are black holes stable?
How can a black hole be stable? It sucks all the matter towards it and it doesn't store it so either it must grow bigger and bigger as it takes more and more mater or it must convert it into energy which absorbs the matter again. If it does not do so then how can a black hole exist? though it would exist then it would not be stable. 
In general relativity, black holes are stable. "Sucking" is not an activity that consumes energy -- it is a property of matter to suck whether that mass is in a black hole or not. Newton described that as Universal Gravitation. The Earth would trace out the same orbit if the sun was removed and replaced with a same-mass black hole.
In quantum physics, black holes are metastable. In a perfectly empty and cold universe a black hole would evaporate over a very long period of time. By the time it is down to about a billion tons it is glowing brightly (for a tiny speck) and it gets hotter and hotter the more it shrinks. The final stages of this process are still being guessed at.
In our present universe, black holes the mass of stars (or larger) are much too cold to decay when bathed in the cosmic microwave background photon gas -- they absorb more energy than they radiate away.
In quantum physics, black holes are metastable. In a perfectly empty and cold universe a black hole would evaporate over a very long period of time. By the time it is down to about a billion tons it is glowing brightly (for a tiny speck) and it gets hotter and hotter the more it shrinks. The final stages of this process are still being guessed at.
In our present universe, black holes the mass of stars (or larger) are much too cold to decay when bathed in the cosmic microwave background photon gas -- they absorb more energy than they radiate away.
Then where does all the matter go?
Moreover does black holes really exist?
Moreover does black holes really exist?
QUOTE (hpdrdoom+Mar 8 2012, 09:33 PM)
are black holes stable?
The commonly known classical black hole solutions like the Schwarzschild solution, and Kerr-Newman solutions don't radiate if that's what you're asking. Its currently thought that a quantum effect radiation called Hawking radiation coming from very small black holes would make them immediately evaporate away, but large ones would be very stable regarding that effect as well. The classical Vaidya solution allows for electromagnetic radiance if that's what you're looking for.
The commonly known classical black hole solutions like the Schwarzschild solution, and Kerr-Newman solutions don't radiate if that's what you're asking. Its currently thought that a quantum effect radiation called Hawking radiation coming from very small black holes would make them immediately evaporate away, but large ones would be very stable regarding that effect as well. The classical Vaidya solution allows for electromagnetic radiance if that's what you're looking for.
QUOTE
Then where does all the matter go?
The classical solutions have it compressed to a point or ring of infinitesimal size of singular density. It depends on your quantum gravity theory to guess where it may really be.QUOTE (->
| QUOTE |
| Then where does all the matter go? |
The classical solutions have it compressed to a point or ring of infinitesimal size of singular density. It depends on your quantum gravity theory to guess where it may really be.
Moreover does black holes really exist?
Moreover does black holes really exist?
Since we've been finding them I'd say yes. The only real question is how close our theoretical black holes come in description to what we're actually observing in nature.
QUOTE (RealityCheck+Mar 9 2012, 09:43 PM)
Cheers...and back in a few days if I can!
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.... the stinking slug with club foot minded troll will no doubt materialize in the next few minutes, or my name's not Constantino.
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.... the stinking slug with club foot minded troll will no doubt materialize in the next few minutes, or my name's not Constantino.
A billion ton, non-rotating black hole, by widely accepted understanding, radiates about 13/30 gigawatts with a thermal spectrum corresponding to about 135 billion kelvin (gamma rays and some electrons and positrons). But even though it is steadily growing hotter and less massive it should persist more than 100 times longer than the current age of the universe.
(1 ton = 2000 lbs, about 907 kg, but you can put any mass into these formulae)
Overview
(1 ton = 2000 lbs, about 907 kg, but you can put any mass into these formulae)
Overview
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