History UsefulNotes / BlackHoles

14th Jul '16 11:05:28 AM MsChibi
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# You reverse yourself in time, but fail to move in space. You think you are outside the Black Hole, and so does your magical FTL ship, but you're not. Eventually you hit the singularity and disintegrate, but you don't even notice. You are dead.

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# You reverse yourself in time, but fail to move in space. [[LotusEaterMachine You think you are outside the Black Hole, and so does your magical FTL ship, but you're not.not]]. Eventually you hit the singularity and disintegrate, but you don't even notice. You are dead.
1st Jun '16 10:25:59 PM AnotherGuy
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Have fun arguing with infinity.

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In fact, it's been noted that black holes are nature's way of [[RealityBreakingParadox dividing by zero]]. Have fun arguing with infinity.
16th May '16 10:51:21 AM BurgerLord
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# The desired scenario - you appear outside the Black Hole with full memory of your experience and data in hand, you don't go in again, and the universe somehow doesn't switch off. Congratulations, not only have you rewound ''the entire universe except yourself,'' defying all laws of physics, but you have defied all possible logic too. You are now God. Or possibly [[Series/DoctorWho The Doctor]].

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# The desired scenario - you appear outside the Black Hole with full memory of your experience and data in hand, you don't go in again, and the universe somehow doesn't switch off. Congratulations, not only have you rewound ''the entire universe except yourself,'' defying all laws of physics, but [[RealityWarper you have defied all possible logic logic]] too. You are now God. Or possibly [[Series/DoctorWho The Doctor]].
7th May '16 4:27:50 AM ScorpiusOB1
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Right now there's no strict proof that such things exist: granted, there ''are'' heavy low-radiating objects ("black hole candidates"), but whether some low-emission star inside an enormous gas and dust cloud is really a black hole or not... Yet, there is one [[http://arxiv.org/abs/0903.1105 article]], that states: Sagittarius A* (a source of radio waves, associated with a supermassive object in the center of the Milky Way) must have an event horizon because, given the amount of superhot infalling matter we've detected around it, its surface luminosity is too low to be explained ''without'' something that traps radiation.

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Right now there's Until February 2016, with the [[https://en.wikipedia.org/wiki/First_observation_of_gravitational_waves first detection of gravitational waves]] with the LIGO instrument[[note]]It has the bonus of having too proved the existence of black holes, since the detected signal exactly matches the theoretical predictions of a black hole merger[[/note]], there was no strict proof that such things exist: granted, there ''are'' heavy low-radiating objects ("black hole candidates"), but whether some low-emission star inside an enormous gas and dust cloud is really a black hole or not... Yet, there is one [[http://arxiv.org/abs/0903.1105 article]], that states: Sagittarius A* (a source of radio waves, associated with a supermassive object in the center of the Milky Way) must have an event horizon because, given the amount of superhot infalling matter we've detected around it, its surface luminosity is too low to be explained ''without'' something that traps radiation.
29th Mar '16 1:41:34 PM AnotherGuy
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Added DiffLines:

There is one last part about black holes that is still very controversial, the [[https://en.wikipedia.org/wiki/Black_hole_information_paradox Black Hole Information Paradox]]. That is, what ''happens'' to information when in a black hole. Hawking stated that it's irretrievably lost, which would violate the [[https://en.wikipedia.org/wiki/First_law_of_thermodynamics First Law of Thermodynamics]] - however, thanks to the bizarre nature of black holes, it's possible the law might be broken (thank you, infinity). Other theories include it being hidden in a "pocket universe" or it's released when the black hole eventually evaporates, regardless of its size.
9th Feb '16 7:45:44 PM DKN117
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Lighter stars become a degenerate-matter white dwarf which slowly cools over trillions of years into a black dwarf[[note]]Not to be confused with "brown dwarfs", which are substellar bodies, like large planets, that were never massive enough to sustain fusion to begin with.[[/note]]. According to current estimates, no black dwarfs yet exist, as a star cooling to that level would take longer than the universe has existed. The Sun is expected to become a black dwarf in approximately 1 quadrillion years. Stars with more than 1.4 times the mass of the sun have exceeded the "Chandrasekhar limit" and gravity combines electrons and protons to form neutrons, resulting in a neutron star. Stars whose mass exceeds the Tolman-Oppenheimer-Volkoff limit (about two to three solar masses, and definitely no more than five, but it's still unclear) are so massive that even the neutrons can't resist further collapse;[[note]]Neutron stars are prevented from collapsing further by a pressure called neutron degeneracy pressure. This is caused by the Pauli exclusion principle, and the degeneracy pressure is insufficient to prevent collapse over the Tolman-Oppenheimer-Volkoff. However, it is possible that there are other forms of degenerate matter, which may be capable of preventing further collapse until the object's mass reaches a new limit.[[/note]]it can be assumed that the star collapses down to the event horizon, and past it to a singularity (a single point, or a ring for a rotating black hole).

