Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: neilep on 09/08/2009 12:35:35
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Dearest Blackholeologists,
As a sheepy I of course have oodles of Charisma and am very attractive. If ewe get close to my event horizon ewe ewe will never get away.
Look, here's a black hole:
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A Hole That Is Black
Nice eh ?..two being delivered next Tuesday as a pair of earrings !
Now then, black holes have things inside them at the middle that has infinite density and is infinitely small in size. Even smaller than a sand or a sugar and denser than my woolly fur when wet...(And that is well dense !)
What I would like to know is why does the singularity' just not gobble itself up ?..what with it being so dense and all that !...should it not just implode into nothingness ?..something must be stronger than the gravity field for it to remain substantial then eh ? If gravity is infinitely strong then should it not just pop out of existence ?
whajafink ?
Hugs & Shmishes Klever fizics peeps.
mwah mwah mwah !!
Neil
I have a Black Hole !
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I have always found this idea of a 'singularity' within a blackhole very strange, why simply because there is an event horizon should what is beyond it be of infinite density?.
Neutron stars come close to having a event horizon and I see no reason why further compression of matter cannot occur with no need for it to colapse to infinite density.
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I shudder at the thought of singularities. I'm sure they're just a mathematical tool for glossing over a hole in our knowledge and don't actually exist. I think there is some mechanism, as yet undiscovered, that prevents total collapse.
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I shudder at the thought of singularities. I'm sure they're just a mathematical tool for glossing over a hole in our knowledge and don't actually exist. I think there is some mechanism, as yet undiscovered, that prevents total collapse.
Agreed Beaver,....I see the stoppage of time as the limiting factor. As gravitational forces increase around a supermassive object, time slows down. If the gravity becomes strong enough to initiate the event horizon, 'the boundry beyond which light itself cannot excape' the passage of time stops. If this is the case, the contraction of the object will also stop. In my opinion, this extablishes a limit beyond which collapse cannot proceed.
Ofcourse, there may be issues that I have failed to consider. Hopefully, some of you can clear up this question for me.
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I believe there is a minimum size for blackholes as they evaporate, if the 'singularity' was of zero dimensions this would not be so.
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I believe there is a minimum size for blackholes as they evaporate, if the 'singularity' was of zero dimensions this would not be so.
Minimum size or maximum density? Or both?
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I don't think it's appropriate to use 'infinities' in connection with Black Holes because it's really a consequence trying to apply measurements inappropriately. If there is a point singularity at the center of a BH then there is zero volume, but you need non-zero volume for density. Although you might be able to mathematically divide something by zero, or divide zero by something, and get an answer of infinity, you can't expect to apply it to the real universe. For example, you could measure the amount of light coming in through a window, and then divide that by 0 and get a value of infinity. That value though, is meaningless to the light coming in through the window and will not affect it in any way. The answer is irrelevant. In the same way then, discussing the density of a point singularity is 'pointless' - density cannot apply to a point singularity.
Having said that though, I don't think it means that point singularities therefore cannot exist. Point singularities make a lot of sense in many ways, for if something cannot collapse to a point singularity then there must be a factor that prevents it and that factor needs to be not only identified but also held or stored somewhere, as well as having a mechanism by which it operates. Collapsing to a point singularity doesn't need any of this.
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If neutron stars can collapse even more to quark-stars, then in theory (and if string theory is correct) quark-stars could collapse to string-stars. Anyone able to do the math here? If you take the size of a string and pack a whole stars' worth all up tightly - how big would it be? I suppose such a star would not be very much different from a black hole, without the singularity-problem...
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I believe that in a black hole, open end strings (particles and forces) are converted to closed ringlike strings (gravitons).
This explains why it's black (photons converted to gravitons, so no light) and
why it can keep sucking matter to the center (once converted to gravitons, they can escape our universe and make room for more matter).
This probably also means that the density is not infinite, but at a critical point as to where conversion to gravitons starts.
This also means that if you have a really big anti-graviton particle gun, and blast it at the center of the black hole, you could go below the critical point and the black hole reverts to a superheavy, but dead star.
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I shudder at the thought of singularities. I'm sure they're just a mathematical tool for glossing over a hole in our knowledge and don't actually exist. I think there is some mechanism, as yet undiscovered, that prevents total collapse.
My feelings exactly, DoctorBeaver, and I even have a mechanism to suggest. What if gravity affects gravity the way gravity affects light. This is a natural assumption for me since I suspect that gravity is an electromagnetic phenomena. So if this were so, the stronger the gravitational field, the weaker would be the effect of any additional gravitating mass. It would be self limiting and so eliminate the possibility of a singularity.
Also, though its a little difficult to get your mind around it, acceleration due to gravity has time as a constituent. Time is affected by gravity. So acceleration due to gravity is affected by gravity and so would be self limiting.
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What I would like to know is why does the singularity' just not gobble itself up ?..what with it being so dense and all that !...should it not just implode into nothingness ?..something must be stronger than the gravity field for it to remain substantial then eh ? If gravity is infinitely strong then should it not just pop out of existence ?
