Black Holes

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JerryB, apart from Hawking radiation, there aren't really any other mechanisms for extracting mass from a black hole. As Eburacum45 says, any "normally" produced black-hole, i.e. one generated by stellar collapse, etc., would radiate like a blackbody at a fairly low temperature. (The bright ones, would be the small ones, produced by more obscure processes. :) ) Eventually they might (assuming that Hawking was correct) radiate away to nothingness, but you would have to wait a hell of a long time. (Heat death of the unverse, kind of long time. ;) )
 
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Eventually they might (assuming that Hawking was correct) radiate away to nothingness, but you would have to wait a hell of a long time. (Heat death of the unverse, kind of long time. )

10^99 years for a galactic mass black hole, evidently; long after all the protons in the universe have decayed.
 

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So does this mean that all black holes created by collapsing stars live on until the universe ceases to exist? They just keep getting bigger?
 
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JerryB said:
So does this mean that all black holes created by collapsing stars live on until the universe ceases to exist? They just keep getting bigger?
Well, no,
but they will still be absorbing the fantastically small amount of energy around in the universe till about 10^97 years;
there will be one or two photons and neutrinos per cubic lightyear, but Hawking radiation is so slow for the massive black holes that the input is still more than the output.
Some time after 10^97 this changes, and after that time the black hole gets smaller until it evaporates around about 10^99.

If we are still around this liberation of energyfrom evaporating black holes might be enough to fuel civilisation for an unknown period of time; but seeing as proton decay will have destroyed all solid matter back at 10^37 years from now, I don't know what physical formthis civilisation might take.
 
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Very fancy talk we are still talking about a hole in reality. Words and equations mean nothing.
 
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I remember reading a SF novel years ago where the star ships used small black holes in magnetic bottles for energy. They would would release hydrogen into the bottle and as it spun down to the event horizon lots of energy would be released and they would use this in propulsion. Workable?
:spinning
 

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John Worfin said:
I remember reading a SF novel years ago where the star ships used small black holes in magnetic bottles for energy. They would would release hydrogen into the bottle and as it spun down to the event horizon lots of energy would be released and they would use this in propulsion. Workable?
:spinning
Actually it wouldn't matter what you chucked in.

Whether it would yield enough energy to shift the ship includng the mass of the black hole, I don't know, anyone got a calculator?

The hole would have to have a fair bit of mass if it wasn't going to evaporate through Hawking energy.

And of course you've got to find or make your mini-black hole.
 

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prometheus said:
Very fancy talk we are still talking about a hole in reality. Words and equations mean nothing.
How can we be 'talking about a hole in reality' (or anything else for that matter) if 'words...mean nothing'?
 
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Inverurie Jones said:
They've worked okay so far...
I beg to differ. The scientific definition of light is the ability to do work. Having your science teacher tell you this is quite amusing. Even a small child can tell the ability to do work is infact discribing what light is able to do not what light actualy is.

Light has the properties of infanite length and mass. The term infanite is not a scientific term infact it is a religious one. Also time disobays The Laws of Thermol Dynamics because for light there is no time. At the speed of light time is zero. Zero also is not a scientific number. It is not a real number. It is a purely imaganary number created by the mind of an observer. The scientific rational is quite clear how can one have something or a unit of nothing. Of course the concept is ubsured yet it is held as scientific fact.

Any investigation into the universe useing scientific rational always ends rather quickly with web of contradiction. The only way to corectly examine ones envirionment is through phyilisophical analysis. Phyilosiphy has no presoposed Laws. This is why not one Law of scinence has a universal aplication.
The definition of a thought is not a word. Thinking is how one understands.
 
