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Stephen Hawking on Black Holes: There is No Such Thing as an Event Horizon
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WeAreStarStuff
Member
What are the implications of this in regards to white holes?
http://www.reddit.com/r/askscience/...f_the_event_horizons_of_two/c1cuiyw?context=2
As for the math behind the black hole:
http://en.wikipedia.org/wiki/Schwarzschild_metric#Singularities_and_black_holes
Essentially, it's the solution to the einstein field equations for a spherical mass where the math blows up (because you end up dividing by 0)
Omegasquash
Member
Aren't white holes still hypothetical?
WeAreStarStuff
Member
Yes.
Account Attempt #4
Member
Bifurcated down until you're nothing but a stream of atoms racing toward the center. Ain't that some shit.
That is golden gif material. Change Ship for thread and add Bish head
backflip10019
Member
Black holes are endlessly fascinating and I in no way have any understanding of them even after reading the OP and watching documentaries about them.
ClassyPenguin
Banned
Susskind is a g.
Came for this, ty.
I don't think hiding under the bed is going to help much
Sapphire Dreams
Member
Actually, many theories propose that black holes were essentially gigantic stars but collapsed in on itself when they went supernova. A black hole is a space so dense that has a huge gravity that nothing, not even light can escape it.
Considering the crap movies get away with with respect to computers, I don't imagine a movie being a little inconsistent with cutting edge astro physics will really be that much of a problem for the audience.
Oh, I see. *KABOOOM*
Albino_Samurai
Member
Gravity.
Where's my damn sequel?? Starck never saw Weir's final form, yet her vision upon being brought out of deep sleep was in fact what Weir looked like before Miller blew up the ship. The only way she would be able to see his face like that was if the escape pod was possessed as well (considering it was a part of the ship before it made the jump), meaning once that bad boy was taken back to earth, all sorts of hell should've broken loose.
The way I understand it is that black holes "grow" because matter falls into them faster then they evaporate. Eventually, because of "heat death" black holes will evaporate completely because there is no longer enough material in the universe to sustain them.
This is a fun, quick read: http://math.ucr.edu/home/baez/physics/Relativity/BlackHoles/fall_in.html
This is a fun, quick read: http://math.ucr.edu/home/baez/physics/Relativity/BlackHoles/fall_in.html
Kitschkraft
Member
Sensational journalism at its best. The actual quote from him "There are no black holes," the paper concludes, "in the sense of regimes from which light can't escape to infinity."
Of course all that gets quoted is the first part. He isn't saying that the entities we refer to Black Holes don't exist, rather how we understand them is flawed.
Of course all that gets quoted is the first part. He isn't saying that the entities we refer to Black Holes don't exist, rather how we understand them is flawed.
So do most people (when young, that is).
well then. Pack it up science. You had a good run.
Guerrillas in the Mist
Member
GAF never disappoints.
did you know a white hole can turn spaghetti into an astronaut?
Mgoblue201
Won't stop picking the right nation
It's not so much Hawking's radiation theory that was "shot down", but rather his views pertaining to the black hole information paradox. I'm going to extensively quote From Eternity to Here by Sean Carroll (which I recommend as a challenging but accessible introduction to modern physics) to explain the idea behind Hawking radiation:
What Hawking figured out is that the gravitational field of a black hole can turn virtual particles into real ones. Ordinarily, virtual particles appear in pairs: one particle and one anti-particle. They appear, persist for the briefest moment, and then annihilate, and no one is the wiser. But a black hole changes things, due to the presence of the event horizon. When a virtual particle/antiparticle pair pops into existence very close to the horizon, one of the particles can fall in, and obviously has no choice but to continue on to the singularity. The other partner, meanwhile, is now able to escape to infinity. The event horizon has served to rip apart the virtual particle, gobbling up one of the particles. The one that escapes is part of the Hawking radiation.
Carroll then goes on to explain the basic problem resulting from Hawking's discovery:
We can imagine a book falling through the horizon, all the way to the singularity (or whatever should replace the singularity in a better theory of quantum gravity), taking the information contained on its page along with it. Meanwhile, the radiation that purportedly carries away the same information has already left the black hole. How can this information be in two places at once? As far as Hawking's calculation is concerned, the outgoing radiation is the same for every kind of black hole, no matter what went into making it. At face value, it would appear that the information is simply destroyed; it would be as if, in our earlier checkerboard examples, there was a sort of blob that randomly spit out gray and white squares without any consideration for the prior state.
