Slashdot Mirror
Black Holes Disputed
JScarpace writes: "Researchers at the Los Alamos National Laboratory in New Mexico and at the University of South Carolina in Columbia have proposed the existence of "gravastars" which are bubbles of superdense matter. If they are correct, the idea of a black hole with a singularity at the center may be just a fantasy."
Where do all my left socks go from the dryer?
From the outside, these objetcs would look exactly the same as the black holes that most astrophysicists currently believe in. The only difference is that there's no actual hole in the center, just a very dense lump of matter. If you got sucked into one, you'd be spread out over its surface, not stretched into a long string.
If this turns out to be true, the discovery will also cast a shadow of doubt over the big bang theory which also features a singularity.
So when did Alex Chiu get hired at Los Alamos? What with his revolutionary understanding of gravity, energy and the universe.
"I would say that 99 per cent of what my father has written about his own life is false." - L. Ron Hubbard Jr.
http://slashdot.org/comments.pl?sid=26315&cid=2850 660&pid=2850660&startat=&threshold=-1&mode=nested& commentsort=0&op=Change
4 pages in your choice of formats here.
And I thought traditional black holes were wacky enough. According to this, it's possible that our entire universe is contained within one of these gravastars.
I've never heard of this site, but I must admit that was an extremely well-written article; they shoved a lot of physics in it but maintained a really high level of clarity (though it seems to based on a New Scientist article, so they may have just lifted passages from there).
A "singularity" is a point at which the gravitational force is infinite. This logically doesn't even make sense, so it's no wonder that it's disputed.
Cryptnotic
My other first post is car post.
New Theories Dispute the Existence of Black Holes
January 17, 2002 08:00 CDT
Two U.S. scientists have questioned the existence of black holes and suggested, in their place, the existence of an exotic bubble of superdense matter, an object they call a gravastar. The two are pointing out that physicists have swept some "humiliating" problems with black holes under the carpet. By confronting these problems, they claim to have found an alternative fate for a collapsing star.
Emil Mottola of the Los Alamos National Laboratory in New Mexico and Pawel Mazur of the University of South Carolina in Columbia think gravastars are cold, dense shells supported by a springy, weird space inside. They'd look like black holes, lit only by the material raining down onto them from outside. In fact, they seem to fit all the observational evidence for the existence of black holes.
So far, however, physicists have mixed feelings about the idea of gravastars. Their verdicts range from "outstandingly brilliant" to "unlikely." What's certain is that gravastars will rekindle a great debate of the early 20th century: are black holes fact or fantasy?
The idea of black holes dates back to the First World War, when German astronomer Karl Schwarzschild solved the equations of Einstein's newborn theory of gravity while serving on the Russian front. He showed that space-time around any massive star would be curved. Squeeze a large enough star into a tiny enough space and its density would become infinite and the curvature of space-time would spiral out of control. The gravity near one of these objects would be so strong that nothing -- not even photons -- could escape its grasp.
Einstein shared the view of most physicists of that time that such objects, later dubbed black holes, were too outrageous to exist. He argued that it was all academic anyway, since stars never shrink this small. But scientists gradually became convinced that they do. If a star is very massive, it will blast apart in a supernova explosion at the end of its life; and if a core twice as heavy as the Sun remains, no known force can prevent gravity squeezing it to a point.
The result is a "singularity" with infinite density, where the known laws of physics break down. The singularity's gravity would be so powerful it would be cloaked in an "event horizon", a boundary beyond which matter or light couldn't escape.
The dramatic idea of a black hole, which would rip to shreds anyone caught inside it, fired the imaginations of scientists, artists and writers alike. But no one has ever rooted the drama in fact.
"So far, there is no direct observational evidence to show that any of the things astronomers call black holes have event horizons or central singularities," says Neil Cornish, an astrophysicist at the University of Montana in Bozeman.
We know there are compact objects millions of times as heavy as the Sun that hog the centers of galaxies. These black hole candidates give themselves away because hot stars, gas and dust spiraling toward them emit bright X-rays. But that doesn't mean there's a cataclysmic black hole in the vicinity; it could simply be a very massive object. The debate petered out decades ago but there's still no ironclad proof that black holes exist.
There are enough problems in black-hole theory itself to make their existence seem implausible to say the least. These problems stem from the fact that our Universe is actually very different from the one that Schwarzschild considered. If we're to produce a proper description of the Universe we live in, Einstein's classical theories need to be meshed together with what we know about the quantum laws governing the behavior of fundamental particles and fields.
Mazur and Mottola have been thinking about quantum gravity for nearly a decade. They began by examining the nature of "quantum fluctuations" in space, time and even in energy fields. Empty space, for example, is never really empty.
On the tiniest scales, little particles are popping in and out of existence all the time, creating a seething, fluctuating fluid. "Like a fish in a calm pond, who is not aware of all the incessant jiggling of the water molecules, we are usually not aware of the quantum medium we are immersed in," Mottola said.
And they have found that quantum fluctuations in the electromagnetic fields that describe tiny things like photons can influence gravitational phenomena on the large scale-such as black holes. So, they reasoned, when early black hole theorists ignored quantum effects they were creating an unreal space-time.
This traditional approach to black holes has produced strange anomalies anyway, and these have remained unresolved, Mazur and Mottola claim. There are problems, for instance, with a black hole's entropy -- a measure of the amount of information it holds. An object that contains many possible states has high entropy, in the same way that a computer with more bits of memory can store more information.
When a star forms a black hole, all the unique information about the star -- its chemical composition, for instance -- appears to be squashed out of existence. Yet current theory suggests black holes have enormous entropy -- a billion, billion times that of the star that formed them. No one can fathom where all this extra entropy comes from or where it resides. "Where are all these zillions of states hiding in a black hole?" says Mottola. "It is quite literally incomprehensible."
Another seemingly impossible feature is that photons falling into a black hole would gain an infinite amount of energy by the time they reach the event horizon. But the gravitational effects of this enormous energy are ignored in the classical theory. Mottola says these problems have forced physicists to dream up far-fetched excuses. They say, for example, that some of the black hole's entropy might be hidden in other universes.
Mottola doesn't buy these "esoteric assumptions" and concludes that black holes are a bag of contradictions that don't make a good case for their own existence at all.
But is there an alternative? Could it be that when a star collapses, something happens to prevent a black hole forming? Mazur and Mottola think so. They have shown that quantum effects can make space-time change into a new and curious state that would lead to the formation of a strange new object.