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John Worfin said:
I remember reading a SF novel years ago where the star ships used small black holes in magnetic bottles for energy. They would would release hydrogen into the bottle and as it spun down to the event horizon lots of energy would be released and they would use this in propulsion. Workable?
:spinning
You can just use a tiny black hole, and as quick as you chuck things in, it will be evaporating energy out- direct conversion of matter to energy.
The difficulties include-
-pushing matter into a black hole against the pressure of the energy coming out is difficult at this scale; the gravity of a small black hole is not very high until you are a fraction of a centimetre away from the event horizon.
-holding on to the black hole against acceleration- it is massive, tiny and white hot.
Luckily it will retain an electric charge.
 
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prometheus said:
Very fancy talk we are still talking about a hole in reality. Words and equations mean nothing.
But the only knowledge that we have about black holes is through the equations. It is through the equations that people can determine what properties these beasts might have and then go looking for them. If you can demonstrate the existance of these "holes in reality" without having to refer back to the predictions arising from the equations, I would be very impressed. :)
 
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prometheus said:
I beg to differ. The scientific definition of light is the ability to do work.
Where did you come across that definition? It's certainly not one that I'm familiar with. Websters defines it more convincingly as
"a : something that makes vision possible b : the sensation aroused by stimulation of the visual receptors c : an electromagnetic radiation in the wavelength range including infrared, visible, ultraviolet, and X rays and traveling in a vacuum with a speed of about 186,281 miles (300,000 kilometers) per second; specifically : the part of this range that is visible to the human eye"

This would seem to be a better match. :)

What you're actually defining is the concept of "energy."


Having your science teacher tell you this is quite amusing.

I'd complain, because if that is the definition given to you by your teacher, then it is plain wrong. :)


Light has the properties of infanite length and mass.

Again, I'm not sure where this comes from. I don't recognise it. (People tend to get a bit agitated if they try to do a Lorentz transformation into the photon's rest-frame because the transformations blow up.)


Any investigation into the universe useing scientific rational always ends rather quickly with web of contradiction. The only way to corectly examine ones envirionment is through phyilisophical analysis. Phyilosiphy has no presoposed Laws. This is why not one Law of scinence has a universal aplication.
The definition of a thought is not a word. Thinking is how one understands.

Don't really follow how this works. Science doesn't really have any pre-supposed laws. There are much cherished laws that people might be unhappy about losing, but all of scientific knowledge is contingent on it being able to accurately represent the observable universe. As soon as it doesn't, it (eventually, after much weeping) is replaced by a better representation. Take, for example, the way that Einstein's relativistic mechanics has superceded Newton's. (Though Newton's can still be employed usefully to non-relativistic scenarios.) :)
 

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Blakc holes redefined

Black holes redefined by a jet of rays

Heather Catchpole
ABC Science Online

Thursday, 15 January 2004



The definition of a black hole may need to change now that an international team of astronomers has discovered one of its defining characteristics elsewhere.

The team was the first to detect a binary star system emitting high-speed jets. Previously, these jets were thought to be a characteristic of black holes.

Dr Rob Fender from the University of Amsterdam led the research team, which included Australian and U.K. researchers. They reported their find in today's issue of the journal Nature.

Black holes have an enormous gravity and suck in any matter than comes close. They sometimes release some of this material in high-speed jets that can be seen by a telescope as a sudden flash of x-rays. So far, these jets have only been found around black holes, which are extremely massive objects.

But the researchers have for the first time seen jets coming from a binary star system with no black hole. This means the presence of these jets can no longer be a determining factor in the definition of black holes.

The system is in the constellation of Circinus and can be seen during the winter in Southern skies. It consists of a neutron star in orbit with a much smaller companion star. The neutron star sucks in matter that falls towards it from its companion star. Some of this matter is then being flung back out as high-speed jets.

Black holes not necessary

Australian team member Dr Helen Johnston, from the University of Sydney, told ABC Science Online the researchers were surprised to see something being accelerated at such a large fraction of the speed of light, without the presence of a black hole.

"It tells us something important: that whatever is doing the accelerating doesn't depend on there being a black hole there," said Johnston.

The discovery reopens the debate about what causes the jets, said Johnston. It indicates all that's needed for their formation is the presence of an accretion disc, or orbiting ring of matter, around a massive object such as a black hole or a neutron star.