This puzzles is known as the "black hole information-loss paradox". Because direct experimental information about quantum gravity is hard to come by, thinking about ways to resolve this paradox has been a popular pastime among theoretical physicists over the past few decades. It has been a real controversy within the physics community, with different people coming down on different sides of the debate. Very roughly speaking, physicists who come from a background in general relativity (including Stephen Hawking) have tended to believe that information really is lost, and that black hole evaporation represents a breakdown of the conventional rules of quantum mechanics; meanwhile, those from a background in particle physics and quantum field theory have tended to believe that a better understanding would show that the information was somehow preserved.
Hawking made a bet with John Preskill about whether information is permanently lost or can leak out from a black hole, but in 2004 he conceded defeat and admitted that the information probably is preserved. I believe Hawking is now trying to reconcile quantum mechanics and general relativity as it pertains to Hawking radiation, because general relativity suggests that we should not have the capacity to reconstruct the information that fell into the black hole. That's why Hawking believed in the first place that the information was lost.
EDIT: By saying that information is lost within a black hole, Carroll means that we can measure the mass, spin, and charge of a particle, but nothing more. All previous "information" about the particle is destroyed.
Robot Pants
Member
Scanners_headexplode.gif
Opinionatedfish
Member
I think the only way to settle all of this is to find the nearest Black Hole and launch Stephen Hawking into it.
It's time.
It's time.
NobleGundam
Banned
Yeah, I know. How did the headline go from "Hawking says event horizons don't exist" to "Hawking says black holes don't exist?"
Now, black holes are actually "grey."
http://www.nbcnews.com/science/step...gain-black-holes-are-actually-gray-2D12001605
Phil Plait? Michio Kaku? Neil Degrasse Tyson? Where are you? We needs you.
Fenderputty
Banned
Depends on what you mean by "near". While tidal forces from a black hole can rip practically anything to shreds, they are still just massive objects governed by gravitational laws, so objects in their proximity (in terms of galactic or stellar scales) just orbit them accordingly (albeit in a relatively spectacular fashion). This can theoretically be extended to space within the Schwarschild radius. The true mystery is what happens at the singularity at the black hole's centre.
D
Deleted member 231381
Unconfirmed Member
Thanks, mgo, that was really interesting. In a manner a total layman would understand (this may not be possible 
), what are the implications if this is true for physics?
), what are the implications if this is true for physics?schroddycat
Member
Thanks, mgo, that was really interesting. In a manner a total layman would understand (this may not be possible
I'm also interested to Faora & the rest of the kryptonian... they got sucked into black hole and then what?
Chuckie
Member
Crazy awesome.
Sapphire Dreams
Member
Okay, now he is saying that black holes are gray.
http://m.nbcnews.com/science/stephe...gain-black-holes-are-actually-gray-2D12001605
http://m.nbcnews.com/science/stephe...gain-black-holes-are-actually-gray-2D12001605
BumblebeeCody
Member
Mgoblue201
Won't stop picking the right nation
I don't have any particular insight into physics either, so this isn't beyond anyone's capacity to understand. Everything I know about physics comes from books and articles I've read. Nature is a much better source to discuss the implications of Hawking's theory:Thanks, mgo, that was really interesting. In a manner a total layman would understand (this may not be possible
Unlike the event horizon, the apparent horizon can eventually dissolve. Page notes that Hawking is opening the door to a scenario so extreme “that anything in principle can get out of a black hole”. Although Hawking does not specify in his paper exactly how an apparent horizon would disappear, Page speculates that when it has shrunk to a certain size, at which the effects of both quantum mechanics and gravity combine, it is plausible that it could vanish. At that point, whatever was once trapped within the black hole would be released (although not in good shape).
If Hawking is correct, there could even be no singularity at the core of the black hole. Instead, matter would be only temporarily held behind the apparent horizon, which would gradually move inward owing to the pull of the black hole, but would never quite crunch down to the centre. Information about this matter would not be destroyed, but would be highly scrambled so that, as it is released through Hawking radiation, it would be in a vastly different form, making it almost impossible to work out what the swallowed objects once were.
