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Author Topic: Are there any theories about why a singularity could go dormant with mass close?  (Read 1194 times)

Offline Joe Boboblob

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I'm just an uneducated human who is really fascinated by black holes. So please dumb down your answer.

It's my understanding that there has been at least one observed case of a black hole being dormant with plenty of matter available for absorption. I've read that a black hole has an eddington limit, which is how much it can absorb at once before light/heat from this absorption process pushes matter away, but this does not explain why a black hole would be dormant with matter nearby - it would only explain why it could only absorb so much of the matter in a given time.

Bonus question: There's an interesting theory about how each black hole could contain a universe inside of it. I'm guessing that the general consensus is 'that's rubbish'. Still, if it is being entertained, are there any theories about how one black hole consuming another would be perceived by an observer inside either black hole? If not, do you have one? I know, I know, I'm asking 'what if this crazy theory about this poorly understood thing, and this irregular and poorly understood event occurring with said theory in mind.' While I'm interested in any theory that meets that criteria above, I'm specifically curious as to whether there may be any reason/theory substantiating why this would cause the universe to appear to be expanding exponentially? That'd be interesting as, in my mind, it'd add credibility to the 'father' theory. In this aforementioned theory, each black hole would have different spacetime. The concept of spacetime changing isn't new though - it's already been hypothesized that two supermassive black holes merging could alter spacetime (of the parent black hole, or the one that we're in now, under this theory)

Bonus question two: People say that black holes don't release anything (just hawkings radiation). Bill Nye said that throwing a black hole at a black hole wouldn't solve anything as it would only grow in size. However, while two black holes colliding seems to result in a larger black hole, I've read that this would cause a huge amount of energy to be released. It's been said that it'd be a galaxy-crushing amounts in the event of two supermassive black holes combining. Because of a certain equation that we all know, doesn't this mean that black holes colliding results in some amount of matter leaving them?

« Last Edit: 02/12/2015 04:30:21 by Joe Boboblob »


 

Offline puppypower

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Here is my theory, which is not mainstream.

If you were inside a blackhole, since space-time is highly contracted; fuzzy singularity, if you could look out at the universe, distant things in the universe would appear very close, due to the extreme distance contraction. Theoretically, all the black holes of the universe, by having references close to C; fuzzy singularity, can see each other, all clumped locally. They appear close because their references are all contracted while being birds of a feather.

In other words, if you traveled at the speed of light, the universe will appear to be contained in a point. This reference will make all the black holes appear like one big black hole. Blackholes do not see this, but rather they see the universe slightly bigger, because they are fuzzy singularities; work in progress.

If you started at the speed of light the entire universe will appear like a point, where all distinctions we can see in space appear to merge into that point. One can't tell one galaxy from another galaxy. If we slow slightly, a distinct will appear called black holes. Their internal reference is so close to  C, they will appear as the first reference distinction one would see slowing from C.

Each blackhole will see all their fellow blackholes of the universe, nearby due to distance contraction of points. This close reference clustering also have high time dilation. This allows them to work as a team, in their own time and place, since they all have the same goal in mind, which is to compact matter so the matter can see what they see. Sometimes the team can shift priority so some black holes appear to slack and other become busy.
 

Offline Joe Boboblob

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This allows them to work as a team, in their own time and place, since they all have the same goal in mind, which is to compact matter so the matter can see what they see. Sometimes the team can shift priority so some black holes appear to slack and other become busy.

That sounds like you're saying black holes are sentient? I think that would be a bit of a stretch.
 

Offline Space Flow

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I have to agree entirely with Puppypower.
If Black Holes were considered the observers, (note I'm laying no claim to sentience) they would see each other within their Gravitationally bound system. All dancing around each other clearing their orbits. Of course the entirety of the Universe from start to finish, might not represent much more than a temporary extended flash to that frame of reference.
 


Offline evan_au

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Quote from: Joe Boboblob
a singularity
A singularity is the theoretical point at the center of a black hole where density approaches infinity.

However, even if we could get close to a black hole, we wouldn't see the singularity itself, because the event horizon defines a surface around the singularity where even light cannot escape.

It is hard to study black holes because (fortunately), there don't seem to be any in our immediate neighborhood. However, studying the behavior of the singularity is far harder again.

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why could a singularity go dormant with mass close?
There is a black hole at the center of our galaxy (or something that acts very much like a black hole would) with an estimated mass around 4 million times the mass of the Sun.

There is a dense concentration of stars at the center of the galaxy, and some stars have been tracked for 16 years of their orbit around this black hole.


For as long as the gravitational attraction of the star exceeds the gravitational attraction of the black hole, the gas of the star will remain with the star. The star will continue on its orbit, taking it far from the black hole. There will be very little gas on which the black hole can feed,  and the black hole will remain dormant.

However, if a star's orbit takes it inside the Roche limit, the star will be torn apart, and the gas will form an accretion disk around the black hole. Frictional forces will cause the gas to get extremely hot, and most of the gas to spiral down into the black hole. A small fraction of the matter will be expelled along the axis of rotation, at close to the speed of light. When the matter in the accretion disk has fallen into the black hole, the black hole will again go dormant until some other hapless star passes too close.

A black hole swallowing a star causes the black hole to become active for a period of a month or so. The jets of matter are visible to radio telescopes for a longer period. This whole process has recently been observed in another galaxy.

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two black holes colliding ...would cause a huge amount of energy to be released.
It is thought that matter falling into a black hole would reach speeds up to 30% of the speed of light, and could release up to 30% of their mass-energy. Some of this is radiated as X-rays from the accretion disk, and more is radiated in the polar jets. The polar jets don't escape from within the event horizon, but from the accretion disk just outside the event horizon.

Black holes the mass of the Sun and larger don't actually release any matter (beyond the Hawking radiation, which is almost at a temperature of absolute zero for black holes in this size range).

So two black holes merging would not release energy in the same way as matter falling into a black hole. Most of the energy from a black hole merger would be released in the form of gravitational waves. While gravitational waves have proven very elusive so far for researchers on Earth, I imagine it would be a very rocky road in the vicinity of merging black holes!

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It's been said that it'd be a galaxy-crushing amounts in the event of two supermassive black holes combining.
There are candidates identified for the merger of two galactic black holes, the so-called X-shaped radio galaxies. It appears that the angle of the polar jets has suddenly shifted, as if the axis of rotation of the central black hole has suddenly changed. The most likely cause of this would be a collision with another large black hole having a different axis of rotation.

However, the galaxies seem to have survived this cosmic collision, and they continue to emit jets of matter from the center of the galaxy. So while this event would undoubtedly be very dramatic for anyone in that galaxy, "galaxy-crushing" might be a bit of an exaggeration.
 

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