That change is a phase transition, like liquid water turning into a solid block of ice. They believe that in the extreme conditions of a collapsing star, space-time undergoes a quantum version of a phase transition. The phenomenon is nothing new. The Nobel Prize for Physics in 2001 was awarded for the observation of just such an event in the lab: the transformation of a cloud of atoms into one huge "super-atom," a Bose-Einstein Condensate (BEC). This clump of atoms, which all share the same quantum state, forms at temperatures within a whisker of absolute zero.
When an event horizon is about to form around a collapsing star, Mazur and Mottola believe that the huge gravitational field distorts the quantum fluctuations in space-time. These fluctuations would become so huge they would trigger a radical change in space-time, very similar to the formation of a BEC.
This would create a condensate bubble. It would be surrounded by a thin spherical shell composed of gravitational energy, a kind of stationary shock wave in space-time sitting exactly where the event horizon of a black hole would traditionally be. The formation of this condensate would radically alter the space-time inside the shell.
According to Mazur and Mottola's calculations, it would exert an outward pressure. Because of this, infalling matter inside the shell would do a U-turn and head back out to the shell, while matter outside the shell would still rain down on it.
In a paper submitted to Physical Review Letters, Mazur and Mottola have shown that, like classical black holes, gravastars are a stable solution of Einstein's equations. What's exciting, they say, is that gravastars don't suffer any of the mathematical ailments of black holes.
There's no riotous singularity where the laws of physics break down. There's no event horizon to imprison light and matter. And the entropy of a gravastar would be much lower than that of any star that might collapse to form it, dodging the problem of excessive entropy that plagues black holes.
Take a gravastar with a mass 50 times that of the Sun, for example. Like the event horizon of a black hole with the same mass, the shell would be roughly 300 kilometers in diameter. But it would be around just 10-35 meters thick. Just a teaspoonful of the material would weigh about 100 million tons. But Mazur and Mottola have shown it would have a temperature of only about 10 billionths of a degree above absolute zero. And it wouldn't emit any radiation, making it as black as any black hole would be.
Gravastars would be just as much fun for sci-fi buffs -- in fact, they'd be even more ruthless. Imagine a black hole of a million solar masses, like the one thought to sit in the center of our Galaxy. You could cross its event horizon without feeling a thing: it's only as you approached the singularity that you'd be torn apart by the huge gravity gradient. But if you were drifting toward a gravastar of the same size, you'd never get anywhere near its center. As soon as you hit the shell you'd explode into pure gravitational energy.
Marek Abramowicz, an expert on black holes at Gothenburg University in Sweden, calls the idea of gravastars "outstandingly brilliant. Their unique and remarkable properties could explain several high-energy astrophysical phenomena that now are puzzling." He thinks they might explain gamma-ray bursts -- ultra-intense flashes of gamma radiation from a distant source that appear somewhere in the sky about once a day.
Astronomers aren't certain what causes gamma-ray bursts. It might be the formation of a black hole in a supernova explosion, but this process would struggle to muster enough energy. The birth of a gravastar, on the other hand, would be extraordinarily violent and might shed enough energy to account for gamma-ray bursts.
Mottola points to another possible connection between gravastars and astronomical observations. Three years ago, data from distant stellar explosions suggested that the expansion of the Universe is getting faster all the time (New Scientist, 11 April 1998, p 26). Many physicists ascribe this acceleration to a mysterious "dark energy" that gives space an outward pressure.
Mottola says that if you scale the size of a gravastar up to around the size of the visible Universe, the pressure of the vacuum inside roughly matches the pressure that seems to be accelerating the expansion of the Universe. So our Universe might be one big cosmic gravastar: a giant shell trapping the Milky Way and all the other galaxies we see. "We might be able to entertain the really radical notion that we -- and everything we see in the Universe -- could be inside such an object," Mottola speculates.
It's a bold claim, and he and Mazur are still working out whether it's justifiable. Unlike their hypothetical gravastar, the Universe contains copious ordinary matter and its visible edge is always ballooning outward. But they're keen to see what happens when they modify their gravastar model to include these complications. "It is certainly premature at this point, but the seeds of a possible new cosmological model are contained in the gravastar solution," says Mottola.
In the meantime, they are trying to figure out how they could tell ordinary-sized black holes and gravastars apart. The differences might be subtle -- after all, in isolation, they're both dark and the gravitational fields outside a black hole event horizon and the gravastar shell would be the same. But a good guess would be that gravastars would shine more brightly, since matter falling onto one would be turned into radiation. Black holes would gobble all the matter, but a gravastar would let its energy escape.
The next step is to identify the telltale signs of a gravastar, Mottola said. "It is the only way to convince the skeptical-including ourselves-that nature really behaves this way." Yet physicists aren't even sure what black holes look like.
In October last year, they reported seeing what appeared to be a heavyweight black hole, but material falling onto it is emitting far brighter X-rays than theories predict. The excess energy is roughly equivalent to the output of 10 billion Suns. If it is a black hole, it's not clear why it's so bright.
The object may be whirling round and dragging magnetic fields at the event horizon with it, and these could generate the extra energy by whipping up and heating nearby gases. But Mazur thinks there's a better explanation for that extra energy. The "black hole" could be a gravastar, he says. Stars, gas and dust raining down onto its shell would violently dissolve into pure gravitational energy that might emerge as bright X-rays.
To try to resolve this issue, Mazur is working out what a rotating gravastar might look like. Like every other compact object in the Universe, a gravastar would almost certainly be spinning rapidly.
Not all astronomers are as enthusiastic about gravastars. Cornish questions whether an exploding star could really lose enough entropy to form a gravastar, given that the second law of thermodynamics says that the entropy of an isolated object will always tend to increase.
"In other words, a cup can break into a thousand pieces, but it is highly unlikely that a thousand shards of pottery will spontaneously come together to form a cup," says Cornish. "Mazur and Mottola talk about a star shedding entropy in some way to make the formation of a gravastar possible, but I don't think that is a likely scenario." But Mottola points out that when exploding stars form other remnants, such as neutron stars, they do shed entropy.
And although Cornish admits that black hole singularities are mathematically troublesome, he also believes that a satisfactory quantum theory of gravity will cure this problem. Then there'll be no need for gravastars, he says. Robert Wald of Chicago University adds that Mottola and Mazur have put forward no arguments about how gravastars could form in the devastating collapse of a massive star.
Even if they did form, how would they survive the onslaught of matter raining down on them? "What happens if a gravastar has accreting matter showered upon it? Won't it collapse to a black hole?" he says.
"The gravastar is stable," counters Mottola. He says that matter falling onto the shell could make it wiggle and radiate away energy, but because the gravitational pull of the shell balances the force of the springy vacuum inside, it couldn't actually collapse. Any matter that fell onto the shell would simply become part of it, he says.
All the same, Mottola and Mazur admit there are still unsolved issues with the formation of gravastars. "We must have a better idea of how this phase transition actually occurs in the gravitational collapse process," says Mottola.
