Hawkings changes black hole theory.

MrSelf · Post by **MrSelf** » Sat Jul 17, 2004 10:03 pm

Stephen Hawking says he was wrong about a key argument he put forward 30 years ago on the behaviour of black holes.
The world-famous physicist addresses an international conference on Wednesday to revise his claim that black holes destroy everything that falls into them

He will tell the Dublin meeting that he now believes black holes may after all allow information to get out. His new findings could even help solve the "black hole information paradox", a crucial puzzle of modern physics.

Professor Hawking has not yet revealed the detailed maths behind his new ideas, but some points have leaked out from a seminar he gave at the University of Cambridge.

Gary Gibbons, another physicist at Cambridge who attended the seminar, said Hawking's newly defined black holes did not have a well-delineated "event horizon" that hid everything in them from the outside world. "It's possible that what he presented in the seminar is a solution," Professor Gibbons told New Scientist magazine. "But I think you have to say the jury is still out."

Little and large

Professor Hawking's own work was responsible for generating the black hole information paradox.

In 1976, he calculated that once a black hole forms, it radiates energy and starts losing mass. This radiation gives no information about matter inside the black hole and once the hole disappears, all the information goes with it. "It used to be thought that once something had fallen into a black hole it was gone and lost forever and the only information that remained was its mass and spin," the Lucasian Professor of Mathematics at Cambridge told the BBC.

"But some time ago I discovered that black holes are not that black after all. They give off what has been called 'Hawking radiation'. Because of this emission black holes will lose mass and eventually evaporate completely. "The Hawking radiation seemed to be random and featureless so it appeared that all information about what fell into a black hole was lost."

But this runs contrary to the laws of quantum physics, which describe the behaviour of the Universe at the smallest scales. These dictate that information can never be completely lost.

"If information can be lost it has important practical and philosophical consequences," he added. "We could never be certain of the past or predict the future precisely. A lot of people therefore wanted to believe that information could escape from a black hole but they didn't know how it could get out."

Losing bet

For years, the physicist argued that the extreme gravitational fields of black holes somehow overturned the quantum laws. Now, he has dropped this idea.

Professor Hawking's new black holes never completely destroy everything that falls in. Instead, they continue to emit radiation for extended periods, and eventually open up to reveal the information within them.

"I have been thinking about this problem for 30 years, but I now have an answer to it," he explained. "The black hole only appears to form but later opens up and releases information about what fell in, so we can be sure of the past and we can predict the future."

The U-turn could cost Professor Hawking an encyclopaedia. He and theoretical physicist Kip Thorne, of the California Institute of Technology, made a bet on the subject with an opponent of the idea, John Preskill, also of Caltech. Hawking and Thorne are expected to present Preskill with an encyclopaedia of his choice.

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fcbayer · Post by **fcbayer** » Sat Jul 24, 2004 7:36 pm

i read about this topic a couple days ago it what quite an interesting topic.
it was Hawking's Theoretical reversal:

Hawking, 62, said he no longer believes a 1980s theory that black holes might offer passage into another universe, a rival explanation for identifying where matter and energy go when consumed by a black hole. Hawking now sides with particle physicists who have long insisted that any matter swallowed by a black hole can’t just disappear but must eventually generate a specific output. “If you jump into a black hole, your mass energy will be returned to our universe, but in a mangled form, which contains the information about what you were like, but in an unrecognizable state.”
Not long ago, Hawking was just as certain that black holes destroyed whatever they took in.
“information swallowed by a black hole is forever hidden from the outside universe and can never be revealed, even as the black hole evaporates and completely disappears.”
John Preskill, also a Caltech professor, insisted that information on a black hole’s consumption “must and will be found in the correct theory of quantum gravity.”

but i consider this article more realistic than that stuff about black holes being "holes to other worlds".

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Chyse · Post by **Chyse** » Sun Jul 25, 2004 3:55 pm

a black hole is really just a really really really dense planet that's gravity is to strong that light can not escape. like if you shoot a bullet in the air, it will fall. because the force of gravity is too great. same with light in a black hole/planet.

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Red Squirrel · Post by **Red Squirrel** » Sun Jul 25, 2004 5:58 pm

Simply put, the gravitational speed is the same as the speed of light, which is why even light can't escape. But something faster then light could, but it's also been theorized that it's impossible for anything to go faster then light, thus, making it so nothing can escape.

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Chyse · Post by **Chyse** » Sun Jul 25, 2004 8:16 pm

Red Squirrel wrote: Simply put, the gravitational speed is the same as the speed of light, which is why even light can't escape. But something faster then light could, but it's also been theorized that it's impossible for anything to go faster then light, thus, making it so nothing can escape.

it wasn't E=mc2 if that's what your thinking. because i talked to thes physics professor about it and he said that isnt the theory.

