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Rethinking Black Holes

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This story is a few days old but very, very interesting.

Science

No More Black Holes?

By Phil Berardelli

ScienceNOW Daily News

21 June 2007

If new calculations are correct, the universe just got even stranger. Scientists at Case Western Reserve University in Cleveland, Ohio, have constructed mathematical formulas that conclude black holes cannot exist. The findings--if correct--could revolutionize astrophysics and resolve a paradox that has perplexed physicists for 4 decades.

On the surface, a black hole seems like a simple concept. It's a point in space where gravity grows infinitely strong. At a particular distance from the center of the hole--called the event horizon--gravity is already so strong not even light can escape. So material falls in never to be seen again. Calculations support this theory, but they also support something stranger. In 1974, theoretical physicist Stephen Hawking showed that thanks to quantum mechanics matter can escape black holes in a tricky way. By random chance, a particle-antiparticle pair can flit into existence straddling the event horizon. One partner falls into the hole, while the other just barely makes it free. Because of this effect, dubbed Hawking radiation, a black hole slowly evaporates, so that anything that enters is eventually released over billions or even trillions of years. But how can black holes be both airtight and leaky?

Physicist Lawrence Krauss and Case Western Reserve colleagues think they have found the answer to the paradox. In a paper accepted for publication in Physical Review D, they have constructed a lengthy mathematical formula that shows, in effect, black holes can't form at all. The key involves the relativistic effect of time, Krauss explains. As Einstein demonstrated in his Theory of General Relativity, a passenger inside a spaceship traveling toward a black hole would feel the ship accelerating, while an outside observer would see the ship slow down. When the ship reached the event horizon, it would appear to stop, staying there forever and never falling in toward oblivion. In effect, Krauss says, time effectively stops at that point, meaning time is infinite for black holes. If black holes radiate away their mass over time, as Hawking showed, then they should evaporate before they even form, Krauss says. It would be like pouring water into a glass that has no bottom. In essence, physicists have been arguing over a trick question for 40 years.

Asked why then the universe nevertheless seems to be full of black holes, Krauss replies, "How do you know they're black holes?" No one has actually seen a black hole, he says, and anything with a tremendous amount of gravity--such as the supermassive remnants of stars--could exert effects similar to those researchers have blamed on black holes. "All of our calculations suggest this is quite plausible," Krauss says.

Not so fast, says astronomer Kimberly Weaver of NASA's Goddard Space Flight Center in Greenbelt, Maryland. Although she appreciates the physics the Case Western Reserve team is describing, the problem is "we have never observed any events that would back this up." At the site of the supermassive black hole at the center of the Milky Way, for example, she says astronomers routinely observe what looks like interstellar material disappearing without a trace. Also, no one has yet detected Hawking radiation, which would be prerequisite evidence for black hole evaporation, Weaver says.

Although it clearly presents the idea, I tend to think that article wasn't very well-written (in regard to some of the concepts). So I'll throw in an article from astronomy.com that adds a little more:

Rethinking black holes

A research team concludes it is impossible to lose something inside a black hole.

"Nothing there," Case Western Reserve University physicists concluded about black holes after spending a year working to calculate black hole formation. The research may solve the information-loss paradox that has perplexed physicists for the past 40 years.

"It's complicated and very complex," said Case physicists Tanmay Vachaspati, Dejan Stojkovic, and Lawrence Krauss, referring to the overall problem and their particular approach to solving it.

The physicists set out to discover just what happens once something enters and collapses into a black hole. In current thinking, once this happens, all information is lost. Yet, the researchers thought, if all information is lost, then laws of quantum physics are defied.

"If you define the black hole as some place where you can lose objects, then there is no such thing, because the black hole evaporates before anything is seen to fall in," Vachaspati said.

The team argues that information would remain forever on the event horizon — the black hole's point of no return. The masses on the edge of the incipient black hole appear to be collapsing, but never actually fall inside the event horizon.

Researchers began by collapsing nonsingular matter to see if an event horizon formed, signaling the creation of a black hole.

They found while mass shrank in size, the matter never collapsed inside an event horizon. Evidence of pre-Hawking radiation — a non-thermal radiation that allows information to be recovered from the collapsing mass — may be the explanation for this.

"Non-thermal radiation can carry information in it unlike thermal radiation. This means that an outside observer watching some object collapse receives non-thermal radiation back and may be able to reconstruct all the information in the initial object, and so the information never gets lost," the team said.