The exact nature of the exotic stuff inside the gravastar shell is still open to debate, and they hope to find out whether gravastars can really form in the mayhem of a star's violent death -- and whether gravastars could merge to form the heavyweight objects that sit at the center of galaxies. They are encouraging others to join the investigation. "There are many unanswered questions and we are really just opening a new direction for future research," says Mottola.
But if gravastars can weather the controversy, then maybe there'll no longer be any need for black holes -- maybe they really are pure fantasy. It wouldn't be the first time that Einstein's dazzling intuition has been proved correct.
Source: New Scientist
Cosmiverse Staff Writer
What I do find interesting is that this gravastar model, like the black hole model, implies that the universe and black holes/gravastars are similar in nature: that they belong to the same class of objects. It is a wonderful puzzle to look into a black hole wondering "what's IN there", when the answer might be something that has qualities similar to the life-cycle of our own cosmos.
Until we get some solid predictions about ways to differentiate one from the other, this is going to be a purely theoretical debate. Hopefully someone can advance the debate into the experimental realm soon. Maybe the new gravitational observatories can "shed some light" on this shadowy subject. ;)
I've got a bad attitude and karma to burn. Go ahead. Mod me down.
Study of cash flowing into one particularly superdense gravistar rumoured to exist in a town called Redmond, Washington
-- In the beginning was the WORD, and the WORD was UNSIGNED, and the main(){} was without form and void...
And now every single Linux user on the planet will chime in with their own expert opinion on this topic. This opinion will most likely be based on a quick glance through of the article, because a deeper reading would require knowledge which is not fathomable to the vast majority of the Slashdot community.
That's right everyone, jump in with your own little additions to the story. Try to make everyone think you are smart. Make valiant efforts to convince others that you are learned and already aware of what this new science holds for the future. Pretend that when people read your nonsense that you are placed in higher esteem.
Don't forget to moderate me into oblivion, you fools who refuse to hear any speech that does not praise the wonder of Linux.
Big Loader, load'n 'em up and truck'n 'em out for almost 4 years now.
bigspender540@hotmail.com
I suppose it would make things a bit easier to understand, more like a lava lamp instead of a big flat bath tub with many, many drains.
Job? I don't have time to get a job! Who will sit around and bitch about being broke and unemployed then?
Is it just me, or does anybody else think that gravastar is one of the silliest sounding names they've ever heard? What success will a theory of gravastars have in the popular press when we have things like wormholes, quasars, pulsars, brown dwarfs, and super-massive black holes? Gravastar sounds like something out of one of the poorer Buck Rogers. Yeah, I know we're talking science and not popular science, but still, there is a long tradition of coming up with interesting names for interesting phenomena (like quark).
A black hole is just a place where the escape velocity exceed the speed of light.
There is no dispute over whatever such a thing can actually exist, as all you need is enough mass for it to happen.
The question if a black hole has a singularity is what is being disputed here.
I don't see why it matters that much, theoretically, there isn't even time inside a black hole, since the gravity is greater than C.
There isn't a way for a singularity to be formed.
--
Two witches watched two watches.
Which witch watched which watch?
That's more of a pinkish-red hole, isn't it?
The fact that it is a black hole doesn't automagically make it a super-dense singularity. I, too, have a black hole, however mine expels matter instead of sucking it up.
Quite a sight, I might add. If there is enough interest I might even post a video.
What do you say?
Big Big Loader!!!
bigspender540@hotmail.com
"God made us live inside a gravastar! When we die we'll turn into gravitational energy and pass through the cell straight to heaven that's just outside".
Two U.S. scientists have questioned the existence of black holes both seem to be superdense not that this matters. The theroy is currently only supported by a springy, weird space the pair cannot explain. So far, however, physicists have mixed feelings about the idea of gravastars. Their verdicts range from "outstandingly brilliant" to "unlikely." as we can see this 'outstandingly brilliant' is obviously 'unlikely' due to the fact that The gravity near one of these objects would be so strong that nothing -- not even photons [light] -- could escape its grasp. However, The exact nature of the exotic stuff inside the gravastar shell is still open to debate, as any man and his dog's guess can be supported maybe there'll no longer be any need for black holes -- maybe they really are pure fantasy. To the dismay of Sci Fi writers arround the globe.
Source: Old Scientist
What are they going to do now that singularities do not exist! Well, I guess they'll still have tachyons to play with. And caves. One should never forget the caves. Why the fuck did every second Voyager episode have to be in caves?!
Ok, my physics is a little rusty but.. this doesn't make sense.
As the article mentions - you just CANT go around violating the second law of thermodynamics like they do (i.e. for a gravstar to form it must 'lose' entropy).
According to these guys the spherical outer shell (a standing gravitational wave) would balance out with the incoming matter. Now waiiit just a minute. Eventually the matter on the shell would exceed the force of the inner substance supporting it - then what do you have? They say that it would cause the sphere to wiggle and radiate away energy - well every struture has it's limits, what would happen when, say, a more massive gravstar impacts a less massive gravstar? Or two gravstars of equal mass impact each other?
Just b/c our understanding of physics breaks down at the singularity doesn't mean it does not exist (remember we can't describe in physical terms just what the first few picoseconds of the big bang where like - the physics just can't cope with the amount of matter/energy involved).
Now, we can *never* actually observe a black hole (God Abhors a Naked Singularity) which doesn't mean they don't exist.
"infalling matter inside the shell would do a U-turn and head back out to the shell, while matter outside the shell would still rain down on it." TO do so the matter woudl have to exceed the speed of light. Right.
Occam's Razor -- These guys say that there are a lot of discrepancies in the Black Hole theory that are unanswered, and provide alternate explanations. There are some problems with their own theory --
...whether an exploding star could really lose enough entropy to form a gravastar, given that the second law of thermodynamics says that the entropy of an isolated object will always tend to increase.
That point in itself would be against the gravistar theory. Because, they themselves have admitted that there have been mathematical shortcomings. The implication of this is that quantum behaviour _can_ stabilise, in which case, we would have had BEC occuring naturally, which is not the case.
"The gravastar is stable," counters Mottola. He says that matter falling onto the shell could make it wiggle and radiate away energy, but because the gravitational pull of the shell balances the force of the springy vacuum inside, it couldn't actually collapse. Any matter that fell onto the shell would simply become part of it, he says.
It is easier to accept the Black Hole theory. Just consider the Chandrashekar limit for example - if you are withing range, you are absorbed, else you are pulled closer. And since photons themselves have been proved to be absorbed by these, there is evidence of even horizon. But in this, we would be having an evergrowing event horizon. Given the age of the universe, if the horizon _does_ grow, just imagine for a moment what this means. Heck, there would absolutely no chance of survival for giant stars, which is not the case. Agreed, could be anamolies, but nevertheless worth a thought, right?
