How the Black Hole Firewall Paradox Was Resolved 118
Stephen Hawking's recent comments about the nature of black holes have bred uncertainty about physics concepts that were relatively well understood. This article from astrophysicist Ethan Siegel explains that yes, black holes still exist, and how a group of three academic papers answered the black hole 'firewall' paradox. Quoting:
"... And so what these three papers, in tandem, have done, is demonstrate that there is no firewall and that the resolution to the firewall paradox is that the first assumption, that Hawking radiation is in a pure state, is the one that's flawed. You won't read about this in the popular write-ups because it doesn't have a catchy headline, it's complex, and it's not work by someone that's already very famous for other work. But it's right. Hawking radiation is not in a pure state, and without that pure state, there's no firewall, and no paradox. There is still an incredible amount to learn and understand about black holes, event horizons, and the behavior of quantum systems in strongly curved spacetime, to be sure, and there's lots of very interesting research ahead. These findings arguably raise more questions than they answer, although at least we know that black holes won't fry you when you fall in; it will still be death by spaghettification, not by incineration!"
Begs the question (Score:5, Insightful)
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Why do you think His Noodiliness is the Flying Spaghetti Monster and not the Stationary Spaghetti Monster?
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I sense a schism forming. Flying Orthodox vs. Liberal Stationary. Go!
Re:Begs the question (Score:5, Funny)
Black holes are some of the most dramatic events the cosmos: As round and powerful as his meaty balls, and within spaghettified as his noodly appendages.
Ramen, indeed. The proof of His divine influence is writ in all scales throughout the heavenly quantum sauce.
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"it will still be death by spaghettification, not by incineration!"
Thats a relief.
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No it doesn't beg the question, it raises it.
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"Raising the question" and "assuming the conclusion" are both valid interpretations of the phrase "begging the question". English is context-sensitive, so the same expression can mean multiple different things. And nothing you do will change that.
At least we don't roast. (Score:4, Insightful)
I always thought... (Score:1)
I always thought Black Holes were just one-way wormholes into another dimension of space-time. What gets sucked in from our universe is spat out in some other dimension, and these other dimensions contained the "missing" matter and energy supposed by "Dark Matter"/"Dark Energy". Basically, our universe lives on one side of a sheet of paper, a black hole is just pulling the stuff through to the other side of the sheet that we can't see.
Re:I always thought... (Score:5, Informative)
The problem with that is that black holes need the mass they suck in to exist.
The mass cannot both be in the black hole and shot out the other side into a new universe.
So unless you can come up with a theory that has black holes creating mass out of nothing, that is simply impossible.
Re: I always thought... (Score:1)
Re: I always thought... (Score:4, Informative)
There is some debate exactly what happens when you get enough mass together to tie space-time into knots. The most important part of a black hole is really the event horizon, which is the point X distance from the center of mass of a black hole where the gravitational pull is so strong that nothing can escape. The original idea was that is was a very static place, a perfect circle.
There is a bunch of different problems with this. Because in this universe we have the idea that mass, energy, and information cannot be lost. Something cannot just go into a black box and all knowledge of it is lost, because then information would then of been lost.
Stephen hawking's has just come forward with the idea that it is a far more stormy area with fluctuating gravity. Which would allow this information to escape. Previously the idea was Hawking radiation, which would allow things to escape from the black whole even without fluctuation gravity.
One of the problems of with the horizon, that someone just proposed, was that it would be so tumultuous at the edge that everything would be burned beyond recognition,. This article is about how stuff entering a BH would NOT in fact be burned beyond recognition.
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where the gravitational pull is so strong that nothing can escape.
I always wondered about this. Isn't it just a basic calculation showing the point where escape velocity exceeds the speed of light? Meaning that ballistically nothing can escape on it's own, but if you had a "space elevator" (with super-strong cables not defined here) you could raise and lower things into a black hole (or planet Earth) at whatever speed you wanted. So why not lower in a camera and take a look? And if the super-strong cable also does Ethernet, you wouldn't even have to raise it back, unless
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Since electrons have mass they're susceptible to gravity. So no, you couldn't get any kind of signal out of a black hole.
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Yes, but no. They would be susceptible to the gravity, and could not be launched out of a black hole. But electricity works on more of a pump like system. And like he said, you might be able to theoretically pull the electrons out of the black hole.
Yes you could not easily transmit back, and a battery inside of a black hole simply would not work. But if you have a huge electron pump outside of the black hole and a cable that goes in and one that comes back, you might be able to push the electrons through an
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I am no expert, but I think you are right theoretically. Practically, I think it would simply be impossible to construct anything that that would survive.