Looking at the jets will help astronomers understand what happens during the formation of an accretion disc, said Johnston.

Although the jets are only found around massive objects like black holes and neutron stars, accretion discs also form around normal stars, such as our Sun, eventually coalescing into planets and asteroids.

"We think the entire accretion disc [in this binary system] must be destroyed when the stars get so close there just isn't enough room for the disc to survive. All the material from the disc falls into the star at once, causing an explosion, and that's what causes the massive burst of x-rays.

"[The disc] is forming and being destroyed once every 16 days and then reforming. That's really fast. That's pretty important because accretion discs are ubiquitous in everything from forming planets all the way out to quasars."
http://www.abc.net.au/science/news/stories/s1025400.htm
 

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prometheus said:
Light has the properties of infanite length and mass. The term infanite is not a scientific term infact it is a religious one.
I won't lie to you: When I read that, my bullshit-meter went off. No offense, my language is like this. Could you please elaborate upon this?

Aren't you just contradicting yourself here, by stating something (using words) and not offering proof? In religious terms, I can see how infinite can be related to god. But that is an opinion. Moreso than a scientific observation. I can say that there are 10^39 particles of sand in the world, or an infinite. That would be an opinion.

If, however, based upon certain (albeit somewhat reliable) observations, equations could be formed, then saying infinite, if that turned out to be the case, would be less of an opinion and more of a closer-to-truth statement.

Again, no offense intended. I may be less-learned!!
 

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Black Hole "Ripped Star Apart"

Just thought this was pretty cool!

Black hole 'ripped star apart'
February 19, 2004

TWO space observatories have provided the first strong evidence of a super-massive black hole stretching, tearing apart and partially gobbling up a star flung into reach of its enormous gravity, astronomers said today.
You can read the full article here:
http://news.com.au/common/story_page/0,4057,8727402%5E401,00.html
CNN also have an article here:
http://www.cnn.com/2004/TECH/space/02/18/shc.blackhole.star/index.html

This would most certainly would have been a sight to see if you were in the neighbourhood hehe! (And impervious to gravitational pulls!)
 
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It makes me wonder what would happen if a star and a black hole were on a perfect collision course.
The black hole would swallow the star whole, immagine the energy given off, surely it would be cataclismic.
Would it be possible to "blow up" the black hole with all that energy and possibly break it into smaller black holes?
Does Stephen Hawking visit this board?
Maybe he would know.
 

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haha stephen u there mate?

heh, it would be interesting to know what would happen if they collided directly. especially if the star was larger in size than the black hole.

it would probably have the same sort of effect as say, water spiraling down into a plug hole.
 

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AFAIK, as the space-time compression at the star/blackhole manifold would be arbitrarily large enough to negate any initial velocity or trajectory differential. Size or mass or the star wouldn't be a problem either.

However, the temporal problems would be interesting as an observer would see, given a long enough time, a complete obliteration of the parent star, but an observer on the star itself would in comparison take in infinite time to experience spaghettification, but the observer himself would experience it real-time... I think.

*buzz* Mr Hawking to "'Black Hole "Ripped Star Apart'" please
 

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Big Black Hole Rips Up Star, Then Eats the Crumbs

Superb headline!!!! Good stroy too ;)

Big Black Hole Rips Up Star, Then Eats the Crumbs

Wed Feb 18, 4:21 PM ET

Add Science - Reuters to My Yahoo!

By Deborah Zabarenko

WASHINGTON (Reuters) - A big black hole ripped apart a sun-like star, gobbled a bit of it and flung the rest out into the cosmic neighborhood in an act of celestial gluttony caught by two orbiting observatories, scientists said on Wednesday.



The doomed star probably went off-course and into the supermassive black hole's path after a close encounter with another star, according to astronomers using NASA (news - web sites)'s Chandra X-ray Observatory and the European Space Agency's XMM-Newton X-ray Observatory.