IMHO, as someone with experience in particle physics (I've worked on SQUIDS), I feel that this theory has a lot of points which need to be ironed out.
... does anyone know which issue of PRL this article is supposed to appear in? I'm working on a paper surveying the state of black hole theory, and it'd be kinda nice to include a good reference :)
:)
I'll say more after I've had a chance to read it carefully... Gonna have to track down a copy of Weinberg to follow the research article, by the looks of it
In Soviet Russia, sig types you!
SEATTLE - Bill Gates, richest man in the world, announced late Friday evening, that in keeping with his company's new policy of "Discover Your World" he would be putting 30 billion dollars into funding a trip to the far reaches of outer space to finally put an answer to the question, " What is a black hole?"
"We must strive to stretch our horizons" Mr. Gates said while unveiling a mock up spacecraft. "The Qube is singularly revolutionary - it is controlled via neural networks which interface between the ship with these nifty lasers that go over one eye."
However skeptics maintain that information will not be able to travel back from the ship even if it does collect scientific data about the nature of black holes. Microsoft, however, seems unfazed; "We realize at the current time, that issue may cause us problems, though we aren't worried - we work best under deadlines - take our release of windows 97 . . . well that's a bad example, umm. . . Microsoft has a great team that helps us get out of tight situations - take the DOJ trials - no one expected us to come out of that scot-free."
Top Enron executives also expressed interest in coming along for the trip, and plan on funding their portion selling Enron Ethics Handbooks on Ebay , with a source close to the vice president mentioning that "Anyplace would be better than here when our employees find us." - a view shared by Garth Wayne Johnson, Ken Lay's future cellmate in New York's "Ban Gurahz" prison, "Ah no dat da eron beetches ah gonna be ah hoes, so dey nee' packtis an' shit!"
The universe is expanding yes? What is it expanding into?
1q2w3e4r5t6y7u8i9o0pqawsedrftgthyjukilo;p'azsxdcf
Fuck. It's redmond, isn't it? Shoulda caught that.
These problems stem from the fact that our Universe is actually very different from the one that Schwarzschild considered. If we're to produce a proper description of the Universe we live in, Einstein's classical theories need to be meshed together with what we know about the quantum laws governing the behavior of fundamental particles and fields.
Ofcourse. And that is what the Unified Field Theory is all about. In fact, if only gravitons could be proved to exist, then there is a very high probability of the existence of the UFT. In fact, there are just 6 universal constants which need to be meshed in with their corresponding DEs to get the UFT up and running. Which, I'd say, seems simpler than what these guys may have to offer. Are these guys trying imply that UFT does not exist?
They believe that in the extreme conditions of a collapsing star, space-time undergoes a quantum version of a phase transition. The phenomenon is nothing new. The Nobel Prize for Physics in 2001 was awarded for the observation of just such an event in the lab: the transformation of a cloud of atoms into one huge "super-atom," a Bose-Einstein Condensate (BEC). This clump of atoms, which all share the same quantum state, forms at temperatures within a whisker of absolute zero.
In this context, are these people trying to say that the gravistar behaves as a BEC? That makes it a hell lot more complex because you will need really low temperatures, and adding more particles rushing to you at the speed of light increases the temperature and the entropy, both of which their theory goes against. Also Bosons (which are carrier particles, having an integer spin measured in the units of h-bar) would all possess exactly the same quantum state. So considering the existence of identical entities elsewhere, we could jump to any of these thingys just like that. Or any matter trapped in even one of these, could be spread across multiple copies of these entities.
The implications are really wierd, I somehow feel that Black Hole theories were a lot more plausible.
The reason wasn't that I'm particulary skeptical about black hole theory, but that I figured I really didn't need to assume anything about it, as long as all the other assumptions I make hold (which they won't, but that's an entirely different matter :-) ). The central engine of quasars can be whatever it likes... :-)
My knee-jerk reaction to the article posted was that it seems like the gravastar isn't allowed to grow, and it has to grow, right? However, skimming the researcher's preprint, it seems like they are addressing the issue, so it is probably just something I've missed. Besides, there'll be enough knee-jerk postings here... :-)
Employee of Inrupt, Project Release Manager and Community Manager for Solid
Well, not quite: but the fact is that with the current model of physics, a black
hole has a singularity in it.
That doesn't make sense. All mass compressed to an infinitesimallay small point, yet with a finite mass?
That means infinite density. When infinities show up, it's a sign that something is wrong with our physics - the opposite would be too unreasonable.
what a primative concept of the universe. for this to even work we'd have to throw out the entire concept of 4th dimensional space/time which one can actually observe with a simple experiment.
Such theories of "gravistars" went out with the old ideas that water, rock, air, and fire made up all matter. Feh.
So hawking radiation doesn't exist? Someone call stephen and make him return that nobel prize. Oh and make him rectify those billions and billions of copies of "a brief history of time".
It's not as if it needs another one, is it? (-:
On a more serious note, the theory will simply get re-engineered and tweaked and plastered over until a new unproveable conjecture happens along. But it must be one which doesn't smack of Young Earth Creationism, or otherwise - as Richard Lewontin wrote - ``allow a Divine Foot in the door''.
My guess is: when the time comes to admit that the new idea is much sexier (it does have a springy foundation, after all), the small differences between a Cosmic Egg and a First Cosmic Balloon won't get anyone but theorists too excited.
If it involves balloons, though, MacDonalds will want it attributed to Ronald.
Got time? Spend some of it coding or testing
Blackholes? Blackhole? We need no stinking blackholes.
:)
Carbon based humanoid in training.
>Anyone see the problem with that? The first
>problem is that no reason is given for the
>airstream over the top to have to meet up
>with the airstreem under the bottom. Why
>can't it just flow straight back?
See here for one of many explanations of the Kutta condition, one of the foundational principles of aerodynamics. This has nothing to do with an explanation for the layman. Basically, it states that the air MUST meet smoothly at the back of the wing.
Logically, if you spend some time thinking about the flow, you cannot possibly construct a situation where the air above the wing somehow slips past the air below. Remember that a jet moves so fast that its wing is only passing through a portion of the air for fractions of a second - it's simply not possible to make the air move fast enough to slip like this.
This principle has been demonstrated NUMEROUS times. You can demonstrate it very easily with a line of smoke through which a wing passes, among a zillion other simple experiments.
--Brandon / Split Infinity Music
Hm. A friend of mine and I have been discussing this one for awhile now.