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If we're already talking about an "infinitely strong material" suspending the camera inside the event horizon, wouldn't that mean that the supporting material would have to be accelerating (~"holding up") the camera away from (up/out of) the black hole at the speed of light already? I would think that would make raising the camera--or getting any information back out of it--impossible, as you'd need to accelerate the camera/information at c+x to get it back.
Re: I always thought... (Score:1)
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wisnoskij blathered:
The problem with that is that black holes need the mass they suck in to exist.
The mass cannot both be in the black hole and shot out the other side into a new universe.
So unless you can come up with a theory that has black holes creating mass out of nothing, that is simply impossible.
Sorry, but you can't prove that contention. Period.
In the Standard Model, black holes are singularities. BY DEFINITION, the laws of physics as we observe and understand them break down in singularities. The SM can't explain what is going on inside a black hole, AND NEITHER CAN YOU.
Unless you have a doctorate in cosmology or astrophysics, you doubtless are profoundly unqualified even to have an OPINION on the topic ... so, kindly STFU.
Thank you.
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(I do have a doctorate in cosmology and I've a contention with what you've said: a black hole is not a singularity, whether by definition or otherwise. A "black hole" is simply a region in vacuum shrouded by an event horizon, and this situation occurs when a body is compressed enough that it lies entirely within its event horizon. In classical GR there are a few ways to get to this situation, with perhaps the most common being the collapse of a supermassive star. In classical GR there is also a singularity
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An Anonymous Coward commented:
(I do have a doctorate in cosmology and I've a contention with what you've said: a black hole is not a singularity, whether by definition or otherwise. A "black hole" is simply a region in vacuum shrouded by an event horizon, and this situation occurs when a body is compressed enough that it lies entirely within its event horizon. In classical GR there are a few ways to get to this situation, with perhaps the most common being the collapse of a supermassive star. In classical GR there is also a singularity at the centre of the black hole, but a quantum theory of gravity would be expected to smear this out. What this does not imply is that a quantum theory of gravity would destroy the concept of a black hole entirely -- instead it seems very likely that in a quantum theory of gravity we would retain an event horizon, merely a somewhat "smeared" and non-absolute form of one (a distinction that would seem heartlessly academic to any poor sod falling into a hole). Hawking's conjecture, which is eerily similar to an equally unproven conjecture he advanced a few years back to "prove" that the information paradox was solved, is that ultimately there are no "black holes" because they are not an infinite state -- eventually they will dissipate, which immediately implies that their "event horizons" are actually apparent horizons. So far as this goes, it strikes me as eminently non-controversial.
Anyway, the concept of a singularity and a black hole are therefore rather distinct.)
I sit corrected.
However, I'd like to point out that nothing in your analysis validates wisnoskij's contention that the mass of a black hole has to be considered as existing entirely within this universe, therefore preventing it from acting as a "wormhole" to another one. As I understand it, whether the event horizon is actually a hard boundary or a more diffuse one, we don't currently have a solid cosmological model of what's "on the other side" of that boun
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"However, I'd like to point out that nothing in your analysis validates wisnoskij's contention that the mass of a black hole has to be considered as existing entirely within this universe, therefore preventing it from acting as a "wormhole" to another one."
A fair comment - I put my entire reply in parantheses because it was meant to pick at one of your statements, rather than the entire post, something I should have made a lot clearer.
With the wormhole thing, the idea basically comes from a maximal extensio
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Seems a bit silly to say "this is not a black hole"...we're basically saying that RBG 010101 is not dark enough to be considered black because 000000 is the "real" black, aren't we?
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In the Standard Model, black holes are singularities.
Really? I always that the presence of the singularity is what causes the black hole to be, but they're not actually one and the same.
Comological Doctor AC agrees here [slashdot.org].
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Indeed, even without quantum gravity, both are not the same, because GR allows singularities which are not "protected" by horizons (so-called naked singularities). Since they have no horizon, they would not be black holes. AFAIK it is however conjectured that naked singularities cannot actually form (what is AFAIR definitely proved is that you cannot turn a black hole into a naked singularity).
I've once tried to calculate if an electron were a black hole, how large that black hole would be, and unless I've
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AFAIK it is however conjectured that naked singularities cannot actually form (what is AFAIR definitely proved is that you cannot turn a black hole into a naked singularity).