As the star approached the heart of a galaxy some 700 million light-years from Earth, the black hole lurking there stretched the star and ultimately tore it into bits. A light-year is about 6 trillion miles, the distance light travels in a year.

"Stars can survive being stretched a small amount ... but this star was stretched beyond its breaking point," said Stefanie Komossa, leader of the international team of researchers who detected the event.

"This unlucky star just wandered into the wrong neighborhood," Komossa said in a statement.

Aside from the sheer violence of the event, astronomers believe this is strong evidence to support a long-held theory that black holes are capable of pulling in cosmic bodies, stretching them until they break and then consuming them.

"This is one of the Holy Grails of astronomy," Alex Filippenko, a professor at the University of California-Berkeley, said at a briefing at NASA headquarters.

COSMIC X-RAYS

Astronomers have had evidence since the 1960s that some galaxies emit extremely strong electromagnetic radiation, thought to be spawned by a swirl of material being sucked into each galaxy's central black hole, Filippenko said.

Such a powerful outburst occurred at the heart of a seemingly quiet galaxy, RX J1242-11, which looked normal in optical telescopes based on the ground.

However, the Chandra and XMM-Newton observatories look at the cosmos by tracking X-rays, which means that they can peer through the cosmic gas and dust to detect things that optical telescopes cannot see.

These two observatories indicated that the outburst was caused when gas from the ripped-up star was heated millions of degrees as part of it was pulled into the black hole.

Some fraction of the star -- more than 1 percent, less than 25 percent -- was drawn into the black hole, while the rest of it was dispersed into the surrounding galaxy, the astronomers said at the briefing.

The force that dragged the star to its death is an extreme example of what is known as tidal disruption, the same kind of gravitational pull that the moon exerts on big bodies of water on Earth.

Tidal disruption of a star probably happens about once every 10,000 years in a typical galaxy, the scientists said. And a star that wanders close to a black hole is not necessarily dismembered and partially eaten, they said.

Some could be swallowed whole, while others might be forced to spin exponentially faster than their normal rotation rate.

This happened far from Earth in the constellation Virgo, but could have implications for our Milky Way, which like most galaxies harbors a big black hole in its heart.




However, our sun lies fairly far from the galactic center, some 25,000 light-years away, and recent surveys indicate that there are no stars close enough to the Milky Way's black hole to be dragged into its maw.

"None of the stars that we currently see at the center of our galaxy is in immediate danger of being swallowed," Filippenko said.

More information is available online at http://chandra.harvard.edu.
Source
 

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Missing Black Holes Found

By Robert Roy Britt
Senior Science Writer
posted: 06:00 am ET
28 May 2004



European researchers have found 30 previously hidden supermassive black holes anchoring faraway galaxies, which suggests there at least twice as many of the colossal gravity wells as thought.

Supermassive black holes hold as much matter as millions or billions of suns. The newfound black holes were long sought but went unnoticed because they lurk behind veils of dust and are so faraway that even the galaxies they anchor are difficult to examine in any detail.

"This discovery means that surveys of powerful supermassive black holes have so far underestimated their numbers by at least a factor of two, and possibly by up to a factor of five," said study leader Paolo Padovani from Space Telescope-European Coordinating Facility and the European Southern Observatory in Munich, Germany.

They were found using the Astrophysical Virtual Observatory (AVO), a database of observations from various telescopes. Making the detections required analyzing views from three telescopes: the orbiting Hubble Space Telescope and Chandra X-ray Observatory; and the European Southern Observatory's Very Large Telescope in Chile.

The black holes were all in "active" galaxies, meaning they were actively consuming large quantities of galactic matter. Our Milky Way contains a supermassive black hole but the setup is not currently active. In an active galaxy, a swirling disk of gas and dust, known as a torus, surrounds and largely obscures the central black hole.

The torus looks something like a donut. Inside it is a thinner disk of material, called an accretion disk, that spirals in toward the black hole and is accelerated to a significant fraction of light-speed.