According to the researchers, if new black holes form, information formed in the initial state would disappear in the black hole after a burst of thermal radiation.

Using Schrodinger formalism, the researchers suggest that information about energy emitted from radiation is long-evaporated before an event horizon forms.

"An outside observer will never lose an object down a black hole," Stojkovic said. "If you are sitting outside and throwing something into the black hole, it will never pass over, but will stay outside the event horizon, even if one considers the effects of quantum mechanics. In fact, since in quantum mechanics the observer plays an important role in measurement, the question of formation of an event horizon is much more subtle to consider."

The Case team's findings could be the beginning of a new era in black hole research. "From an external viewer's point it takes an infinite amount of time to form an event horizon, and the clock for the objects falling into the black hole appears to slow down to zero," said Krauss, director of Case's Center for Education and Research in Cosmology.

"This is one of the factors that led us to rethink this problem, and we hope our proposal at the very least will stimulate a broader reconsideration of these issues," Krauss added.

If black holes exist in the universe, the astrophysicists speculate, they were formed only at the beginning of time.

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BLack holes are like giant tornados or shredders and they have been proven that they exist.

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I find that very interesting. Need to do some research. But it does make sense though. But heres the problem I have. Time runs the same everywere through our perspectives. If you were anywere in the universe then time would feel "normal" for you. It is not until we look from a different referance point. So i don't think that time can "stop". Because then everything would have to "stop". Light, matter, energy etc. And maybe even gravity then? (Because if all matter stopped all charges would stop so then matter would basically fall apart and all and with no mass you can't have gravity. And if theres no gravity then it wouldn't be a singularity in which case there would be time. LOL. Now thats another paradox to add to the paradox book :D)

Any comments to my solution????

:P

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BLack holes are like giant tornados or shredders and they have been proven that they exist.

They're not really like shredders, they're just objects with very large gravitational pulls (close up). And we know that something with a large gravitational pull exists at the centers of galaxies and elsewhere, we just usually take it to be black holes. As one of the articles I quoted says:

Asked why then the universe nevertheless seems to be full of black holes, Krauss replies, "How do you know they're black holes?" No one has actually seen a black hole, he says, and anything with a tremendous amount of gravity--such as the supermassive remnants of stars--could exert effects similar to those researchers have blamed on black holes. "All of our calculations suggest this is quite plausible," Krauss says.

But heres the problem I have. Time runs the same everywere through our perspectives. If you were anywere in the universe then time would feel "normal" for you. It is not until we look from a different referance point. So i don't think that time can "stop". Because then everything would have to "stop". Light, matter, energy etc. And maybe even gravity then? (Because if all matter stopped all charges would stop so then matter would basically fall apart and all and with no mass you can't have gravity. And if theres no gravity then it wouldn't be a singularity in which case there would be time. LOL. Now thats another paradox to add to the paradox book :D)

Any comments to my solution????

Time doesn't quite stop, it just gets slower and slower, going asymptotically to zero (i.e. crawling closer and closer to 0 but never quite reaching it). And this isn't really new or revolutionary: it's been known for decades that clocks tick slower deeper in gravitational wells (i.e. a clock at the base of a tower ticks slightly more slowly than one at the top). The result is that somebody at the top of the tower sees time for somebody at the bottom ticking more slowly and somebody at the bottom correspondingly sees it going faster for somebody at the top (though, both, as you note experience it flowing "normally" for themselves). With a black hole the well is a lot deeper than the one in which the ends of a tower on earth reside so the effect gets quite a bit more pronounced. When a star collapses, it faces the same problem as somebody falling toward a black hole: as it gets closer and closer to forming an event horizon time slows down more and more so that the time it takes to form tends toward infinity (i.e. the black hole is watching time speed up outside and pass through the universe's future history as it waits for the event horizon to form). But, apparently, the Hawking radiation that's predicted to evaporate a black hole over extremely long timescales is still going on and thus, in a sense, black holes evaporate before they actually form. So if you try to throw something into a black hole, it will take longer and longer to approach the event horizon the closer it gets--it would take an infinitely long time to cross, except the black hole itself wouldn't exist for an infinite time due to Hawking radiation, so it's effectively gone by the time the thing you threw makes it inside.

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This is only a very fine point. I mean, if this is true, it's not in any way substantially different than the former theory, except it clears up a couple of things that some people might have thought were paradoxes, but never seemed so paradoxical to me.