There are singularities all over physics, even in something as simple as the velocity field of a classical vortex (v ~ 1/r). The world doesn't go all goofy at them-- the universe tends to take care of them in relatively convenient and pedestrian ways, like by sending the density to zero where the velocity goes to infinity. It's all fun to be a theorist talking about naked singularities (probably as close to naked anything as many of them get...) but if someone figures out a way to actually observe what's g
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Except that in GR, the density goes to infinity at the singularity. However it is indeed expected that in nature those singularities don't actually form — however the reason is not as mundane as a certain quantity going to zero; rather the reason being that in that region quantum gravitation should kick in, and thus the classical equations of General Relativity are simply no longer applicable. Somewhat similar to how quantum electrodynamics solves the problem of the field singularity of classical poin
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The universe probably finds some convenient way to force things to reasonable values. The density going to zero was just an example of a particular case. And quantum gravitation? Show me before you tell me where it kicks in. The universe is going to do what it's going to do, and it's generally well behaved, despite what happens where theories break down.
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wonkey_monkey pointed out:
I maintained:
In the Standard Model, black holes are singularities.
To which wonkey_monkey responded:
Really? I always that the presence of the singularity is what causes the black hole to be, but they're not actually one and the same.
Comological Doctor AC agrees here [slashdot.org].
Thanks for calling my attention to his post.
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To be more detailed, the black hole is creating (in this fanciful theory) a new universe that is the size of the black hole from the outside but that is the size of a universe from the inside.
So what you're saying is it's larger on the inside? [wikipedia.org]
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The problem with that is that black holes need the mass they suck in to exist.
The mass cannot both be in the black hole and shot out the other side into a new universe.
So unless you can come up with a theory that has black holes creating mass out of nothing, that is simply impossible.
It's not shot out another side into a new universe. It simply falls in and it's there, in our universe. Hawking says that this reaction (Stuff getting compressed into a really small space) causes radiation to be emitted. The radiation part is observable, how they came up with the idea in the first place.
The thing I don't agree with is their theory that times slows down. In fact if you believe them, towards the very center of this black hole, time stops while we remain ticking away. I always thought this
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I think you are confused.
I do not think that compression is what causes the radiation. The way I understood it, it is sort of just something that happens everywhere, but is noticeable at the black hole because it is the only thing there that escapes.
And time does not slow down because of some BH property, and it is not the center that this occurs at. We know beyond doubt both theoretically and practically that time, or the perception of it, is linked to velocity. Everything, at the event horizon is going th
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I think you are confused.
I do not think that compression is what causes the radiation. The way I understood it, it is sort of just something that happens everywhere, but is noticeable at the black hole because it is the only thing there that escapes.
And time does not slow down because of some BH property, and it is not the center that this occurs at. We know beyond doubt both theoretically and practically that time, or the perception of it, is linked to velocity. Everything, at the event horizon is going the speed of light. Which means that time stops, based on a certain relative frame of reference.
Might be confused. I haven't looked at this stuff for 30 years. However looking at the wiki I think I'm still on track. It may not be the compression per se, it's whatever is going on at that point. Of course we don't know what that is. I remember a prof saying "weird stuff is going on in there." Weird indeed, I pointed out if time stopped as they said it did, then how could things compress/react/emit stuff? Of course we didn't get a very good answer. There is a center, there always is. That center ma
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I wonder if this whole "time stopping at the center of a black hole" bit is analogous to Bose-Einstein condensates somehow...</muse>
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Thank you, Captain Literal. I meant time almost stopping in a black hole, as compared to the energy level of each particle in BEC reaching the minimum. Both of them are things that can't happen in anything approaching "normal" circumstances.
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The problem with that is that black holes need the mass they suck in to exist.
The mass cannot both be in the black hole and shot out the other side into a new universe.
So unless you can come up with a theory that has black holes creating mass out of nothing, that is simply impossible.
You make it seem so black and white, but you're logic is flawed:
Black holes just need a minimum (critical) amount of mass to exist. Anything over that limit is mass that can be lost.
Take binary stars as an analogy. They also need mass to exist, yet trade mass back and forth all the time.
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Except that black holes come in all different masses. You do not get a super massive black holes that is heavier than 1000 of the biggest stars that ever existed, without incoming mass being added it its own.
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Disney really fucked up another generation (Score:2)
Re:I always thought... (Score:5, Informative)
No it isn't. A cosmological model is a foliation of maximally-symmetric spacelike hypersurfaces. A black hole is not maximally-symmetric. A black hole is a non-evolving system -- it possesses at least one timelike Killing vector -- and a cosmological system is the exact opposite, an evolving system that has no timelike Killing vector. The only real similarity is that a black hole (as you're doubtless meaning it; a Schwarzschild solution) is spherically symmetric, and the spacelike slices in a cosmological spacetime are also spherically symmetric. But so is flat Minkowski space, and so are Tolman-Bondi spaces.