Black holes cannot actually be seen, because they trap all matter and light that enters them. But if an active galaxy is viewed from above, the hole in the middle of the torus allows a good view of the accretion disk, allowing astronomers to infer the presence of the black hole.

The new study looked at galaxies that were edge-on, but deduced the black holes by studying emissions in various wavelengths of the electromagnetic spectrum.

The observations in the AVO database were originally made as part of the Great Observatories Origins Deep Survey (GOODS), which has taken two patches of deep sky and made them the best studied in multiple wavelengths.

"These discoveries highlight the kind of scientific impact that Virtual Observatory technologies and standards will have on astronomy world-wide", said Peter Quinn, director of the AVO.

The findings will be detailed in a future issue of the journal Astronomy & Astrophysics.
http://www.space.com/scienceastronomy/blackholes_missing_040528.html
 

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Massive Black Hole Stumps Researchers

By Tariq Malik
Staff Writer
posted: 06:30 am ET
28 June 2004



A team of astronomers have found a colossal black hole so ancient, they're not sure how it had enough time to grow to its current size, about 10 billion times the mass of the Sun.

Sitting at the heart of a distant galaxy, the black hole appears to be about 12.7 billion years old, which means it formed just one billion years after the universe began and is one of the oldest supermassive black holes ever known.

The black hole, researchers said, is big enough to hold 1,000 of our own Solar Systems and weighs about as much as all the stars in the Milky Way.

"The universe was awfully young at the time this was formed," said astronomer Roger Romani, a Stanford University associate professor whose team found the object. "It's a bit of a challenge to understand how this black hole got enough mass to reach its size."

Romani told SPACE.com that the black hole is unique because it dates back to just after a period researchers call the 'Dark Ages,' a time when the universe cooled down after the initial Big Bang 13.7 billion years ago. That cooling period lasted about one billion years, when the first black holes, stars and galaxies began to appear, he added. The research appeared June 10 on the online version of Astrophysical Journal Letters.

Invisible to the naked eye, black holes can only be detected by the radiation they spew and their gravitational influence on their stellar neighbors. Astronomers generally agree that black holes come in at least two types, stellar and supermassive. Stellar black holes form from collapsed, massive stars a few times the mass of the Sun, while their supermassive counterparts can reach billions of solar masses.

A supermassive black hole a few million times the mass of the Sun is thought to sit at the center of our own Milky Way galaxy, and some of the largest supermassives seen date have reached up to two billion solar masses, researchers said.

Weighing a black hole heavyweight

Determining a precise mass for the black hole found by Romani's team, dubbed Q0906+6930, is a bit tricky though since it's so far away.

"Very massive black holes like this are so rare, that one should really be a little suspicious at first," Romani said.

The black hole, called a blazar because it spews jets of radiation in roughly the direction of Earth, sits at the center of a galaxy about 12.7 billion light-years away in the constellation Ursa Major. One light-year is the distance light travels in one year, is about six trillion miles (10 trillion kilometers).

Because the blazar is so distant, there are no nearby neighbors to scan for potential gravitational effects, and much of its radiation is absorbed by gas and dust lying between it and the Earth, Romani said.

"It really is too far away to do a direct orbital measurement to help determine its mass," Romani said, adding that he and his colleagues had to estimate the mass based on a quantitative method that includes measuring particle velocity and the Doppler shift of its infrared emission lines. "The best thing to do is study it in a broader region of the spectrum, to get more emission lines."

Next year, researchers plan to scan the blazar's X-ray emissions with the Very Large Baseline Array and take other measurements to pin down a more accurate mass for the object, and eventual gamma-ray studies could refine that number even more.

A good catch

The blazar found by Romani and his colleagues is one of about 200 they have catalogued to date in preparation for the Gamma Ray Large Area Space Telescope (GLAST) planned for launch in 2007. The researchers are using a collection of optical, gamma-ray and radio observations for their study.

