Here’s the article on what he’s said. Since it’s a non-scientific report I can’t really figure out what it is exactly, but it’s fundamentally new. At first, when I read it, I though “hey, this has been his position since the 70s!”, but as I kept reading I realized it wasn’t. He’s saying there’s no specific event-horizon that blocks communication with the rest of the universe? This is totally weird to me, I’d already had several theories about black-holes and what they could and could not do that were based on this lack of information-transfer from the inside to the rest of the universe. But if it’s true, it may mean a technical possibility of finding out what’s on the other side of the now weakened event-horizon.
Hobbes
[ July 17, 2004, 02:08 PM: Message edited by: Hobbes ]
Posted by Hobbes (Member # 433) on :
Here's a better article on it. And a highlight from anbother article:
quote:This "Hawking radiation" created a paradox, because the laws of quantum physics say such information can never be completely destroyed.
Hawking now says some of the information can be determined by what a black hole emits.
"A black hole only appears to form but later opens up and releases information about what fell inside," Hawking told the British Broadcasting Corp.'s Newsnight program. "So we can be sure of the past and predict the future."
Hobbes Posted by Lalo (Member # 3772) on :
This sounds interesting, but I'm going to need to read up on the quantum physics to understand what they're talking about. (Would A Brief History of Time do?) How would one make a quantum computer out of a black hole -- even if one does submit enough classical data under the proper conditions to get feedback, that can't possibly be a practical method of computation.
Or was he just pointing out a possible use, the same way I could use a spoon to cut butter?
I'd also be interested in hearing exactly what data can come free from a black hole. The articles seem unclear, at least on first glance, on the subject.
Posted by Hobbes (Member # 433) on :
Brief History will explain Hawking's old position on black holes, I highly suggest it.
The idea of doing anything with a black hole that involved getting close to it (but not getting sucked in) is always going to be theoritical.
And what he means (I think, it's hard to tell from laymen articles, but I probably couldn't understand a fully scientific article anyways) is that classical information, like number of nuetrons, or what not, will get transmitted out, but not all the information about the quantum spin of the particles will be released.
Hobbes Posted by Hobbes (Member # 433) on :
OK, so in other words, anything you peronsally would ever notice without the aid of an experimental physcist would be information that would transmit out. But be wary when physcists use that word. What they mean is that your currrent classical condition (what you look like) would impact how the information of you was thrown out of the black hole. Just like the orginal contents of a tamotoe have something to do with the output from sticking them in a blender, so don't think you can fall into a black-hole and come out with the apprioriate number appendages; you'd be realsed as Hawking Radiation (energy).
Hobbes Posted by UofUlawguy (Member # 5492) on :
Timothy Ferris' The Whole Shebang tells a fascinating story about how Hawking changed his mind about black holes. It's not the point of the book, just a small portion of it, but the whole thing is very interesting.
Posted by zgator (Member # 3833) on :
quote: The fundamental laws of quantum physics say that information is conserved, and never can be destroyed
I thought it wasn't that the info was destroyed, just that it couldn't escape.
Posted by King of Men (Member # 6684) on :
Information is not conserved in the quantum mechanics I learned - in fact, it's not even a variable. Posted by ak (Member # 90) on :
I've never liked his science books for laymen, because he just describes and doesn't explain. I prefer his articles in Scientific American where he isn't trying to dumb it down quite so far. But this definitely sounds interesting. I really want to know more about what it's about.
Posted by Bob_Scopatz (Member # 1227) on :
Is this a correct guess at what he's saying? (Note: I haven't read it yet, I'm just taking a wild ass guess first before I look it up):
1. A black hole sucks something in. We see it happen. 2. At some later time (from our frame of reference, of course) we get a glimpse AGAIN of what that something is/was. 3. The "thing" wasn't destroyed or totally absorbed like we used to think it should be. Instead, we see it as it used to be -- i.e., it somehow survived.
That means that we can view the past by looking into the future -- um, okay, I maybe skipped a step or two. But is this what he's saying?
It's interesting to think about even for people with limited knowledge of QM (like me!). I always thought that time would stop at the event horizon of a black hole. I mean the speed of light is zero, right?
But now he's saying that time goes forward but we can use it to see backward?
Or what?
I'm just confused.
<pulls out his superstring>
I think I'll just play.
Posted by King of Men (Member # 6684) on :
Oh, I see the problem. It's not just QM, or even relativistic Quantum Field Theory. You have to factor in general relativity, and no-one has yet managed to combine the two. Unless Hawking is saying he has? *Gets excited*
Posted by fallow (Member # 6268) on :
KoM,
Unlikely, without a new mathematical grammar. That kind of development would seem hard to keep under wraps.
fallow
Posted by King of Men (Member # 6684) on :
To be sure, but if anyone could do it, it would be comrade Hawking. It's not as though he communicates easily.
