise for this to work if someone could actually come up with a pattern to deal with the huge numbers of 1 system and the inter mixing would be ridiculous. When you say 100 kpc, that just throws it out of the ballpark.


I'm not sure exactly what you're trying to say here. But, if I'm right in interpreting that what you're saying is that with the kind of relative sizes I've cited that it wouldn't work for stars to have dark matter halos, then you're on the right track. The sorts of considerations I've mentioned make it rather likely that dark matter won't be in bound orbits about individual stars, but rather will only be bound gravitationally to the galaxy as a whole. This, then, is why we don't see stars as having several times their visible mass.

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