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rhinoceros
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virus: Hawking peeks inside black holes
« on: 2004-07-15 10:38:19 » |
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Hawking cracks black hole paradox
Mew Scientist, 14 July 04
http://www.newscientist.com/news/news.jsp?id=ns99996151
After nearly 30 years of arguing that a black hole destroys everything
that falls into it, Stephen Hawking is saying he was wrong. It seems
that black holes may after all allow information within them to escape.
Hawking will present his latest finding at a conference in Ireland next
week.
The about-turn might cost Hawking, a physicist at the University of
Cambridge, an encyclopaedia because of a bet he made in 1997. More
importantly, it might solve one of the long-standing puzzles in modern
physics, known as the black hole information paradox.
It was Hawking's own work that created the paradox. In 1976, he
calculated that once a black hole forms, it starts losing mass by
radiating energy. This "Hawking radiation" contains no information about
the matter inside the black hole and once the black hole evaporates, all
information is lost.
But this conflicts with the laws of quantum physics, which say that such
information can never be completely wiped out. Hawking's argument was
that the intense gravitational fields of black holes somehow unravel the
laws of quantum physics.
Other physicists have tried to chip away at this paradox. Earlier in
2004, Samir Mathur of Ohio State University in Columbus and his
colleagues showed that if a black hole is modelled according to string
theory - in which the universe is made of tiny, vibrating strings rather
than point-like particles - then the black hole becomes a giant tangle
of strings. And the Hawking radiation emitted by this "fuzzball" does
contain information about the insides of a black hole (New Scientist
print edition, 13 March).
Big reputation
Now, it seems that Hawking too has an answer to the conundrum and the
physics community is abuzz with the news. Hawking requested at the last
minute that he be allowed to present his findings at the 17th
International Conference on General Relativity and Gravitation in
Dublin, Ireland.
"He sent a note saying 'I have solved the black hole information paradox
and I want to talk about it'," says Curt Cutler, a physicist at the
Albert Einstein Institute in Golm, Germany, who is chairing the
conference's scientific committee. "I haven't seen a preprint [of the
paper]. To be quite honest, I went on Hawking's reputation."
Though Hawking has not yet revealed the detailed maths behind his
finding, sketchy details have emerged from a seminar Hawking gave at
Cambridge. According to Cambridge colleague Gary Gibbons, an expert on
the physics of black holes who was at the seminar, Hawking's black
holes, unlike classic black holes, do not have a well-defined event
horizon that hides everything within them from the outside world.
In essence, his new black holes now never quite become the kind that
gobble up everything. Instead, they keep emitting radiation for a long
time, and eventually open up to reveal the information within. "It's
possible that what he presented in the seminar is a solution," says
Gibbons. "But I think you have to say the jury is still out."
Forever hidden
At the conference, Hawking will have an hour on 21 July to make his
case. If he succeeds, then, ironically, he will lose a bet that he and
theoretical physicist Kip Thorne of the California Institute of
Technology (Caltech) in Pasadena made with John Preskill, also of Caltech.
They argued that "information swallowed by a black hole is forever
hidden, and can never be revealed".
"Since Stephen has changed his view and now believes that black holes do
not destroy information, I expect him [and Kip] to concede the bet,"
Preskill told New Scientist. The duo are expected to present Preskill
with an encyclopaedia of his choice "from which information can be
recovered at will".
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LenKen
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Re: virus: Hawking peeks inside black holes
« Reply #1 on: 2004-07-15 13:53:16 » |
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Hawking peeks inside black holes? Is the CoV mailing list really the place for sexual innuendo?
That reminds me of something Stephen Hawking mentioned in his book The Universe in a Nutshell. But rather than getting the book out of my bedroom and quoting the actual passage, I’ll simply pinch something from a review of that book that I just Googled—so I don’t have to get up and walk to another room to retrieve the book. Whew!
“Stephen Hawking Explains the Big Picture”
by Deirdre Donahue, USA Today
“For a book on physics, there is an unexpected touch of the ribald to The Universe in a Nutshell. Hawking describes a 1963 trip to Paris to present a seminar on his discovery that quantum theory meant that ‘black holes are not completely black.’ Hawking writes that it was not a big success. First, the French scientists at that point did not believe in black holes. And the name repelled them. Their translation, trou noir, had ‘dubious sexual connotations.’”
source: http://www.usatoday.com/life/books/2001-12-19-stephen-hawking.htm
It’s hard for an atheist
with a god complex
to believe in himself. —LenKen
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rhinoceros
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Re: virus: Hawking peeks inside black holes
« Reply #2 on: 2004-07-15 15:00:23 » |
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Heh, Hawking is not unfamiliar with bets. Here is a copy of another bet
he made, one year's subscription to the Penthouse magazine.
http://www.kent.k12.wa.us/staff/trobinso/physicspages/Web/1999PoP/Hawking/Didyouknow.html
By the way, Nature has some more information on Hawking's new black hole
theory.
http://www.nature.com/news/2004/040712/full/040712-12.html
<quote>
The remarkable about-face is the result of Hawking's attempts to combine
quantum theory with general relativity in a powerful new theory of
quantum gravity. Hawking is due to present his latest ideas at the 17th
International Conference on General Relativity and Gravitation, which
runs from 18 July to 23 July in Dublin, Ireland. But he gave a preview
of the talk at his department in Cambridge University last month.
He has been using a mathematical technique called the "Euclidean path
integral". The technique is extremely complex as it lumps all the
possible histories of a system into one equation. First used by quantum
physicist Richard Feynman, it has generally been applied to subatomic
particles. But Hawking has been working for several years to apply the
idea to black holes.
"The view seems to be forming in his mind that there isn't a black hole
in the absolute sense, there's just a region where things take a very
long time to escape," says Gibbons. This suggests that black holes do
not actually narrow to a singularity at all.
The great escape
So an object falling into a black hole is not completely obliterated.
Instead, the black hole is altered as it absorbs the object. Although it
would certainly be very difficult to retrieve any information about that
object, the data are still there, somewhere inside the black hole,
Gibbons says.
How could that information ever escape? The answer lies in one of
Hawking's greatest discoveries: that black holes slowly evaporate into
space by losing particles from the very edge of the gravitational
precipice at their rim, called Hawking radiation. The black hole
eventually shrinks to a tiny kernel, at which point a growing torrent of
radiation begins to leak out, potentially carrying the lost information
with it.
But Preskill says that Hawking's new take on quantum gravity rests on
shaky mathematical foundations, and is unlikely to be embraced by the
physics community. "I am sceptical about whether he has found a fully
satisfactory resolution to the problem," he says.
<end quote>
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