If by this they mean that vacuum is never really empty because there are usually residual E-M fields lying about, then fine.
If by this comment they're referring to zero point fluctuations, then they are just as guilty of doing bad science as the people that are sweeping whatever problems there are with black holes under the rug in the form of multiple universes and other such ideas. Why?
Well, the idea (as I understand it, I take quantum field theory next semester) that there are zero point fluctuations in the vaccum comes from taking a series approximation. This is a math trick. They then take terms of this series and based upon them come up with particles being created and then destroyed in a vacuum state. But it's a just a math trick used to get an answer! It says nothing about the reality of the system in question, it just helps you get a number.
Many scientists point to things like the Lamb Shift and the Casimir effect as being experimental verifications of zpf's. However, the series that they take can be arranged in another form to get radiative reaction, which is a well-understood phenomenon. So, you can arrange it one way to get "something comes from nothing" or the other way which says "it reacts with its own field." To this date, every zpf calculation that I know of has been done with radiation reaction as well.
Okay, I'm off my soapbox.
Some of the serious expose material should be more than side-splitting enough by itself, however...
I think there'd have to be a Balderdash edition as well, where people put in realistic-sounding explanations that are either total and deliberate frauds and/or proposed by people who really have no idea (like my ex-wide, who asked me (and this is a literal quote) ``I've always wondered, how do they get the batteries into battery chickens?'').
Dawkin's weasel would have to feature in the Balderdash book, together with Haeckel's ontogeny recapitulating phylogeny and that wonderful theory of electricity involving different coloured electricity for the different colours of traffic lights and so on.
Got time? Spend some of it coding or testing
from the University of South Carolina in Columbia:
World declared flat, not round as previously theorized. Oh, and the Earth is at the center of the universe, too.
--
Spaz!
"...gravastars are cold, dense shells supported by a springy, weird space inside."
Black holes are really Moon Pies?
there is one thing i don't quite get in the article. according to quantum theory a vacuum has energy, due to heisenberg's uncertainty principle and minimum energy constraints. check. that is supposed to account for the cosmological that is apparently needed for the universe to be accelerating. however, the figures we get with TRADITIONAL quantum physics is about 120 orders of magnitude greater. adding in string theory, we get 60 orders of magnitude greater (the correction due to the pairing of bosons and fermions). check....
but they are saying that the vacuum energy of the inside of the gravistar would match that of the meaasured universe (for a large universe sized gravistar) THAT MAKES NO SINCE! WHAT then is inside the gravistar. something that has much lower energy (60 magnitudes worth) than even vacuum. they can't even figure out how much vacuum energy the universe has, let alone a gravistar in some odd BEC quantum state.
it seems that by the time they get to that point in the article, they are on the edge of fantasy.
QED
BSD is for people who love UNIX. Linux is for those who hate Microsoft.
Hey, it even says so, in bold: Stating that the fluid flowing above the airfoil is accelerated with respect to the fluid flowing below it ``because it must travel for a longer route in the same time'' is then definitely wrong. Betrayed but your own reference texts, eh?
As harlows_monkey says, in order to understand why the streams do meet if there is a correct angle of attack, you do need deeper insight into aerodynamics than is spelled out in the simple "lay-man's" explanation.
Say no to software patents.
Having studied basic fluid mechanics, I think the two explanations, via vortices and speed differences, are essentially equivalent. A vortex flow around the wing is equivalent to the velocity difference that is the usual explanation. If you compute the force either via the vortex effect, or via the pressure difference, you should get the same answer. The vortex approach is more sophisticated, so it is almost always the other explanation that is given to laymen.
--
The Cap is nigh. Time to get a fresh new account.
How does the recent observation of quantum gravity effects change the model of either singularities or "gravistars?"
A famous former surgeon general discovered the first of these monsters a few years ago, and named it drkoop.com (the .com designation is often used to help identify black holes). Then there was altavista.com, webvan.com, and many others.
The escape velocity exceeds the speed of VC money. Since nothing can go faster than VC money...
Enron, by the way, is not a black hole. It's a pulsar -- a dead star that regularly flashes us with reminders that it's dead ("Enron doesn't have any money," "Enron doesn't have any money," Enron doesn't have any money," etc.).
Not true. That would only be true if you were a stationary observer at the horizon, but there aren't any stationary observers at the horizon. Note that the amount of blueshift depends on who's doing the observing. A freely falling observer doesn't see a huge blueshift close to the horizon. The fact that stationary observers do observe a large blueshift isn't unique to black holes either: it's just a consequency of the ordinary special-relativistic fact that you can blueshift light as much as you want, just by boosting to a new frame by a velocity sufficiently close to the speed of light.
As for the information loss paradox, yes, it's a problem, but there are many proposed solutions other than "the entropy ends up in other universes". (Though personally, I don't find that as farfetched as it sounds, given what quantum gravity already has to say about singularities.)
So they've shown a new solution to Einstein's equations. So what? You can write down all kinds of wacky but valid solutions: warp drives, wormholes, closed timelike loops, eternally collapsing universes, etc. etc. The real question is whether these things can actually form. If you study the dynamics of a collapsing star, there is a lot of evidence that it will lead to a black hole. Regardless of whether gravastars are allowed solutions of the equations, you've got to show that there's some plausible process by which one can actually form. I've read the paper, and I haven't seen any argument that convinces me. Apparently Wald agrees.
So the stae of matter below the horizon has NOTHING to do with properties of the such a compact object above it. This is because of causality - there is no information flow from behind the horizon..
<^>_<(ô ô)>_<^>
Why is Occam's Razor is always invoked in these arguments , does occam's razor always apply , is it always applicable. I am not saying you are wrong , but why is occam invoked.
Feel free to search groups.google.com on the sci.physics* Usenet groups for "Louis Savain" and "Nemesis", for about 6 or 7 years of Savain making an ass out of himself.
Sounds like someone flunked their intro Physics class and refuses to believe it's because they're stupid.
I welcome the gravistar proposal. Since learning of Hawking radition (blackbody radiation with a temperature inversely related to the radius of the event horizon), I have always puzzled over the process of forming the event horizon. A black hole eventually evaporates with a shrinking event horizon. How can a event horizon come into existence without starting from a very small event horizon or point that would release enough Hawking radiation to deplete the black hole?
Modern physics is anything but "voodoo". In fact, the whole point of it is that it is open to independent verification. You don't HAVE to be a "priest" to weigh in. What you DO have to do is put in the intellectual effort to understand what has already been done; learn some math, learn some physics, and nuclear chemistry - then you can examine the evidence for yourself.