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Lighter stars become a degenerate-matter white dwarf which slowly cools over trillions of years into a black dwarf[[note]]Not to be confused with "brown dwarfs", which are substellar bodies, like large planets, that were never massive enough to sustain fusion to begin with.[[/note]]. According to current estimates, no black dwarfs yet exist, as a star cooling to that level would take longer than the universe has existed. The Sun is expected to become a black dwarf in approximately 1 quadrillion years. Stars with cores weighing in at more than 1.4 times the mass of the sun have exceeded the "Chandrasekhar limit" and gravity combines electrons and protons to form neutrons, resulting in a neutron star. Stars whose core mass exceeds the Tolman-Oppenheimer-Volkoff limit (about two to three solar masses, and definitely no more than five, but it's still unclear) are so massive that even the neutrons can't resist further collapse;[[note]]Neutron stars are prevented from collapsing further by a pressure called neutron degeneracy pressure. This is caused by the Pauli exclusion principle, and the degeneracy pressure is insufficient to prevent collapse over the Tolman-Oppenheimer-Volkoff. However, it is possible that there are other forms of degenerate matter, which may be capable of preventing further collapse until the object's mass reaches a new limit.[[/note]]it can be assumed that the star collapses down to the event horizon, and past it to a singularity (a single point, or a ring for a rotating black hole).
26th Jan '16 1:37:49 PM FordPrefect
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Unless you're watching ''extremely'' hard SciFi ([[MohsScaleOfScienceFictionHardness like 5.5 or 6]]), a black hole is probably nothing like you've generally seen in fiction. Black holes rank up there with FTL and TimeTravel as one frequently exploited bits of science.

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Unless you're watching ''extremely'' hard SciFi ([[MohsScaleOfScienceFictionHardness like 5.5 or 6]]), a black hole is probably nothing like you've generally seen in fiction. Black holes rank up there with FTL and TimeTravel as one of the most frequently exploited bits of science.
26th Jan '16 1:37:25 PM FordPrefect
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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 is ''far'' smaller than a star and does not emit radiation except very faint Hawking radiation, the probe could orbit it much closer. Tidal forces aside, that if it's too close to the hole could destroy the probe, this means if orbits very close, it could be unable to leave its orbit unless it had a very powerful engine.[[/note]]

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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 is ''far'' smaller than a star and does not emit radiation except very faint Hawking radiation, the probe could orbit it much closer. Tidal forces aside, that if it's too close to the hole could then itcould destroy the probe, this means so if it orbits very close, it could be unable to leave its orbit unless it had a very powerful engine.[[/note]]
26th Jan '16 1:36:26 PM FordPrefect
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* Black: Oh sure, it's black beyond what looks like the horizon, but it may well glow brightly from heat generated by whatever it is that they're sucking in, and from accretion. [[http://www.wired.com/wp-content/uploads/2014/10/ut_interstellarOpener_f.png A real black hole might look more like this]] if enough matter has gone in. And even then, the black isn't anywhere you can fall into; you won't even know when you've fallen in the real event horizon, assuming you haven't already been torn apart by tidal forces.
* Flat: Staying away from the more [[TimeyWimeyBall wibbly-wobbly]] stuff, it's convenient to think of a black hole as a tiny sphere and the event horizon is a shell around it. Once you hit the shell, you're stuck. It's also going to look pretty much exactly the same as you circle it, regardless of the direction you chose. The objects orbiting it do so due to spin.