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Red Squirrel · Post by **Red Squirrel** » Sun Jul 25, 2004 8:33 pm

I just can't think of the proper term for it since it's not gravity speed, since the speed of gravity is not really known and it's not 9.9m/s/s since that's gravity acceleration and not speed, and changes on differnet planets. But if I can find the proper term it would help.

Basically each planet has a speed at which you throw an object in the air in which it won't come back, and for a black hole, that speed is the speed of light, while earth, it's a few thousand km per hour, or something like that. (well whatever speed a rocket is lauched at, I assume)

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Chyse · Post by **Chyse** » Sun Jul 25, 2004 8:43 pm

Red Squirrel wrote: I just can't think of the proper term for it since it's not gravity speed, since the speed of gravity is not really known and it's not 9.9m/s/s since that's gravity acceleration and not speed, and changes on differnet planets. But if I can find the proper term it would help. Basically each planet has a speed at which you throw an object in the air in which it won't come back, and for a black hole, that speed is the speed of light, while earth, it's a few thousand km per hour, or something like that. (well whatever speed a rocket is lauched at, I assume)

yeah, it starts with a "c". i know that. it's like colper's law or something like that.

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MrSelf · Post by **MrSelf** » Mon Jul 26, 2004 6:18 pm

Red Squirrel wrote: Simply put, the gravitational speed is the same as the speed of light, which is why even light can't escape.

Where gravitational force is equal to or greater than.

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Red Squirrel · Post by **Red Squirrel** » Mon Jul 26, 2004 6:31 pm

Yeah it can be bigger, that's if it's possible for stuff to go faster then light, which has not yet been proven, I don't think. I think it is possible, it's just that there's nothing that fast, that we know of, but gravity could be faster.

I need to start working on that rail gun of mine. Split the earth in half and use the North and South pole as the two rails, and build a space ship as the projectile.

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mimic · Post by **mimic** » Mon Jul 26, 2004 9:27 pm

Simply put, the gravitational speed is the same as the speed of light, which is why even light can't escape.

Actually, the gravitational pull is stronger since light can't escape?

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Red Squirrel · Post by **Red Squirrel** » Tue Jul 27, 2004 9:17 pm

Hmm makes sense since if it was the same, light would be able to pass by and not really be pulled in, it would probably curve, but would make it in the hole, but all this depends on what angle it's going at. 45degree and more would probably make it out while anything more direct would not.

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mimic · Post by **mimic** » Tue Jul 27, 2004 10:22 pm

I don't think angle of passage would matter since we're talking about the gravitational pull and mainly, the escape velocity, in this case. The escape velocity from a black hole is greater than the speed of light, so it would be pulled in regardless of flight angle.

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Chyse · Post by **Chyse** » Thu Jul 29, 2004 10:14 am

mimic wrote:
Simply put, the gravitational speed is the same as the speed of light, which is why even light can't escape.
Actually, the gravitational pull is stronger since light can't escape?

that's imposible apparently. because then when something fell into it. it would go faster that the speed of light. which is proven impossible.

edit: never mind i didnt read the past posts. sorry.

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Jon · Post by **Jon** » Thu Jul 29, 2004 3:03 pm

Erm, what is all of this 'gravitational speed' nonsense? Gravity is not a tangible part of our universe, it doesn't 'travel' anywhere and has no velocity. It simply curves space, and in the case of a black hole, since recalling that light can only travel at c no matter how you observe it, space is bent to the extent it curves straight back into it's own mass... the light continues to travel away in a straight line... just along a curved part of space- it can't escape for that reason.

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MrSelf · Post by **MrSelf** » Thu Jul 29, 2004 3:25 pm

I'm sure they mean force.

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Jon · Post by **Jon** » Thu Jul 29, 2004 4:11 pm

Indeed. Still, the light is only following a path that has been bent by mass, it's not being 'pulled' anywhere, gravity can't directly affect a massless object.

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Red Squirrel · Post by **Red Squirrel** » Fri Jul 30, 2004 1:32 pm

Yeah we mean force, and by speed we mean the speed an object has to be going at in order to avoid the force. Ex: how fast you have to launch a rocket to get it in space.

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MrSelf · Post by **MrSelf** » Fri Jul 30, 2004 3:39 pm

Red Squirrel wrote: Yeah we mean force, and by speed we mean the speed an object has to be going at in order to avoid the force. Ex: how fast you have to launch a rocket to get it in space.

That's completely dependent on the mass/density of the object.

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mimic · Post by **mimic** » Fri Jul 30, 2004 9:23 pm

Yea, I meant escape velocity. A black hole's escape velocity is greater than anything we know, including light, so nothing can escape.