Big Bang: take a simple spectrograph and a telescope (e.g. the Mt. Wilson 100-inch, which you can rent time on). Look at a sample of distant galaxies. Measure the wavelength of the hydrogen emission line (which is doppler shifted according to the relative velocity between the telescope and the galaxy); you'll see that the more distant the galaxy is, the faster it is receeding from you. Think about what that implies about the past. Certainly the simplest (if not the only) answer is that in the past the galaxies were closer to each other than they are now - ultimately at some point they would have to come from a single point.
It goes on and on - but the point I'm trying to make is that you shouln't treat modern physics as some kind of revealed religion. Instead, understand the evidence for and against the various theories - but also give the honest effort to learn the tools of modern science (above all math, but also physics, chemistry & astronomy).
If you don't then you're just spouting an uninformed opinion - and there are too many of those on /. already!
Human genome = 3 billion base pairs = 6 GBit. Windows + Office = 20 Gbit. Which is more impressive?
He's a just a Net.Crank, who has no understanding of physics but thinks he knows better than everyone.
I actually think this illustrates his point. As a society, the people who are viewed as most intelligent are the people who come up with theories. I think it is pretty easy to come up with new theories about how the universe works.
But, as you point out, the only thing that really matters is the testing of the theories and the reconciliation of those theories with the experimental results.
In other words, questions about black holes are equivalent to voodoo. We can never test hypotheses about them directly, we are just asked to believe they exist. Of course, that doesn't stop astronomers putting out press releases every year saying that they have found definitive evidence for black holes, but that just means they need new funding.
Scientists theorize that in the event that a particle attains no energy (absolute zero) it would create a black hole. This is a higly complicated idea involving the similarities between absolute (infinate) energy and zero energy (absoulte zero). Here is a good web page involving multiple ideas and mathematics on black holes/gravity ect. http://antwrp.gsfc.nasa.gov/htmltest/rjn_bht.html
I once shot a man who posted too many, "Imagine a beowulf cluster of these"
Nonsense. There are many sciences that are limited in what they are able to "directly test", as opposed to passively observe. Pretty much all of astronomy, cosmology, geology, palentology, the history of evolution of life on our planet, etc. etc. That doesn't make them "voodoo", that doesn't mean you have to take them on faith, and it doesn't mean that theories can't be tested. Black holes have observable consequences, just like the Big Bang does, just like natural selection does, just like any number of geological processes do, and you can test those consequences.
Let's hope their paper doesn't include words like "zillions." Also:
But if gravastars can weather the controversy, then maybe there'll no longer be any need for black holes -- maybe they really are pure fantasy. It wouldn't be the first time that Einstein's dazzling intuition has been proved correct.
It also wouldn't be the first time his dazzling intuition has been proved wrong. Remember, Einstein didn't believe quantum mechanics was possible (at first, anyway).
-Legion
All atoms (and other particals) are moving really fast 0.1 the speed of light. This creates alot of entrophy between particles, so they are not likely to fuse together. When one partical does not move at all, every other local partical (and theortetically every particle in the universe) is attracted to a single point. This minimizes entrophy, thusly maximizing energy ( ant velocity to that point) in all local particles. This theoretically means that local particals will smash into eachother from all angles. Since most velocity vectors will cancel, the new fused partical will also have no kinetic energy. This process will excalate into a full on black hole.
I once shot a man who posted too many, "Imagine a beowulf cluster of these"
According to the article (in gr-qc/0109035, not the horrible thing linked from the /. article above), we essentially have a phase transition that results in an inflationary subspace inside this thin shell! I grant that, for some odd assumptions, this might be a stable solution, but I kind of doubt it. It has been proposed before that the collapse to a singularity triggers internal inflation, which is plausible but still gives a black hole, not a "gravstar".
Anyway, and I quote from their own article, "Here we forgo any discussion of the details of the quantum phase transition and present only the solution of Einstein's eqs." Mazur and Mottola have no clue how to make such a beast, either. If nothing else, the energy density wouldn't approach that needed for a phase transition until long after the entire assemblage was well within its own event horizon, again giving -- you guessed it! -- a Schwartzchild black hole. Recall, when a solid mass reaches the density required to fall within its own event horizon, the total density isn't much above nuclear densitites. During big bang baryosynthesis, densities are easily this large and inflation obviously didn't occur then (or else we'd have no protons in the universe).
Quantum mechanics: the dreams that stuff is made of.
Isn't English wonderfully ambiguous? On Slashdot, we know that the world "free" can take different meanings, which are not at all the same. However, there are other words like this as well: for instance, solid can mean "not liquid or gaseous", but it can also mean "Not hollowed out: a solid block of wood". I obviously meant the latter, as should have been clear by context (solid spheres, vs. hollow spheres as in gravastars). Moreover, in order to make myself clearer, I even put "full" in parenthesis after the words "solid speres".
Say no to software patents.
http://groups.google.com/groups?hl=en&threadm=32bc f39a.1109250487%40news.demon.co.uk&rnum=1&prev=/gr oups%3Fq%3D%2522James%2BCain%2522%2Bphysics%26hl%3 Den
I was in high school at the time, the idea of shells(more than one though) due to increaing size was central to my idea...
So did I understand correctly that an attempt to fly through one of those would result in a severe case of indigestion? Of-course, with me every mission is a suicide mission, but still... Or will my body simply end its normal existence and would be transformed instantly into some amount of gravitational energy and some X-Rays? Then you can call me the X-Ray man!
You can't handle the truth.
I am not suggesting you take them on faith. I am suggesting that you use observations to determine the truth of the hypothesis. I am suggesting that people use a scientific method rather than talk about mindless waffle like this paper. I could write any old piece of junk about what is in the centre of a black hole. The important thing is for me to make predictions about observable effects such as rotation curves, etc..
Well, the color of space, right, your average space color is, well, black.
And the color of a black hole, your average black hole color - they're black.
So how are you supposed to see them then??!
IANAP, but wouldn't one be in dire straits if one were inside stellar mass?
"Beware, I live!"
Sinistar!
<---[singularity sig]
Noo Zeeureees Deespoote-a zee Ixeestence-a ooff Bleck Hules
Junooery 17, 2002 08:00 CDT
Tvu U.S. sceeentists hefe-a qooesshuned zee ixeestence-a ooff bleck hules und sooggested, in zeeur plece-a, zee ixeestence-a ooff un ixuteec boobble-a ooff sooperdense-a metter, un oobject ze
ey cell a grefester. Zee tvu ere-a pueenting oooot thet physeecists hefe-a svept sume-a "hoomeelieting" prublems veet bleck hules under zee cerpet. By cunffrunteeng zeese-a prublems, zeey cle
eem tu hefe-a fuoond un elterneteefe-a fete-a fur a cullepseeng ster.
