History UsefulNotes / BlackHoles

21st May '18 9:51:33 PM TheBigBopper
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A black hole with a mass equal to the Earth (0.000003 solar masses) would have an event horizon whose radius was 0.000009 km, or 9 millimeters, ''or the size of your average American 25¢ quarter.''

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A black hole with a mass equal to the Earth (0.000003 solar masses) would have an event horizon whose radius was 0.000009 km, or 9 millimeters, ''or the size of your average American 25¢ quarter.1¢ penny.''
18th Apr '18 10:41:42 AM spydre
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* Magic: Black holes don't gain any super-magic powers of suction when they become black holes. Their mass exerts the same gravitational force as a star, planet, or any other object of the same mass. If our sun were suddenly turned into a black hole, nothing would happen to us. [[note]] other than the fact that all that energy normally radiated from the sun is suddenly gone[[/note]] Well, nothing would happen to the planet, though we'd most likely die off from cold and starvation. If we wanted to study a black hole, we could put a probe in orbit around it the same way we put probes around other astronomical bodies. It's not going to instantly spiral to its doom (at least not any faster than it would around anything else)[[note]]However since a black hole (except very massive ones) is ''far'' smaller than a star and does not emit radiation except very feeble Hawking radiation, the probe could be orbiting one at relatively close distances. However tidal forces aside that could destroy said probe unless the hole was large enough to have weak ones, below a certain point the probe would be unable to keep a stable orbit and would need to use an engine in order not to fall into the black hole (once that engine's fuel is used up, said goodbye to it)[[/note]] One rather clinching argument against the idea that you can't orbit a black hole is that, well, you're orbiting one now. Well, your Sun is, along with all the stars in the galaxy. So far, our galaxy has shown few signs of collapsing into oblivion. If you think about it, if black holes really did have such mystic suction powers, then they would have sucked everything in the universe into them by now.

to:

* Magic: Black holes don't gain any super-magic powers of suction when they become black holes. Their mass exerts the same gravitational force as a star, planet, or any other object of the same mass. If our sun were suddenly turned into a black hole, nothing would happen to us. [[note]] other than the fact that all that energy normally radiated from the sun is suddenly gone[[/note]] Well, nothing would happen to the planet, though we'd most likely die off from cold and starvation. If we wanted to study a black hole, we could put a probe in orbit around it the same way we put probes around other astronomical bodies. It's not going to instantly spiral to its doom (at least not any faster than it would around anything else)[[note]]However since a black hole (except very massive ones) is ''far'' smaller than a star and does not emit radiation except very feeble Hawking radiation, the probe could be orbiting one at relatively close distances. However tidal forces aside that could destroy said probe unless the hole was large enough to have weak ones, below a certain point the probe would be unable to keep a stable orbit and would need to use an engine in order not to fall into the black hole (once that engine's fuel is used up, said goodbye to it)[[/note]] One rather clinching argument against the idea that you can't orbit a black hole is that, well, you're orbiting one now. Well, your Sun is, along with all the stars in the galaxy. So galaxy, which, so far, our galaxy has shown few signs of collapsing into oblivion. If you think about it, if black holes really did have such mystic suction powers, then they would have sucked everything in the universe into them by now.
18th Apr '18 10:40:27 AM spydre
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* Magic: Black holes don't gain any super-magic powers of suction when they become black holes. Their mass exerts the same gravitational force as a star, planet, or any other object of the same mass. If our sun were suddenly turned into a black hole, nothing would happen to us. [[note]] other than the fact that all that energy normally radiated from the sun is suddenly gone[[/note]] Well, nothing would happen to the planet, though we'd most likely die off from cold and starvation. If we wanted to study a black hole, we could put a probe in orbit around it the same way we put probes around other astronomical bodies. It's not going to instantly spiral to its doom (at least not any faster than it would around anything else)[[note]]However since a black hole (except very massive ones) is ''far'' smaller than a star and does not emit radiation except very feeble Hawking radiation, the probe could be orbiting one at relatively close distances. However tidal forces aside that could destroy said probe unless the hole was large enough to have weak ones, below a certain point the probe would be unable to keep a stable orbit and would need to use an engine in order not to fall into the black hole (once that engine's fuel is used up, said goodbye to it)[[/note]]

to:

* Magic: Black holes don't gain any super-magic powers of suction when they become black holes. Their mass exerts the same gravitational force as a star, planet, or any other object of the same mass. If our sun were suddenly turned into a black hole, nothing would happen to us. [[note]] other than the fact that all that energy normally radiated from the sun is suddenly gone[[/note]] Well, nothing would happen to the planet, though we'd most likely die off from cold and starvation. If we wanted to study a black hole, we could put a probe in orbit around it the same way we put probes around other astronomical bodies. It's not going to instantly spiral to its doom (at least not any faster than it would around anything else)[[note]]However since a black hole (except very massive ones) is ''far'' smaller than a star and does not emit radiation except very feeble Hawking radiation, the probe could be orbiting one at relatively close distances. However tidal forces aside that could destroy said probe unless the hole was large enough to have weak ones, below a certain point the probe would be unable to keep a stable orbit and would need to use an engine in order not to fall into the black hole (once that engine's fuel is used up, said goodbye to it)[[/note]]
it)[[/note]] One rather clinching argument against the idea that you can't orbit a black hole is that, well, you're orbiting one now. Well, your Sun is, along with all the stars in the galaxy. So far, our galaxy has shown few signs of collapsing into oblivion. If you think about it, if black holes really did have such mystic suction powers, then they would have sucked everything in the universe into them by now.
25th Dec '17 12:41:14 PM tco3059
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Black holes are collapsed stars, but not many people know ''how'' the stars have collapsed in such a way to create black holes. We don't really understand what a singularity (the heart of a black hole) even is. When we try to do the math, key calculations utterly collapse and physics melts down as the space-time has infinite curvature. In other words, its mass has collapsed to, ''[[MindScrew paradoxically zero]]'' because its infinitely small, its volume infinitely dense, and its gravity is infinitely intense.

to:

Black holes are collapsed stars, but not many people know ''how'' the stars have collapsed in such a way to create black holes. We don't really understand what a singularity (the heart of a black hole) even is. When we try to do the math, key calculations utterly collapse and physics melts down as the space-time has infinite curvature. In other words, its mass has collapsed to, ''[[MindScrew paradoxically zero]]'' because its it's infinitely small, its volume infinitely dense, and its gravity is infinitely intense.
24th Aug '17 3:09:40 PM dieseldragons
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So, either way, you'll probably end up dead.

to:

So, either way, you'll probably end up dead.
dead (well, according to our classic understanding of it anyway, [[TemptingFate unless you dare to keep reading]]).


Added DiffLines:

And this is where things start to get '''even weirder'''. According to String Theory, black holes are actually "Fuzzballs", a ball of strings, bundles of energy vibrating in complex ways in both the three physical dimensions of space and compact directions—extra dimensions, interwoven in the quantum foam. This ties into Holographic principle. You are destroyed if you fall into one, and yet you are not. To resolve the information paradox, you are lost to the universe, but ''absorbed'' by the black hole. Ending up as a two-dimensional projection of your former three-dimensional self, trapped forever on the 'fuzzy event-horizon'. To the 3-D observer you are now 2-D, but you yourself would never ever know.

Some superstring theory scientists and physics theorize... ''this has already happened''. And that our entire true-3D or 4D universe has long fallen into a gargantuan black hole, and we ourselves are either in said black hole, or thanks to Quantum mechanics ensuring information can never be created or destroyed, '''a part of the phenomenon'''. We are all preserved within the universe's ultimate hard-drive.
24th Aug '17 2:50:18 PM dieseldragons
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Black holes are collapsed stars, but not many people know ''how'' the stars have collapsed in such a way to create black holes. We don't really understand what a singularity (the heart of a black hole) even is. When we try to do the math, key calculations utterly collapse and physics melts down as the space-time has infinite curvature. In other words, its mass has collapsed to, ''[[MindScrew paradoxically zero]]'' because its volume is infinitely small, its volume infinitely dense, and its gravity is infinitely intense.

to:

Black holes are collapsed stars, but not many people know ''how'' the stars have collapsed in such a way to create black holes. We don't really understand what a singularity (the heart of a black hole) even is. When we try to do the math, key calculations utterly collapse and physics melts down as the space-time has infinite curvature. In other words, its mass has collapsed to, ''[[MindScrew paradoxically zero]]'' because its volume is infinitely small, its volume infinitely dense, and its gravity is infinitely intense.
24th Aug '17 2:49:57 PM dieseldragons
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Black holes are collapsed stars, but not many people know ''how'' the stars have collapsed in such a way to create black holes. We don't really understand what a singularity (the heart of a black hole) even is. When we try to do the math, key calculations utterly collapse and physics melts down as the space-time has infinite curvature. In other words, its mass has collapsed to, ''[[MindScrew paradoxically zero]]'' because its infinitely small, its volume infinitely dense, and its gravity is infinitely intense.

to:

Black holes are collapsed stars, but not many people know ''how'' the stars have collapsed in such a way to create black holes. We don't really understand what a singularity (the heart of a black hole) even is. When we try to do the math, key calculations utterly collapse and physics melts down as the space-time has infinite curvature. In other words, its mass has collapsed to, ''[[MindScrew paradoxically zero]]'' because its volume is infinitely small, its volume infinitely dense, and its gravity is infinitely intense.
24th Aug '17 2:49:02 PM dieseldragons
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Black holes are collapsed stars, but not many people know ''how'' the stars have collapsed in such a way to create black holes.

to:

Black holes are collapsed stars, but not many people know ''how'' the stars have collapsed in such a way to create black holes.
holes. We don't really understand what a singularity (the heart of a black hole) even is. When we try to do the math, key calculations utterly collapse and physics melts down as the space-time has infinite curvature. In other words, its mass has collapsed to, ''[[MindScrew paradoxically zero]]'' because its infinitely small, its volume infinitely dense, and its gravity is infinitely intense.
7th Jul '17 2:11:23 AM Tightwire
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Black Holes don't actually, technically, emit anything, despite what people say about them emitting radiation[[note]]This may not be true. Due to quantum effects at the horizon, a black hole emits a form of black body radiation and very, VERY slowly loses mass until it eventually evaporates. However, the energy of the radiation 'emitted' by a black hole is inversely proportional to its mass. This means that lighter black holes can quickly evaporate in a burst of radiation; this also means that larger black holes won't be able to evaporate, or even lose mass, for quite some time, due to the cosmic microwave background. This form of radiation is called "Hawking radiation", named after its discoverer (well, "predictor" wold be more accurate, no one has ever actually been able to observe this radiation yet - due to obvious reasons) Stephen Hawking. You can read more about this in [[https://en.wikipedia.org/wiki/Hawking_radiation the other wiki]]. However, until irrefutable evidence is found, it's just a hypothesis despite the fact that it's mathematically all working out.[[/note]]. That's the extreme conditions the matter entering the black hole is subject to. If you heat something up, it will give off radiation. And the matter entering a black hole gets very, VERY hot with all the spinning and stretching and friction and gravity it's going through. Nothing leaves after it's past the Event Horizon itself. However because a black hole is just so awesome, the matter wouldn't achieve those conditions in any other way, so it kind of is, except it's not.

to:

Black Holes don't actually, technically, emit anything, despite what people say about them emitting radiation[[note]]This may not be true. Due to quantum effects at the horizon, a black hole emits a form of black body radiation and very, VERY slowly loses mass until it eventually evaporates. However, the energy of the radiation 'emitted' by a black hole is inversely proportional to its mass. This means that lighter black holes can quickly evaporate in a burst of radiation; this also means that larger black holes won't be able to evaporate, or even lose mass, for quite some time, due to the cosmic microwave background. This form of radiation is called "Hawking radiation", named after its discoverer (well, "predictor" wold be more accurate, no one has ever actually been able to observe this radiation yet - due to obvious reasons) Stephen Hawking. You can read more about this in [[https://en.wikipedia.org/wiki/Hawking_radiation the other wiki]]. However, until irrefutable evidence is found, it's just a hypothesis despite the fact that it's mathematically all working out.[[/note]]. That's the extreme conditions the matter entering ''entering'' the black hole is subject to. If you heat something up, it will give gives off radiation. And the matter entering a black hole gets very, VERY hot with all the spinning and stretching and friction and gravity it's going through. Nothing leaves after once it's past the Event Horizon itself. However because a black hole is just so awesome, unique in how it operates, the matter wouldn't achieve those conditions in any other way, so it kind of is, except it's not.
7th Jul '17 1:53:07 AM Tightwire
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Black holes are strange things. Besides the singularity at the center[[note]]Assuming it exists, since it's believed it's an artifact caused by breakdown of relativity under those conditions, that would disappear with a -still not existent- theory of quantum gravity[[/note]], there is the event horizon, the point of no return, that once you cross it...[[DepartmentOfRedundancyDepartment you can't return]]. Once inside the event horizon, you literally cannot go back: spacetime is curved in such a way by the black hole's mass that any path you take leads to the same place: the singularity. In three-dimensional space the Black Hole is not a disc. The singularity is an infinitely small point in space that sucks things in from all around, so the event horizon is more like a ball - with the singularity at the center. Rotating black holes also have an ergosphere: a region near the event horizon, where space-time spins around the black hole at speeds so great that you'd need to move faster than light just to stay still, let alone move in a direction counter to the black hole's rotation.

to:

Black holes are strange things. Besides the singularity at the center[[note]]Assuming it exists, since it's believed it's an artifact caused by breakdown of relativity under those conditions, that would disappear with a -still not existent- theory of quantum gravity[[/note]], there is the event horizon, the point of no return, that once you cross it...[[DepartmentOfRedundancyDepartment you can't return]]. Once inside the event horizon, you literally cannot go back: spacetime is curved in such a way by the black hole's mass that any path you take leads to the same place: the singularity. In three-dimensional space the Black Hole is not a disc. disc, just like the sun is not a big yellow circle. The sun is a sphere, an event horizon is a smaller sphere, and the singularity is an infinitely tiny ball so small point in space and tightly packed that sucks things in from all around, it has basically turned itself ''inside out'' - so when you are inside the event horizon is more like a ball - with singularity, you are inside the singularity at the center.ball. Rotating black holes also have an ergosphere: a region near the event horizon, where space-time spins around the black hole at speeds so great that you'd need to move faster than light just to stay still, let alone move in a direction counter to the black hole's rotation.
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