Maybe the loss of information was a paradox, for quantum physics. But the rest just seems weird, not paradoxical.

At any rate, it's not some great change, and the entities we refer to as "black holes" would still exist, just they are not precisely what we thought they were.

Harte

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It isn't different from existing theory. That the event horizon takes an infinite time to form is a well-known result of the classical calculations. It was just thought by some that taking quantum mechanics into account would lead to a finite formation time, which, if Krauss and his coauthors are correct, is not the case. Gravitational collapse certainly still occurs but black holes would never actually be the end product of that collapse.

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That's an absolutely fascinating article, but I'm not at all convinced. There is more than enough observable evidence that there are massive objects in the universe that swallow light and exert a very real gravitational force on other astral bodies. The stars at the center of the Milky Way have been shown to revolve around a common point. They move faster as they get closer, and slower as they move farther away, suggesting a very real attraction. The original article poses the question "how do we know those things are black holes?" Well----because those objects are what we've defined black holes to be. That's like asking how do we know that a couch is a couch. We've defined a certain object, with certain properties as a "couch" or as a "black hole." So the objects that we find matching that description are termed in the same way. We might very well be wrong about the physics involved or Hawking could have been wrong. Regardless---we know these objects exist, we've seen their effects. It's the same with Dark Energy and Dark Matter. The Universe should be slowing down given the amount of matter that exists. The fact that it's accelerating shows that there is obviously something else out there.

So in my mind, observations prove the existence of black holes.

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Posted (edited)

Everything can be "proven"or "disproven" by virtue of a formula.

The original observation of black holes was not mathematical but light anomalies that could only be explained if those things do exist.

The best example I have was the famous calculation of the maximum attainable speeds in the early 19th century, where a whole collegiate of physicist concluded that it would be impossible for a closed carriage to ever travel at a higher speed than 12 miles an hour because the passengers would suffocate.

Too bad Stevenson did not know that, he spoiled all those calculations with his train....

ED: Typo

Edited by questionmark

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(To lasy to qoute so bare with me)

One of you said that time slows down so much that the things are barely moving. And by the time it reaches the black hole its gone. I think i have to disagree. Time appears to almost stop from our perspective. Which is not universal time (because suposingly there is no "universal time"). So the time for the matter getting sucked is the same as ours here. Its not until we cross the two referance points with each other that we notice a difference. But if there ws a sentient being, being sucked in, time would feel the same as it does for you or me. If somehow you could send a human into it without the humans gettin ripped apart somehowm time would feel normal. Now, I have no idea were im getting at so ill just stop here.

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(To lasy to qoute so bare with me)

One of you said that time slows down so much that the things are barely moving. And by the time it reaches the black hole its gone. I think i have to disagree. Time appears to almost stop from our perspective. Which is not universal time (because suposingly there is no "universal time"). So the time for the matter getting sucked is the same as ours here. Its not until we cross the two referance points with each other that we notice a difference. But if there ws a sentient being, being sucked in, time would feel the same as it does for you or me. If somehow you could send a human into it without the humans gettin ripped apart somehowm time would feel normal. Now, I have no idea were im getting at so ill just stop here.

Is very useful anyway ... cause anybody can draw whatever conclusion they want to get at :devil:

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(To lasy to qoute so bare with me)

One of you said that time slows down so much that the things are barely moving. And by the time it reaches the black hole its gone. I think i have to disagree. Time appears to almost stop from our perspective. Which is not universal time (because suposingly there is no "universal time"). So the time for the matter getting sucked is the same as ours here. Its not until we cross the two referance points with each other that we notice a difference. But if there ws a sentient being, being sucked in, time would feel the same as it does for you or me. If somehow you could send a human into it without the humans gettin ripped apart somehowm time would feel normal.

This is probably true. What it means is that the individual falling into the hole would, had he a window, be able to watch the evolution of the universe occuring outside in extreme, extreme "fast forward" mode. If the black hole was massive enough, the Hawking radiation would evaporate it over a longer time period, meaning that the eyewitness might even be able to witness the end of the universe before he ever hit that event horizon.

The theory clearly states that he would at the very least witness the complete evaporation of the black hole before he ever reached the even horizon, which would itself never actually form anyway.

