Black Holes

[jasonatron]

It is stated in most scientific texts that what ever goes into a black hole never comes back out. I was wondering if this is absolutely true. Is it not possible that it just takes a very long time and then suddenly all of the mass that has been "gobbled up" by the black hole will suddenly be ejected? Are there any known instances in the universe of areas of space that spew mass? If so, could these be former black holes?

[pywakit]

It is stated in most scientific texts that what ever goes into a black hole never comes back out. I was wondering if this is absolutely true. Is it not possible that it just takes a very long time and then suddenly all of the mass that has been "gobbled up" by the black hole will suddenly be ejected? Are there any known instances in the universe of areas of space that spew mass? If so, could these be former black holes?

 

To my knowledge ... no. There is no evidence of 'spewing mass', as in a black hole suddenly ejecting all it's mass. There is no evidence of 'former' black holes.

 

Hawking has been trying to prove for over 30 years that black holes 'leak' particles, and that this leakage will eventually make the black hole 'dissipate'. You might want to check into his research.

 

There is a wealth of new information available on black holes from many respected sites such as NASA.

 

As far as the highlighted section goes, there are many theories on what black holes may or may not do. This is a very heated topic/debate among cosmologists, astrophysicists, and physicists.

 

I suggest you google "cosmological models of the universe".

 

Good luck.

 

(edit) I should also point out ... in fairness ... that although most mainstream scientists feel that the existence of black holes has been overwhelmingly proved, there are some who do not agree and feel the evidence has been misinterpreted.

 

In addition, I have no science degree, so perhaps you will get a more intelligent response from the actual scientists here.

Edited January 8, 2010 by pywakit

[truedeity]

Here is my answer on this. http://whoarethegreys.com/Untitled.wmv

[pywakit]

Here is my answer on this. http://whoarethegreys.com/Untitled.wmv

 

I just watched 7 minutes of that video. Would you mind explaining what ANY of that had to do with the OP's questions?

 

Good grief.

[liarliarpof]

The painfully slow emission of 'Hawking Radiation' is an accepted mechanism by which the miserly hole returns what has been devoured. And, yes, it is really, really, really slow process. See the book, "Black Hole Wars - My Battle With Stephen Hawking and Keeping The World Safe for QM" by Leonard Susskind. Otherwise, to the best of my knowledge, no spewing but perhaps the dry heaves which, like the Golem itself, would not be observable.

[toastywombel]

I just watched 7 minutes of that video. Would you mind explaining what ANY of that had to do with the OP's questions?

 

Good grief.

 

I watched the same video and commented on it in another thread here.

 

Are we in another hawking radiation debate here?

[ajb]

The problem with Hawking radiation is that it is thermal. One can say that it does not care what you feed into the black hole. The properties of the in falling particles is not seen in radiation.

 

The big question is what happens at the final point of evaporation?

[toastywombel]

The problem with Hawking radiation is that it is thermal. One can say that it does not care what you feed into the black hole. The properties of the in falling particles is not seen in radiation.

 

The big question is what happens at the final point of evaporation?

 

I am starting to wonder if there is a final point of evaporation. Observations of black holes show that the more massive they are (mass inside the event horizon) the less dense they are. While the less massive black holes are higher density.

[ajb]

Well, all the work on Hawking radiation is based on semiclassical gravity. That is one works with quantum fields on a classical curved space-time. This gives a window into possible phenomenology of a full quantum theory of gravity.

 

However, I would expect the final stages of black hole evaporation to be dependent on the exact nature of quantum gravity. Semiclassical gravity is probably not sufficient. Thus, it is not known what happens near the point of evaporation at the present time.

[vordhosbn]

What do you mean by "density of the black hole", i thought the black hole is a part of the space time which is so warped by gravity that nothing escapes, with all of its matter collapsed in a singularity with no volume. So how can it have density?

[Sisyphus]

What do you mean by "density of the black hole", i thought the black hole is a part of the space time which is so warped by gravity that nothing escapes, with all of its matter collapsed in a singularity with no volume. So how can it have density?

 

That's right. The black hole itself would be a single point of infinite density. toastywombel is probably talking about the volume inside the event horizon. The radius of the event horizon is directly proportional to the mass of the black hole, so the volume inside would increase with the cube of the mass. However, I don't know what significance if any this "density" would have to the question at hand.

[vordhosbn]

Actually if i remember correctly, if the black hole is spinning fast enough, the singularity can strech to a disk (still with zero height and hence - zero volume).

[ajb]

I think you might be referring to the apparent singularities of the Kerr metric, that is the spherical event horizon and the outer boundary of the ergosphere.

 

You can have more exotic things like black rings in general relativity with 5 dimensions or higher.

[jasonatron]

My original thought, though I'm not a physicist, was that maybe the mass associated with a black hole oscillates in and out of the black hole over very large time frames. However if there is no mass "spewing" to our knowledge anywhere in the observable universe, then I guess this can't be the case.

[lucky45]

As of up to date knowledge, No one has ever seen a black hole. Even the one that is predicted to be in the center our own galaxey. Black holes ,if there is one ,Are only based on certain anomalies,that occur in the universe.

As far as being gobbled up, only one can be shure if they go into one, If you do,Let me knoe whats on the otherside Ha

[SunEatsCloud]

What about the life and death of a black hole? Has the death of a black hole ever been observed? The fact that they don't release any energy (that we can observe, at least) could mean that they simply don't use any. Maybe in the state of singularity they become somehow stable.

 

Or maybe their appetite keeps them from running out of energy.

 

But I've never read deep into the topic of black holes. So I'm just making guesses. Anyone know anything more?

[liarliarpof]

I recall that the story went that when the hole begins to only radiate (in some uber-distant epoch, after it has cleaned out the pantry), as it 'shrinks', the emision rate increases at an increasingly accelerated pace, the smaller the hole becomes. When it reaches Planck Scale, ? Now you don't see it, now you don't!

[eoinmac]

My best guess is that the hawking radiation emitted from the black hole accumulates over huge time scales and then they suddenly 'disappear' like the black holes that some hypothesize enter and depart from existence almost instantaneously. There would most likely not be some huge explosion of energy or particles because most of the mass (energy) of the black hole has already escaped into space via hawking radiation. Just a guess

[toastywombel]

I am getting the feeling that many of you are assuming that black holes get smaller in size. So far observations tell us that black holes always become larger in diameter as they grow more massive.

[eoinmac]

I am getting the feeling that many of you are assuming that black holes get smaller in size. So far observations tell us that black holes always become larger in diameter as they grow more massive.

 

 

Good point, i should clarify that the black hole i had in mind was not surrounded by matter such as a black in a galactic center but more in open space