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* Black: Oh sure, it's black beyond what looks like the horizon, but it may well glow brightly from heat generated by whatever it is that they're sucking in, and from accretion. [[http://www.wired.com/wp-content/uploads/2014/10/ut_interstellarOpener_f.png A real black hole might look more like this]] if enough matter has gone in. And even then, the black isn't anywhere you can fall into; you won't even know when you've fallen in through the real event horizon, assuming you haven't already been torn apart by tidal forces.
* Flat: Staying away from the more [[TimeyWimeyBall wibbly-wobbly]] stuff, it's convenient to think of a black hole as a tiny sphere and the event horizon is as a shell around it. Once you hit the shell, you're stuck. It's also going to look pretty much exactly the same as you circle it, regardless of the direction you chose. The objects orbiting it do so due to spin.
26th Jan '16 1:29:59 PM FordPrefect
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However, you'd probably be long dead before that anyway, as black holes come with some dangers attached due to the infinite gravity they exert: First, you'll be spaghettified (this ''is'' the scientific term for it); the tidal forces of the black hole are so strong that, if you were going in feet first, your feet would feel a stronger attraction than your head and thus your body would stretch out (incidentally, this occurs in more applicable situations, such as returning space shuttles, as well - the difference is that the attraction difference is so minor that the astronauts do not stretch a measurable amount). The gravity exerted by black holes is so strong that it can even deform atoms. On the upside, the bigger a black hole is, the less drastic this effect becomes on its edge; in fact, for a supermassive black hole, an individual should survive at least past the event horizon[[note]]For less massive ones, you'll be dead before you even cross the event horizon[[/note]]. The second big danger is good old radiation, due to gravitational blueshifting. Any radiation hitting you from the outside would be blueshifted (given higher frequencies, and therefore energy, as opposed to redshifting, which decreases the frequency of electromagnetic radiation and therefore their energy) and thus a lot more dangerous, to the point that, [[http://jila.colorado.edu/~ajsh/insidebh/realistic.html according to some simulations]], it would be the thing that would kill you before you could reach the singularity, assuming a black hole big enough to neglect tidal effects. The thing is known as ''[[http://discovermagazine.com/2011/jun/26-strange-physics-singular-views-inside-black-holes/article_view?b_start:int=2&-C= inflationary instability]]'' and, according to scientists, [[ThereIsNoKillLikeOverkill its effects would go very far beyond of just vaporizing your body.]]

to:

However, you'd probably be long dead before that anyway, as black holes come with some dangers attached due to the infinite gravity they exert: First, you'll be spaghettified (this ''is'' the scientific term for it); the tidal forces of the black hole are so strong that, if you were going in feet first, your feet would feel a stronger attraction than your head and thus your body would stretch out (incidentally, this occurs in more applicable situations, such as returning space shuttles, as well - the difference is that the attraction difference is so minor that the astronauts do not stretch a measurable amount). The gravity exerted by black holes is so strong that it can even deform atoms. On the upside, the bigger a black hole is, the less drastic this effect becomes on its edge; in fact, for a supermassive black hole, an individual should survive at least past the event horizon[[note]]For less massive ones, you'll be dead before you even cross the event horizon[[/note]]. The second big danger is good old radiation, due to gravitational blueshifting. Any radiation hitting you from the outside would be blueshifted (given higher frequencies, and therefore energy, as opposed to redshifting, which decreases the frequency of electromagnetic radiation and therefore their energy) and thus a lot more dangerous, to the point that, [[http://jila.colorado.edu/~ajsh/insidebh/realistic.html according to some simulations]], it would be the thing that would kill you before you could reach the singularity, assuming a black hole big enough to neglect tidal effects. The thing is known as ''[[http://discovermagazine.com/2011/jun/26-strange-physics-singular-views-inside-black-holes/article_view?b_start:int=2&-C= inflationary instability]]'' and, according to scientists, [[ThereIsNoKillLikeOverkill its effects would go very far beyond of just vaporizing your body.]]
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