Harte

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The theory clearly states that he would at the very least witness the complete evaporation of the black hole before he ever reached the even horizon, which would itself never actually form anyway.

Making this the nearest thing to eternal physical life that we can imagine... what were those alchemists (of the first variety) looking for again?

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Posted (edited)

There is more than enough observable evidence that there are massive objects in the universe that swallow light and exert a very real gravitational force on other astral bodies. The stars at the center of the Milky Way have been shown to revolve around a common point. They move faster as they get closer, and slower as they move farther away, suggesting a very real attraction. The original article poses the question "how do we know those things are black holes?" Well----because those objects are what we've defined black holes to be. That's like asking how do we know that a couch is a couch. We've defined a certain object, with certain properties as a "couch" or as a "black hole."

Well, words are important because they're carrying concepts along with them. "Black hole" suggests a certain body with a certain structure that's understood in a very particular way. If Krauss et al. are right then it might be more accurate to go back to the old name for black holes: frozen stars. Sure, changing the name doesn't change what's at the center of galaxies but this isn't just quibbling over words, this is attempting to determine the very nature of just what those things are. For example, you mentioned dark matter and dark energy. Suppose dark matter turns out not to be an exotic new form of nonbaryonic matter but instead the effects are actually due to modifications of the physics governing gravitation. Certainly we'd have to think about altering the name. As for dark energy, at least one prominent cosmologist has suggested its not a particularly good or descriptive name for the stuff and something like "smooth tension" would be much more insightful. So the words are important for illuminating the concepts.

Edited by Startraveler

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This is probably true. What it means is that the individual falling into the hole would, had he a window, be able to watch the evolution of the universe occuring outside in extreme, extreme "fast forward" mode. If the black hole was massive enough, the Hawking radiation would evaporate it over a longer time period, meaning that the eyewitness might even be able to witness the end of the universe before he ever hit that event horizon.

The theory clearly states that he would at the very least witness the complete evaporation of the black hole before he ever reached the even horizon, which would itself never actually form anyway.

Harte

Thanks for that comment. That got my brain straightened up. That would be awsome, watching a black hole evaporate so quickly. But the question i have is this. Is there any observations that tell us how fact the matter is falling into the black hole? Because it hink i have a dilemna. If the matter falling into the black hole falls in quickyl from our perspective, it means that by the time the object in question gets into the black hole BEFORE it evaporates. So then the question of how time runs in the and around the black hole must be questioned.

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Thanks for that comment. That got my brain straightened up. That would be awsome, watching a black hole evaporate so quickly. But the question i have is this. Is there any observations that tell us how fact the matter is falling into the black hole? Because it hink i have a dilemna. If the matter falling into the black hole falls in quickyl from our perspective, it means that by the time the object in question gets into the black hole BEFORE it evaporates. So then the question of how time runs in the and around the black hole must be questioned.

The problem is that we have not observed a black hole long enough to give us a real idea of the time sequences. We can, more or less explain what is happening there. Maybe even why it is happening but we could not say much more at this time.

Besides, we would have to know what type of black hole we are talking about. The physics of a rotating, charged, black hole is a little different from the uncharged (static or non-rotating) one.

If you really want to get int this all I can really do is give you a list of books to find in your library:

Popular books:

Melia, Fulvio (2003). The Edge of Infinity. Supermassive Black Holes in the Universe. Cambridge U Press. ISBN 978-0-521-81405-8.

Pickover, Clifford (1998). Black Holes: A Traveler's Guide. Wiley, John & Sons, Inc. ISBN 0-471-19704-1.

Thorne, Kip S. (1994). Black Holes and Time Warps. Norton, W. W. & Company, Inc. ISBN 0-393-31276-3.

Hawking, Stephen (1998). A Brief History of Time. Bantam Books, Inc. ISBN 0-553-38016-8.

Melia, Fulvio (2003). The Black Hole at the Center of Our Galaxy. Princeton U Press. ISBN 978-0-691-09505-9.

If you want to get deeper in I can also get you a list of university level books.

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Yes, in my opinion, black holes definitely do exist.

linked-image

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It would be like pouring water into a glass that has no bottom.

Does that mean that there are separate gravity forces that lead, because everything is controlled on earth by gravity from the Twin Towers to obesity.

Somebody said that 'black holes are giant hurricanes.' Very apt descriprion. And further back, somebody else said that all of the planets and rocks and ice orbiting in our solar system came from the sun, not by a supernova, but by the opposing actions of a travelling black hole through the universe. That makes this solar system much older than is viewed.