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Re: I always thought... (Score:2)
Whew! (Score:3)
... at least we know that black holes won't fry you when you fall in; it will still be death by spaghettification, not by incineration!
Well, that's a load off my mind. I'll be sleeping much better - thanks.
Although, now I have a hankering for some fried spaghetti.
Comment removed (Score:5, Insightful)
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No, this is all still highly theoretical ....
Tell that to the experimentalist who was just torn apart by spaghettification (he was planning to go out in a blaze of glory)....
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ALL science is "still a theory". Remember that the scientific method isn't EVER about stating absolutes.
Examples: the theory of gravity, the shape of the Earth, kinetics and dynamics (which we know are more complicated than the Newtonian models we still teach but we know when they become wrong so it isn't a problem).
This is the problem with pitching science to a mainstream audience: they think it is a religion when it actually resembles that in no way.
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However, this is an untested theory. That is, up to now we have no experiment confirming it. Indeed, there's not even experimental confirmation of Hawking radiation (the black holes we can observe are too large to emit any non-negligible Hawking radiation).
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you cannot state that this hypothesis is absolutely, definitely correct.
That's your theory.
Piffle (Score:2)
You fall into a black hole and you will heated up from friction to the point that you become atomized. The idea that wouldn't be incinerated is absurd when the brightest and hottest objects in the universe are quasars caused by material being incinerated from friction. Now whether you are incinerated first or spaghettified first or killed by radiation is a different story. One way or another though you will be incinerated.
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most black holes are not quasars (supermassive black holes at center of galaxy with large amounts of matter in accretion disk), and there can be black holes not surrounded by infalling matter
Solution (Score:5, Funny)
But what if you reconfigure the main deflector to emit a tachyon pulse
Engineering response... (Score:2)
Oh those science officers think their so smart, and command always listens to them! That's like saying can you reconfigure this combustion engine to run on fairy dust and play the harpsichord? So we will do what we always do, fix it how it should be fixed, and let them live in their dream world. Just don't forget to pad your estimate for about double, as they will likely only actually give you half the time to do it in if your lucky. Bastards!
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You fall into a black hole and you will heated up from friction to the point that you become atomized.
The most generous interpretation of this is that you're talking about the accretion disk. Yes if your trajectory takes you into the accretion disk (assuming there is one, there doesn't have to be) you'll be atomised. No reason you can't come in from an angle that doesn't take you into the disk though. In those instances you certainly won't be atomised; black holes are very very cold. So cold in fact that the vacuum in the universe won't be colder than any stellar-mass black hole for the very distant future.
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You need sufficient atmosphere to experience friction, don't you? And if the atmosphere is all getting sucked in with you...
Unless we're talking about some quantum definition of friction that I'm not familiar with.
(IANAS)
There is another possible black hole's firewall (Score:2)
Im not a physicist, but hear this. Imagine for a second that most of the photons that gets trapped on a black hole will certainly head towards the singularity. Now, there is a certain distance where the orbital speed is the same as the light's speed, and that is not at the core, presuming that at the core the gravity must be strong enough to stop light from going out even at the perfect escape vector. Therefore it is possible, but very unlikely, that this orbiting light around the black hole is enough to me
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Please correct me if I'm in any way wrong.
What happens if you are in any way, right?
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There is a simple proof to the contrary but the /. comment system is too small a space in which to contain it. There are many, many hours of Susskind videos on Youtube, primarily and most recently "ER=EPR|Leonard Susskind", which deal with exactly this.
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There is a place outside the event horizon when light can orbit; however, it is an unstable orbit, and no light accumulates there. So no, you won't be fried (and there's not really even a chance it could happen.)
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Even without tunnelling, you've got the finite size of the wave packet, which means that part of your photon will be inside and part will be outside that sphere. The part inside will fall into the black hole, the part outside will escape. Which means that the probability to find the photon on the sphere will quickly vanish, with the photon going into a superposition of "fallen into the black hole" and "escaped to infinity".