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Imeel Muttula ooff zee Lus Elemus Neshunel Leburetury in Noo Mexeecu und Pevel Mezoor ooff zee Uneefersity ooff Suoot Ceruleena in Culoombeea theenk grefesters ere-a culd, dense-a shells soop
purted by a spreengy, veurd spece-a inseede-a. Zeey'd luuk leeke-a bleck hules, leet oonly by zee metereeel reeening doon oontu zeem frum ooootseede-a. In fect, zeey seem tu feet ell zee oobs
erfeshunel ifeedence-a fur zee ixeestence-a ooff bleck hules.
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Su fer, hooefer, physeecists hefe-a meexed feeleengs ebuoot zee idea ooff grefesters. Zeeur ferdeects runge-a frum "ooootstundeengly breelliunt" tu "unleekely." Vhet's certeeen is thet grefes
ters veell rekeendle-a a greet debete-a ooff zee ierly 20t centoory: ere-a bleck hules fect oor funtesy?
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Zee idea ooff bleck hules detes beck tu zee Furst Vurld Ver, vhee Germun estrunumer Kerl Schverzscheeld sulfed zee iqooeshuns ooff Ieenstein's nooburn zeeury ooff grefeety vheele-a serfeeng o
on zee Roosseeun frunt. He-a shooed thet spece-a-teeme-a eruoond uny messeefe-a ster vuoold be-a coorfed. Sqooeeze-a a lerge-a inuoogh ster intu a teeny inuoogh spece-a und its denseety vuool
d becume-a inffeenite-a und zee coorfetoore-a ooff spece-a-teeme-a vuoold spurel oooot ooff cuntrul. Zee grefeety neer oone-a ooff zeese-a oobjects vuoold be-a su strung thet nutheeng -- nut
ifee phutuns -- cuoold iscepe-a its gresp.
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Ieenstein shered zee feeoo ooff must physeecists ooff thet teeme-a thet sooch oobjects, leter doobbed bleck hules, vere-a tuu ooootregeuoos tu ixeest. He-a ergooed thet it ves ell ecedemeec u
nyvey, seence-a sters nefer shreenk thees smell. Boot sceeentists gredooelly beceme-a cunfeenced thet zeey du. Iff a ster is fery messeefe-a, it veell blest epert in a soopernufa ixpluseeun e
t zee ind ooff its leeffe-a; und iff a cure-a tveece-a es heefy es zee Soon remeeens, nu knoon furce-a cun prefent grefeety sqooeezeeng it tu a pueent.
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Zee resoolt is a "seengoolerity" veet inffeenite-a denseety, vhere-a zee knoon levs ooff physeecs breek doon. Zee seengoolerity's grefeety vuoold be-a su pooerffool it vuoold be-a clueked in
un "ifent hureezun", a buoondery beyund vheech metter oor leeght cuooldn't iscepe-a.
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Zee dremeteec idea ooff a bleck hule-a, vheech vuoold reep tu shreds unyune-a cooght inseede-a it, fured zee imegeeneshuns ooff sceeentists, erteests und vreeters eleeke-a. Boot nu oone-a hes
ifer ruuted zee drema in fect.
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"Su fer, zeere-a is nu durect oobserfeshunel ifeedence-a tu shoo thet uny ooff zee theengs estrunumers cell bleck hules hefe-a ifent hureezuns oor centrel seengoolerities," seys Neeel Curnees
h, un estruphyseecist et zee Uneefersity ooff Muntuna in Buzemun.
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Ve-a knoo zeere-a ere-a cumpect oobjects meelliuns ooff teemes es heefy es zee Soon thet hug zee centers ooff gelexeees. Zeese-a bleck hule-a cundeedetes geefe-a zeemselfes evey becoose-
a hut sters, ges und doost spureleeng tooerd zeem imeet breeght X-reys. Boot thet duesn't meun zeere's a ceteclysmeec bleck hule-a in zee feecinity; it cuoold seemply be-a a fery messeefe-a o
object. Zee debete-a petered oooot decedes egu boot zeere's steell nu iruncled pruuff thet bleck hules ixeest.
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Zeere-a ere-a inuoogh prublems in bleck-hule-a zeeury itselff tu meke-a zeeur ixeestence-a seem implooseeble-a tu sey zee leest. Zeese-a prublems stem frum zee fect thet oooor Uneeferse-a is
ectooelly fery deefffferent frum zee oone-a thet Schverzscheeld cunseedered. Iff ve're-a tu prudooce-a a pruper descreepshun ooff zee Uneeferse-a ve-a leefe-a in, Ieenstein's clesseecel zeeur
eees need tu be-a meshed tugezeer veet vhet ve-a knoo ebuoot zee qoountoom levs guferneeng zee behefeeur ooff foondementel perteecles und feeelds.
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Mezoor und Muttula hefe-a beee theenking ebuoot qoountoom grefeety fur neerly a decede-a. Zeey begun by ixemeening zee netoore-a ooff "qoountoom flooctooeshuns" in spece-a, teeme-a und ifee i
n inergy feeelds. Impty spece-a, fur ixemple-a, is nefer reelly impty.
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Oon zee teeniest sceles, leettle-a perteecles ere-a puppeeng in und oooot ooff ixeestence-a ell zee teeme-a, creeteeng a seetheeng, flooctooeteeng flooeed. "Leeke-a a feesh in a celm pund, vh
u is nut evere-a ooff ell zee incessunt jeeggling ooff zee veter mulecooles, ve-a ere-a usooelly nut evere-a ooff zee qoountoom medeeoom ve-a ere-a immersed in," Muttula seeed.
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Und zeey hefe-a fuoond thet qoountoom flooctooeshuns in zee ilectrumegneteec feeelds thet descreebe-a teeny theengs leeke-a phutuns cun infflooence-a grefeeteshunel phenumena oon zee lerge-a
scele-a-sooch es bleck hules. Su, zeey reesuned, vhee ierly bleck hule-a zeeureests ignured qoountoom iffffects zeey vere-a creeteeng un unreel spece-a-teeme-a.
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Thees tredeeshunel eppruech tu bleck hules hes prudooced strunge-a unumeleees unyvey, und zeese-a hefe-a remeeened unresulfed, Mezoor und Muttula cleeem. Zeere-a ere-a prublems, fur instunce-
a, veet a bleck hule's intrupy -- a meesoore-a ooff zee emuoont ooff inffurmeshun it hulds. Un oobject thet cunteeens muny pusseeble-a stetes hes heegh intrupy, in zee seme-a vey thet a cumpo
oter veet mure-a beets ooff memury cun sture-a mure-a inffurmeshun.