The sun does not radiate any of its force, in fact we just get small blowoffs from it. The sun is so intense that even the slightest moment of of the energy from the sun would consume anything; so, there must be differing directions of gravitational force.

Black Holes may be the spots on the sun if you think that the univese is one gigantic sun. We on this earth are affetcted by sun spots; our weather, communication, etc.

There is a saying; 'Where the body is, there the eagles will be gathered.'

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Does that mean that there are separate gravity forces that lead, because everything is controlled on earth by gravity from the Twin Towers to obesity.

Somebody said that 'black holes are giant hurricanes.' Very apt descriprion. And further back, somebody else said that all of the planets and rocks and ice orbiting in our solar system came from the sun, not by a supernova, but by the opposing actions of a travelling black hole through the universe. That makes this solar system much older than is viewed.

The sun does not radiate any of its force, in fact we just get small blowoffs from it. The sun is so intense that even the slightest moment of of the energy from the sun would consume anything; so, there must be differing directions of gravitational force.

Black Holes may be the spots on the sun if you think that the univese is one gigantic sun. We on this earth are affetcted by sun spots; our weather, communication, etc.

There is a saying; 'Where the body is, there the eagles will be gathered.'

There are several useful theories, and I believe that the predominant one (hey, can't remember it all) is that black holes are cause by a collapsed sun that attracted its complete solar system in a very small spot causing a center of immense gravity. This gravity keeps attracting matter, which increases the gravity and therefore attracts more matter...

But better than me trying to remember is you to go to the library. I have posted a list of interesting books a few post further up on this thread.

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"An outside observer will never lose an object down a black hole," Stojkovic said. "If you are sitting outside and throwing something into the black hole, it will never pass over, but will stay outside the event horizon,

………………………………....................................................................

...............................................

At the site of the supermassive black hole at the center of the Milky Way, for example, she says astronomers routinely observe what looks like interstellar material disappearing without a trace.

………………………………....................................................................

................................................

Which ones true ? It cant be both. :huh:

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Posted (edited)

"An outside observer will never lose an object down a black hole," Stojkovic said. "If you are sitting outside and throwing something into the black hole, it will never pass over, but will stay outside the event horizon,

………………………………....................................................................

...............................................

At the site of the supermassive black hole at the center of the Milky Way, for example, she says astronomers routinely observe what looks like interstellar material disappearing without a trace.

………………………………....................................................................

................................................

Which ones true ? It cant be both. :huh:

Why not?

Edited by questionmark

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Why not?

Because they are contradictory statements.

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Because they are contradictory statements.

Does logic have to apply to a space where time and matter get warped?

(Note, this is for the sake of the argument)

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There are several useful theories, and I believe that the predominant one (hey, can't remember it all) is that black holes are cause by a collapsed sun that attracted its complete solar system in a very small spot causing a center of immense gravity. This gravity keeps attracting matter, which increases the gravity and therefore attracts more matter...

But better than me trying to remember is you to go to the library. I have posted a list of interesting books a few post further up on this thread.

Matter caused the gravity. Just had to add that because gravity doesnt pop outa nowere. In which case i dont know how a black hole can transport u to mgical places. Its just like a neutron star (except pimped up to the max), the atoms brake down and all etc. But the most important thing about black holes is time and what state matter sxists within the center.

lol... throwing more questions out there aint i..

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"An outside observer will never lose an object down a black hole," Stojkovic said. "If you are sitting outside and throwing something into the black hole, it will never pass over, but will stay outside the event horizon,

………………………………....................................................................

...............................................

At the site of the supermassive black hole at the center of the Milky Way, for example, she says astronomers routinely observe what looks like interstellar material disappearing without a trace.

………………………………....................................................................

................................................

Which ones true ? It cant be both. :huh:

The first statement is factual. The second statement is a mistatement. No material has ever been obsereved "disappearing" down a black hole. What has been routinely observed is matter being converted into energy as it approaches the event horizon. Large emissions of X-Rays, etc., IOW.

Harte

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The first statement is factual. The second statement is a mistatement. No material has ever been obsereved "disappearing" down a black hole. What has been routinely observed is matter being converted into energy as it approaches the event horizon. Large emissions of X-Rays, etc., IOW.

Harte

Hey I wanted them to brood a little over the problem.

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