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Dumb Genius · Post by **Dumb Genius** » Sat Jul 31, 2004 1:43 am

mimic wrote: Yea, I meant escape velocity. A black hole's escape velocity is greater than anything we know, including light, so nothing can escape.

yeah apparently it was the case before his new theory. now it seems that some "radiations" are emmited. but the article does not really explain anything about it... worm holes should be forgotten, ok... but it says "radiation" but i wonder of what of nature. this article is not satisfying at all. do you have the link where you found that?

i consider this article more realistic than that stuff about black holes being "holes to other worlds".

how can you say it's more realistic? here you're just guessing. even the greatest scientits can't answer to that.

it wasn't E=mc2 if that's what your thinking. because i talked to thes physics professor about it and he said that isnt the theory.

stop thinking that this formula solves every problem of the universe or that you can not understand it. it's used eveyday in chemistry, nuclear physics, electro-magnetism... for simple calculations, even college student use it. it's just an energy formula...

i think some of you have a lot of misconceptions. and it's normal i guess. i dont even know how they possibly curve the spacetime and why light follows this curvature since photons have no mass. it's too advanced for us.
the ones who gave their opinion should not simply because you dont have sufficient knowledge and no evidence or arguments at all.

this subject is fascinating and it opens our minds but that's all.

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MrSelf · Post by **MrSelf** » Sat Jul 31, 2004 1:51 am

Dumb Genius wrote:
mimic wrote: Yea, I meant escape velocity. A black hole's escape velocity is greater than anything we know, including light, so nothing can escape.

yeah apparently it was the case before his new theory. now it seems that some "radiations" are emmited. but the article does not really explain anything about it... worm holes should be forgotten, ok... but it says "radiation" but i wonder of what of nature. this article is not satisfying at all. do you have the link where you found that?

i consider this article more realistic than that stuff about black holes being "holes to other worlds".
how can you say it's more realistic? here you're just guessing. even the greatest scientits can't answer to that.

it wasn't E=mc2 if that's what your thinking. because i talked to thes physics professor about it and he said that isnt the theory.
stop thinking that this formula solves every problem of the universe or that you can not understand it. it's used eveyday in chemistry, nuclear physics, electro-magnetism... for simple calculations, even college student use it. it's just an energy formula...

i think some of you have a lot of misconceptions. and it's normal i guess. i dont even know how they possibly curve the spacetime and why light follows this curvature since photons have no mass. it's too advanced for us.
the ones who gave their opinion should not simply because you dont have sufficient knowledge and no evidence or arguments at all.

this subject is fascinating and it opens our minds but that's all.

Yeah, there are a lot of post that take unsure theories and make them into law, and I honestly think we will revamp our theory on gravity and many other universal theories completely in the next 10 years; much of what we think we know will shift slightly.

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MrSelf · Post by **MrSelf** » Sat Jul 31, 2004 1:52 am

and I don't have the link but it was on the bbc site.

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mimic · Post by **mimic** » Sat Jul 31, 2004 2:40 am

the ones who gave their opinion should not simply because you dont have sufficient knowledge and no evidence or arguments at all.

That's a piss poor attitude to have. I got it by reading books over time, just like 99% of the world that has an opinion. You don't have any knowledge on this anymore than we do and I wouldn't say something like that just because I didn't agree with you. Of course I don't have first hand knowledge, I'm not in space and going through black holes anymore than you are. It's by debating that someone can learn, if given the knowledge in the correct fashion. If I'm wrong, that's fine, tell me why but I don't think it's necessary to come along and say we shouldn't give our opinions or don't have evidence or arguments just because you think we are.

this subject is fascinating and it opens our minds but that's all.

I agree and exactly why we're all talking about it. I don't see any harm in that? This is AF, not NASA, and I don't think anyone's taking it too seriously.

I honestly think we will revamp our theory on gravity and many other universal theories completely in the next 10 years; much of what we think we know will shift slightly.

I agree Mr Self. I also think it may always be everchanging as we learn more and some theroies are debunked and others come to fruition.

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Dumb Genius · Post by **Dumb Genius** » Sat Jul 31, 2004 2:44 am

mimic wrote:
the ones who gave their opinion should not simply because you dont have sufficient knowledge and no evidence or arguments at all.
That's a piss poor attitude to have. I got it by reading books over time, just like 99% of the world that has an opinion. You don't have any knowledge on this anymore than we do and I wouldn't say something like that just because I didn't agree with you. Of course I don't have first hand knowledge, I'm not in space and going through black holes anymore than you are. It's by debating that someone can learn, if given the knowledge in the correct fashion. If I'm wrong, that's fine, tell me why but I don't think it's necessary to come along and say we shouldn't give our opinions or don't have evidence or arguments just because you think we are.

i didnt perceive that as a debate but as affirmations that's why i'm telling that. i dont want to offense anyone here. and i love you all

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OLKMED · Post by **OLKMED** » Sat Jul 31, 2004 2:45 am

I don't understand why anyone would think that it is impossible to go faster than the speed of light. We're nowhere near that speed in any of our travels, and 200 years ago we probably didn't think we could even break the sound barrier (If we knew what that was

)
I think that science could go on improving and proving wrong the theories we all have for years and years.

as my quote says

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