Posted by Hobbes (Member # 433) on :
quote:1. A black hole sucks something in. We see it happen. 2. At some later time (from our frame of reference, of course) we get a glimpse AGAIN of what that something is/was. 3. The "thing" wasn't destroyed or totally absorbed like we used to think it should be. Instead, we see it as it used to be -- i.e., it somehow survived.
That means that we can view the past by looking into the future -- um, okay, I maybe skipped a step or two. But is this what he's saying?
Actually Bob, you got to the right concluesion but in the wrong way.
The orginal theory is that asa things become sucked into the blackhole, the only information about what those things were that's left to the universe is their total mass. In other words, once somethings been sucked past the Event Horizon the only effect it has on the rest of the universe is the increased Schwarzschild radius that results. Actually, this lead to some interesting effects.
It was then theorizied that since any reaction must increase entropy, black holes were not possible. Why? Well take a reaction, say a motorcycles powering away. When you run that motorbike it releases energy and thus, increases the overal entropy of the universe. But if you take that motorbike, start it up by a black hole and throw it in, all evidence of the entropy is gone, and wont effect the universe. So you've created entropy and then hid the act for the universe, this is impossible physically. Well another physcist actually came up with a solution that Hawking (kind of and relectantly with changes) accepted. That the event horizon is actually a measure of the total entropy of the black hole. The problem that created is that to have entropy, there must be a temperature, and to have temperature there must be some sort of radiation. So Hawking discovered that black holes actually do release things once they've been sucked in, radiation (Hawking radiation as it's now called) is given out.
Anyways, back on track. What this states is that if a black hole sucks in say a car of 1000kg, that will have a different impact on the unvierse when it is released in energy form than the energy released would have if instead it had been a 1000kg pile of dirt.
But remember that this energy released, we wont be seeing the car or the dirt coming back out full formed, rather just that the energy released (the frequency, amplitude, and what not) will be different when released from the car rather than the dirt. So techincally we can use this information to look into the past, but the fact that it's physically possible does mean it's feasible. It would be like picking up a book and trying to track down the exact origin of one of the water dropelts that helped moisturize the tree whose acorn gave root to the tree that was cut down to use for the paper. Only harder.
Hobbes Posted by King of Men (Member # 6684) on :
Minor quibble : The mass of the object sucked in is not the only thing that you can see. Black holes also have angular momentum, electric charge, and presumably the other forms of charge as well. So the spin and charge of an electron, say, are transferred to the black hole as the electron is sucked in, along with the mass.
Posted by TMedina (Member # 6649) on :
It's a rare gift to take a complex concept and pare it down to comprehensible bits for those of us unable to comprehend the larger concept en masse.
My father has a PhD in Chemistry and I learned early not to ask him questions - what should have been a 30-second answer would turn into half an hour of elementary chemistry and commentary.
-Trevor
Posted by Bob_Scopatz (Member # 1227) on :
Hobbes,
You should write science textbooks.
That was beautiful.
Posted by Hobbes (Member # 433) on :
Thanks Bob.
quote:It's a rare gift to take a complex concept and pare it down to comprehensible bits for those of us unable to comprehend the larger concept en masse.
My father has a PhD in Chemistry and I learned early not to ask him questions - what should have been a 30-second answer would turn into half an hour of elementary chemistry and commentary.
Yah, I agree, Hawking really has a gift, not as much as Feynman but still, a gift.
And it sounds like you're describing my (physics proffesor) father. I'd ask him a question about 6th grade algebra and all of a sudden equations would start showing respect to the 'x' variable.
Hobbes Posted by Hobbes (Member # 433) on :
Ohh, and KoM is right, the velocity an charge do effect the outside universe once the matter crosses the event horizon, but the point is that if you take a car and throw it in it would have exactly the same effect on the rest of the universe (when it comes out of the black hole) as if you'd takes that care, melted it down into steel ignots and thorwn those in.
[EDIT: in the old theory, not the new one ]
Hobbes
[ July 17, 2004, 02:06 PM: Message edited by: Hobbes ]
Posted by Jutsa Notha Name (Member # 4485) on :
Just a nitpick: could you please edit the title? I know it's a minor thing, but constantly seeing Stephen misspelled keeps throwing me off from even trying to read. It's like a mental speedbump. Sorry.
Posted by Hobbes (Member # 433) on :
Ahh yes, spelling, someone tried to teach me that in school. I hope they got paid well because they aren't going to get any other non-material benefits from tring to teach spelling to me.
Hobbes Posted by Jutsa Notha Name (Member # 4485) on :
That's okay, though. It just means when you write any technical presentations or papers, you just make use of one of those whose strengths are in spelling. It all balances out in the end.
Posted by rivka (Member # 4859) on :
quote: And it sounds like you're describing my (physics professor) father. I'd ask him a question about 6th grade algebra and all of a sudden equations would start showing respect to the 'x' variable.
*giggle* Your dad sounds an awful lot like my dad, Hobbes. (Mine is actually a mathematical physics professor. According to my mom (a mathematician) that makes him neither a mathematician nor a physicist. )
[Addit: and my dad can't spell either. Good thing his secretary can . . . ]
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