Since that mission is aimed at studying high-energy radiation sources like pulsars and spinning neutrons stars and others, researchers wanted to be able to filter out blazar interference before GLAST begins operations. But the discovery of blazar Q0906+6930, has yielded a few added scientific benefits.

"It suggests the blazar phenomena turned on much earlier than we thought," Romani said of the black hole. "So it really pushes on the formation scenarios we have for black holes."

Close study of the blazar's jet could also give astronomers a good picture of all the matter lying between Earth and the massive black hole since it has to pass through such material to reach astronomers' telescopes.

"So that's a way of using this weird, anomalous object to help our understanding of the universe," Romani said, adding that he and his colleagues plan to continue their blazar hunt until GLAST begins. "But I would be very surprised if there were a large number of these objects."
http://www.space.com/scienceastronomy/heavy_blazar_040628.html

Emps
 

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Black holes don't destroy all information...

Stephen Hawking thinks he might have been wrong...

At:
http://www.newscientist.com/news/news.jsp?id=ns99996151

Hawking cracks black hole paradox

Jenny Hogan

19:00 14 July 04

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."




Subscribe to New Scientist for more news and features

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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Hawking Rethinks Black Holes

Physicist Rethinks Theory on Black Holes

By SHAWN POGATCHNIK, Associated Press Writer

DUBLIN, Ireland - After 29 years of thinking about it, Stephen Hawking says he was wrong about black holes. The renowned Cambridge University physicist presented a paper Wednesday arguing that black holes, the celestial vortexes formed from collapsed stars, preserve traces of objects swallowed up and eventually could spit bits out "in a mangled form."

Hawking's radical new thinking caps his three-decade struggle to explain a paradox in scientific thinking: How can objects really "disappear" inside a black hole and leave no trace, as he long believed, when subatomic theory says matter can be transformed but never fully destroyed?

Hawking had previously insisted that black holes destroy all molecular fingerprints of their contents and emit only a generic form of radiation.

But on Wednesday at the 17th International Conference on General Relativity and Gravitation, Hawking presented mind-boggling new calculations that suggest black holes are able to cast out their contents — and that there's only one way in and one way out.

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. The latest theory offers hope that scientists one day may identify the history of what a black hole has taken in over the eons — by decoding what it emits.

"There is no baby universe branching off (inside a black hole), as I once thought. The information remains firmly in our universe," Hawking said in a speech to about 800 physicists and other scientists from 50 countries. "I'm sorry to disappoint science fiction fans, but if information is preserved, there is no possibility of using black holes to travel to other universes.

"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."

Hawking's new theory produced waves of skepticism and puzzlement from leading physics professors. Two in the front row — William Unruh of the University of British Columbia and Robert Wald of the University of Chicago — shrugged and shook their heads in disbelief as Hawking spoke.

"Hawking is completely revising his prior belief that what goes into a black hole is washed out. Now he believes that anything emitted from a black hole can be identifiable back to its source," said Wald, an expert on black holes. "He's running away from what we still believe."

Unruh said: "Part of the problem is he's providing so few details, so it's impossible to know whether we can believe these calculations. Stephen Hawking's not stupid, so we're going to take what he says seriously ... but the whole theory we're hearing seems extremely speculative."

Not long ago, Hawking was just as certain that black holes destroyed whatever they took in.

In 1997, he and Caltech physics professor Kip Thorne made a well-publicized bet with a particle physicist, John Preskill, that "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."

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."

On Wednesday, Hawking ended his lecture by saying he had proved that Preskill was right after all. Preskill received an encyclopedia on baseball as his reward.

Preskill said he was pleased to have won the bet with so many witnesses present, but was sad too. "It's been so much fun talking about this issue for such a long time. What are we going to argue about now?" he said to laughter.

Preskill said he was looking forward to seeing Hawking's much more detailed paper on the subject next month. "I'll be honest — I didn't understand the talk," he said.

Hawking shot to international fame in 1988 with his best-selling book "A Brief History of Time," which sought to explain to a general audience the most complex aspects of the universe.