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I accept that the probability is non-zero, and nothing I said conflicts with that. However, there's not really any chance that it could happen.
http://lesswrong.com/lw/ml/but_theres_still_a_chance_right [lesswrong.com]
sort of (Score:1)
You are not entirely right but - there is a distance from a given black hole at which the orbital velocity is C. But this is actually OUTSIDE the event horizon and is known as the photon sphere. It will not result in a region of intense heat because any photon in that orbit is in unstable equilibrium. This means that any minor disturbance in their velocity and they will either fall into the black hole or escape to infinity.
I highly recommend the following series of lectures if you want to learn more.
http
Complementarity (Score:5, Interesting)
It all depends where you're observing from.
If you're alice, falling through the black hole horizon, you see no horizon, and no firewall. It's a harmless point of no return. In a particularly large black hole say with a horizon the size of the solar system (this would have to be a super-galactic beastie) you could potentially live out your life in there before getting crushed by tidal forces.
If you're bob on the outside, it looks like alice slows down and gets increasingly red shifted. Alice moves asymptotically towards the horizon but never quite reaches it. Just getting slower and redder. Of course the reverse is also true, if alice looked back at bob she'd see him all sped up like keystone cops.
Because the light coming to you from the regime around alice is so red shifted, you conclude that it must be incredibly high energy/frequency down where alice is (the firewall)
The funny part is, if you send photons at alice hoping to reflect them back to yourself (to see if she's alright) - the photons have to be so energetic to make the return trip that you end up vapourising alice just as the firewall would have done.
This is the impression I get from reading Leonard Susskind's stuff, broadly taken to be black hole complementarity. Neither view is objectively more 'correct' than the other. We've accepted wave/particle duality so I don't really see how we can't have two pictures of what happens in a black hole.
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"It's her movement relative to you that causes her time to slow down."
No, it's a lot more than that. There are more causes of time dilation than movement, and more causes of redshift than movement, too. What Maritz is referring to are gravitational time dilations and gravitational redshifts, which in this situation dominate those from motion.
If you bother looking at the equations, yes, as she nears the event horizon, to an external observer she'll be moving ever slower and getting ever dimmer. (Classically)
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Are you sure? Certainly an observer at rest in the same place outside the horizon (let's call him Rob) would see Bob the more blue-shifted the closer he's to the horizon. However the closer he's to the horizon, the higher Alice's speed relative to him would be when she passes him, and since that speed is away from Bob, her view of Bob would be increasingly red-shifted relative to Rob's view. My intui
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(let's call him Rob)
No no no, scientifically his name must be Carl! Did no one teach you your A B C's? ;}
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Caaaaaarl, what's a dead human doing at the edge of our black hole!?
Hawking just said there are no black holes... (Score:2)
Or rather; there are no objects that have exactly the properties, of what we have been calling black holes.
Remember the article in Nature? [nature.com] : according to Hawking's paper [arxiv.org] : Notion of an 'event horizon', from which nothing can escape, is incompatible with quantum theory, physicist claims.
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Observation might prove problematic, given that the next black hole is not exactly close to us ... we can't simply send a space probe there to measure what it experiences when falling into it.
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Hawking made a proposition. It's not a theory, it's a proposition.
His alternative explanation is a proposition.
His refutation of blackholes is not. The original concept of a blackhole is dead. Shown to be impossible/a contradiction.
The only question is, what alternative is most accurate. His suggested alternative is indeed just a proposition, but NOT the concept that there cannot be blackholes as originally described.
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Not true. Hawking has made a sequence of statements of the form "I speculate that..." leading to "This therefore suggests that...", in a two-page paper, backed up by precisely zero equations. If he wants to "show [it] to be impossible/a contradiction" he has to demonstrate this, within the context of the theories he's working in. There are three major reasons he hasn't done so:
1) He doesn't know how to
2) No-one knows how to
3) This wasn't his intention in the start anyway, since the "paper" was a transcript
What? (Score:1)
Is it me or did the summary say nothing meaningful in English? I'm scratching my head trying to figure out what he said.
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nonsense, it's the nature of the work. every famous theorectical physicist you ever heard of has produced provably false and bad models, disproved models, models in need of more refining, models they discard themselves. From the time of the Greeks to Newton to Einstein and onward.
hawking is overly famous (Score:1)
Yes he is responsible for hawking radiation but most of the things we know about black holes now are contrary to things he has previously said. His only useful contribution was in stating that black holes destroy information but it wasn't him that disproved this - it was t'hooft and susskind. And even then he was reluctant to accept defeat. Yes his contributions were great. But other physicists out there have provided much bigger contributions with significantly less recognition. I'm mildly annoyed that
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every famous theorectical physicist you ever heard of has produced provably false and bad models
Or so everyone used to believe. ;)