“It would be worse than trying to reconstruct a book that you burned from its ashes,” says Page. In his paper, Hawking compares it to trying to forecast the weather ahead of time: in theory it is possible, but in practice it is too difficult to do with much accuracy.
The reason why it's theoretically (though not practically) possible to reconstruct the past is because information about matter is conserved. Particles "evolve" into a very particular arrangement or state over time, and as Carroll says, "knowledge of the future state is sufficient to figure out what the appropriate state in the past must have been." In other words, if you throw a book into a fire, and somehow knew the complete microscopic state of the universe after it burned, then you could "theoretically run the clock backward" and reconstruct the book, because the particles contain "information" about their own prior state. This has interesting implications. It means, in a sense, that "there's no difference between reconstructing the past and predicting the future."
The paradox results, as I said before, from the contradiction between quantum physics, which suggests that information can't be destroyed, and general relativity, which suggests that nothing can escape from an event horizon and the information coming out is random, so that you could never reconstruct its prior state. Hawking resolves the paradox by removing the event horizon completely. His idea is that the "quantum effects around the black hole cause space-time to fluctuate too wildly for a sharp boundary surface to exist." Objects could therefore technically escape from a black hole, albeit in a much different state, without violating general relativity. When things fall into the chaotic millieu, they enter a state of extreme disarray from which they are eventually released.
That's my understanding, anyway; any physicists should feel free to correct me. It should be noted that Hawking's results are very preliminary. I don't even think it's been peer reviewed yet.
This is how I understood the singularity. It's a mathematical point, the limit reached when using the equations on that infinity, but it's just hypothetical. It may just show that the equations are inaccurate to describe what's happening in such extreme conditions, just like Newton's laws are inaccurate when reaching near the speed of light.
I once heard the hypothesis that, at a sufficiently high density, gravity would be able to negate the nuclear force, to pull together nucleons and negate the space between them. With this idea, the singularity would be a bunch of particles melted together, in a tiny fraction of space but generating a huge gravity field. Kind of like the density of stars allows for nuclear fusion, density of a singularity would allow for "quark fusion" or something like that.
*I'm no physicist, obviously.
Ether_Snake
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Two things I don't get:
1- How cam radiation can leave the blackhole? Wouldn't it be attracted back into it too?
2- Why is it that the giant mega star (I forget the name, but it's so huge it makes our sun look microscopic) can be so massive and yet not collapsed into a blackhole? You need even more mass than that?
1- How cam radiation can leave the blackhole? Wouldn't it be attracted back into it too?
2- Why is it that the giant mega star (I forget the name, but it's so huge it makes our sun look microscopic) can be so massive and yet not collapsed into a blackhole? You need even more mass than that?
As I understood it the virtual pair is formed right at the edge of the event horizon, one particle in, the other out, allowing it to escape.
I learned today about radiation pressure. Basically as long as there is fusion, gravity is opposed to this pressure and the star is kept stable. Once fusion can't be done anymore because of lack of hydrogen to use, the star collapses and make other objects, potentially a black hole. So supposedly you don't need that much mass, but it needs to be inert.
All those informations up there about what would happen if we fell in a black hole's event horizon are interesting, but not satisfying.
If I understand correctly, after we cross an event horizon all directions point to the singularity. But logic tells me that if it's the case, all movements beyond that point are impossible, should it be brain activity or blood flow.
So basically everything passing through an event horizon would just be frozen until spaghettification happens, and thus not compatible with any form of life. It would also mean that the insane gravity would probably kill us long before we even reach the event horizon, even in the case of a super massive black hole, as our blood flow would have stopped since it would be too weak to defy gravity.
So if I understand things correctly, event horizon or not, it doesn't really matter. No one would make it near a black hole alive.
If I understand correctly, after we cross an event horizon all directions point to the singularity. But logic tells me that if it's the case, all movements beyond that point are impossible, should it be brain activity or blood flow.
So basically everything passing through an event horizon would just be frozen until spaghettification happens, and thus not compatible with any form of life. It would also mean that the insane gravity would probably kill us long before we even reach the event horizon, even in the case of a super massive black hole, as our blood flow would have stopped since it would be too weak to defy gravity.
So if I understand things correctly, event horizon or not, it doesn't really matter. No one would make it near a black hole alive.
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