Infact this is what some physicists think it should happen [:)]
Anyway BH are still a too complicated subject for me; to discuss properly about them would require a good knowledge of general relativity (which I don't have...)
As other posters of this thread I've never understood well why the implosion should continue forever. Once I read something about the fact that "cones of light" of the events in spacetime tilt, inside the horizon, so every point mass must continue its fall down (or something about that...)
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is the idea of another universe much like our own inside a black hole a possibility or is it ridiculous?
what if the edges of our universe are (to another observer in another universe in which our black hole is contained) the edges of a black hole? they would never be able to see us, and we wouldn't be able to see them, but that's how it would look, surely?
if light has mass, and if the speed of light is the maximum speed anything can go (besides expansion of space itself), then doesn't this offer a reason why black holes are spherical? the light itself alters the space-time of the edges of the universe, so it really would be like a giant ball that's expanding. surely light must be involved in the shaping of the furthest possible edges of the universe, as it's the mass that can travel the furthest..
to an outside observer, the sphere would remain at a constant size (which i believe is true for black holes) as light cannot escape it while the stuff inside the black hole expanded to an observer inside the black hole. this would elegantly explain the creation of new universes, including our own, would it not? the big bang would have been a star collapsing in another universe, and the singularity was created. it also explains why very small black holes would evaporate - the mass that they had would not be very strong, which would not lead to a big bang but rather a smaller bang, and eventually a big crunch. black holes above a certain mass would end in the big freeze.
or is this again, just ridiculous? i have no idea. i'd like to know though ^^
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I agree with others. Its just a mathematical fudge created by mathematicians who love to try and complicate even the simplest of things.
I don't believe that a black hole contains a singularity or any mass whatsoever. I see it as just a hole in space that contains nothing, no hypothetical particles such as gravitons, no photons, no Hawking radiation and no mass in the centre. A one way vortex membrane that sucks (bad word) matter in and deposits it elsewhere on the other side of the hole.
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The possibility of Black Hole existence comes from GR. I don't think GR says anything about Black Holes being exit portals for this universe. IMHO after your thinking gets past the event horizon, it is all speculation after that. [:)]
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That thinking leads to an event horizon first and then a singularity. What some have suggested so far is that the singularity does not exist so the idea of any event horizon cant either. If that is the case then a black hole does not have to contain that much mass.
What I suggested has nothing to do with exit portals for this universe only that matter could be funnelled through the vortex and deposited elsewhere. As a vortex goes its usually only one way, a bit like a "Dyson" cleaner.
So to answer neilep, I don't think there is infinite density to a black hole and that's why it don't destroy itself. [:)]
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Hawking radiation (also known as Bekenstein-Hawking radiation) is a thermal radiation with a black body spectrum predicted to be emitted by black holes due to quantum effects. It is named after the physicist Stephen Hawking who provided the theoretical argument for its existence in 1974, and sometimes also after the physicist Jacob Bekenstein who predicted that black holes should have a finite, non-zero temperature and entropy. Hawking's work followed his visit to Moscow in 1973 where Soviet scientists Yakov Zeldovich and Alexander Starobinsky showed him that according to the quantum mechanical uncertainty principle, rotating black holes should create and emit particles. The Hawking radiation process reduces the mass of the black hole and is therefore also known as black hole evaporation.
Because Hawking radiation allows black holes to lose mass, black holes that lose more matter than they gain through other means are expected to dissipate, shrink, and ultimately vanish. Smaller micro black holes (MBHs) are predicted to be larger net emitters of radiation than larger black holes, and to shrink and dissipate faster.
Source: http://en.wikipedia.org/wiki/Hawking_radiation (http://en.wikipedia.org/wiki/Hawking_radiation)
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Hawking radiation has been predicted but never observed so its not actually a fact to be relied on. Its a good theoretical argument, been changed a bit and still subject to change.
Maybe they will find it but so far its not proven to exist when it should. [:)]
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I wonder if we know enough about Hawking Radiation to recognize it if we see it. If it is a product of vacuum fluctuations where a particle-antiparticle pair is created and one gets caught up in the black hole, what distinguishing characteristic would the escaping particle have?
Maybe there's a sign on it that says "I just escaped a Black Hole"???
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I wonder if we know enough about Hawking Radiation to recognize it if we see it. If it is a product of vacuum fluctuations where a particle-antiparticle pair is created and one gets caught up in the black hole, what distinguishing characteristic would the escaping particle have?
Maybe there's a sign on it that says "I just escaped a Black Hole"???
Ha,ha,ha,ha.....That's a good one Vern. I personally think there could never be any way to really distinguish between the escaping virtual and the surrounding ambient fluctuations.
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I guess maybe if we noticed gamma radiation at around .510 MeV that comes from some black-hole candidate we might assume it to be Hawking radiation. It would come from positron-electron inhalation in proximity to the candidate.
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I guess maybe if we noticed gamma radiation at around .510 MeV that comes from some black-hole candidate we might assume it to be Hawking radiation. It would come from positron-electron inhalation in proximity to the candidate.
But the tricky thing about Hawking radiation, according to stephen himself, is that it will be a random radiation. All information will be lost, so you'll never know from what reaction or what not the radiation is coming from.