He had already been famous in physics circles since the mid-1970s, when he postulated that black holes could eventually evaporate and disappear, emitting radiation as they die. That radiation has been named "Hawking radiation" in his honor.

Despite being virtually paralyzed and wheelchair-bound with amyotrophic lateral sclerosis since his mid-20s, Hawking travels the world on speaking engagements. He communicates by using a hand-held device to select words on his wheelchair's computer screen.

The slow process of constructing answers Wednesday meant Hawking could answer only two questions in the half-hour news conference that followed his lecture. The final questioner asked what problem he planned to tackle next, now that the paradox of the black hole was out of the way.

"I don't know," Hawking quickly replied, bringing the house down with laughter.

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Word of warning: don't read this and then mutter out to yourself(as I did) "Well just how many black holes has he been in?" Your co-workers or friends will stare.
 
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Anonymous

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I didn't understand his original theory either. I must make more effort :)
 

escargot

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I have Hawking's 'Brief History of Time' on the shelf. Every now and then I take it down, leaf through it, shake my head and put it back. :D

One day I'll be ready to read it.
 
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Anonymous

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Oddly, it isn't the reading bit I am short on. It's understanding that I can't achieve :)
 

Mighty_Emperor

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Well wet my pants this seems unwise mad science (I like it!!):

Lab fireball 'may be black hole'

A fireball created in a US particle accelerator has the characteristics of a black hole, a physicist has said.

It was generated at the Relativistic Heavy Ion Collider (RHIC) in New York, US, which smashes beams of gold nuclei together at near light speeds.

Horatiu Nastase says his calculations show that the core of the fireball has a striking similarity to a black hole.

His work has been published on the pre-print website arxiv.org and is reported in New Scientist magazine.

When the gold nuclei smash into each other they are broken down into particles called quarks and gluons.

These form a ball of plasma about 300 times hotter than the surface of the Sun. This fireball, which lasts just 10 million, billion, billionths of a second, can be detected because it absorbs jets of particles produced by the beam collisions.

But Nastase, of Brown University in Providence, Rhode Island, says there is something unusual about it.

Ten times as many jets were being absorbed by the fireball as were predicted by calculations.

The Brown researcher thinks the particles are disappearing into the fireball's core and reappearing as thermal radiation, just as matter is thought to fall into a black hole and come out as "Hawking" radiation.

However, even if the ball of plasma is a black hole, it is not thought to pose a threat. At these energies and distances, gravity is not the dominant force in a black hole.

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Story from BBC NEWS:
http://news.bbc.co.uk/go/pr/fr/-/1/hi/s ... 357613.stm

Published: 2005/03/17 11:30:41 GMT

© BBC MMV
Eureka! We've made a black hole

17 March 2005

There's no longer any need to travel into space to spot a black hole - one might already exist across the Atlantic.


A fireball which bears all the hallmarks of one of the universe's frightening creations has formed in New York, scientists claim.


But there's no need to panic - yet. This manmade version is not set to swallow anything - except, perhaps, the science rule book.


It was created after beams of gold nuclei were smashed into each other at a rate close to the speed of light. The intense heat generated forced the beams to break down into particles and form a ball of plasma about 300million times hotter than the surface of the Sun.

Some particles were absorbed by the fireball in the same way that black holes absorb matter. But researchers had to be quick to measure what was going on - it lasted for just 10million billion billionths of a second.


The experiment could prove ground-breaking, scientists at the Relativistic Heavy Ion Collider told New Scientist magazine.


But others are not so sure. Ed Shuryak, a physicist at Stony Brook University in New York, said: "It's very useful in that it will inspire thinking in that direction.


"But it's going to be another thing to see if it produces any fruit."

Black holes are usually remnants of stars that collapse under gravity after running out of fuel.


They have long fascinated sci-fi writers and film-makers because of the unusual physics which surround them.


The Red Dwarf crew was attacked by five at once and even Disney made a fantasy about them in the 1970s called, appropriately enough, The Black Hole.
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