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Vhee a ster furms a bleck hule-a, ell zee uneeqooe-a inffurmeshun ebuoot zee ster -- its chemeecel cumpuseeshun, fur instunce-a -- eppeers tu be-a sqooeshed oooot ooff ixeestence-a. Yet coorr
ent zeeury sooggests bleck hules hefe-a inurmuoos intrupy -- a beelliun, beelliun teemes thet ooff zee ster thet furmed zeem. Nu oone-a cun fethum vhere-a ell thees ixtra intrupy cumes frum o
or vhere-a it reseedes. "Vhere-a ere-a ell zeese-a zeelliuns ooff stetes heeding in a bleck hule-a?" seys Muttula. "It is qooeete-a leeterelly incumprehenseeble-a."
Unuzeer seemeengly impusseeble-a feetoore-a is thet phutuns felleeng intu a bleck hule-a vuoold geeen un inffeenite-a emuoont ooff inergy by zee teeme-a zeey reech zee ifent hureezun. Bo
ot zee grefeeteshunel iffffects ooff thees inurmuoos inergy ere-a ignured in zee clesseecel zeeury. Muttula seys zeese-a prublems hefe-a furced physeecists tu dreem up fer-fetched ixcooses. Z
eey sey, fur ixemple-a, thet sume-a ooff zee bleck hule's intrupy meeght be-a heeddee in oozeer uneeferses.
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Muttula duesn't booy zeese-a "isutereec essoompshuns" und cuncloodes thet bleck hules ere-a a beg ooff cuntredeecshuns thet dun't meke-a a guud cese-a fur zeeur oovn ixeestence-a et ell.
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Boot is zeere-a un elterneteefe-a? Cuoold it be-a thet vhee a ster cullepses, sumetheeng heppens tu prefent a bleck hule-a furmeeng? Mezoor und Muttula theenk su. Zeey hefe-a shoon thet qooun
toom iffffects cun meke-a spece-a-teeme-a chunge-a intu a noo und cooreeuoos stete-a thet vuoold leed tu zee furmeshun ooff a strunge-a noo oobject.
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Thet chunge-a is a phese-a trunseeshun, leeke-a leeqooid veter toorneeng intu a suleed bluck ooff ice-a. Zeey beleeefe-a thet in zee ixtreme-a cundeeshuns ooff a cullepseeng ster, spece-a-tee
me-a undergues a qoountoom ferseeun ooff a phese-a trunseeshun. Zee phenumenun is nutheeng noo. Zee Nubel Preeze-a fur Physeecs in 2001 ves everded fur zee oobserfeshun ooff joost sooch un if
ent in zee leb: zee trunsffurmeshun ooff a cluood ooff etums intu oone-a hooge-a "sooper-etum," a Buse-a-Ieenstein Cundensete-a (BEC). Thees cloomp ooff etums, vheech ell shere-a zee seme-a q
oountoom stete-a, furms et temperetoores veethin a vheesker ooff ebsuloote-a zeru.
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Vhee un ifent hureezun is ebuoot tu furm eruoond a cullepseeng ster, Mezoor und Muttula beleeefe-a thet zee hooge-a grefeeteshunel feeeld deesturts zee qoountoom flooctooeshuns in spece-a-tee
me-a. Zeese-a flooctooeshuns vuoold becume-a su hooge-a zeey vuoold treegger a redeecel chunge-a in spece-a-teeme-a, fery seemiler tu zee furmeshun ooff a BEC.
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Thees vuoold creete-a a cundensete-a boobble-a. It vuoold be-a soorruoonded by a theen sphereecel shell cumpused ooff grefeeteshunel inergy, a keend ooff steshunery shuck vefe-a in spece-a-te
eme-a seetting ixectly vhere-a zee ifent hureezun ooff a bleck hule-a vuoold tredeeshunelly be-a. Zee furmeshun ooff thees cundensete-a vuoold redeecelly elter zee spece-a-teeme-a inseede-a z
ee shell.
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Eccurdeeng tu Mezoor und Muttule's celcooleshuns, it vuoold ixert un ooootverd pressoore-a. Becoose-a ooff thees, inffelleeng metter inseede-a zee shell vuoold du a U-toorn und heed beck oooo
t tu zee shell, vheele-a metter ooootseede-a zee shell vuoold steell reeen doon oon it.
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In a peper soobmeetted tu Physeecel Refeeoo Letters, Mezoor und Muttula hefe-a shoon thet, leeke-a clesseecel bleck hules, grefesters ere-a a steble-a sulooshun ooff Ieenstein's iqooeshuns. V
het's ixceeting, zeey sey, is thet grefesters dun't sooffffer uny ooff zee mezeemeteecel eeelments ooff bleck hules.
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Zeere's nu reeutuoos seengoolerity vhere-a zee levs ooff physeecs breek doon. Zeere's nu ifent hureezun tu impreesun leeght und metter. Und zee intrupy ooff a grefester vuoold be-a mooch looe
r thun thet ooff uny ster thet meeght cullepse-a tu furm it, dudgeeng zee prublem ooff ixcesseefe-a intrupy thet plegooes bleck hules.
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Teke-a a grefester veet a mess 50 teemes thet ooff zee Soon, fur ixemple-a. Leeke-a zee ifent hureezun ooff a bleck hule-a veet zee seme-a mess, zee shell vuoold be-a ruooghly 300 keelum
eters in deeemeter. Boot it vuoold be-a eruoond joost 10-35 meters theeck. Joost a teespuunffool ooff zee metereeel vuoold veeegh ebuoot 100 meelliun tuns. Boot Mezoor und Muttula hefe-a shoo
n it vuoold hefe-a a temperetoore-a ooff oonly ebuoot 10 beelliunths ooff a degree-a ebufe-a ebsuloote-a zeru. Und it vuooldn't imeet uny redeeeshun, mekeeng it es bleck es uny bleck hule-a v
uoold be-a.
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Grefesters vuoold be-a joost es mooch foon fur scee-fee booffffs -- in fect, zeey'd be-a ifee mure-a roothless. Imegeene-a a bleck hule-a ooff a meelliun suler messes, leeke-a zee oone-a thuo
oght tu seet in zee center ooff oooor Gelexy. Yuoo cuoold cruss its ifent hureezun veethuoot feeleeng a theeng: it's oonly es yuoo epprueched zee seengoolerity thet yuoo'd be-a turn epert by
zee hooge-a grefeety gredeeent. Boot iff yuoo vere-a dreeffting tooerd a grefester ooff zee seme-a seeze-a, yuoo'd nefer get unyvhere-a neer its center. Es suun es yuoo heet zee shell yuoo'd
ixplude-a intu poore-a grefeeteshunel inergy.
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Merek Ebremooeecz, un ixpert oon bleck hules et Guzeenboorg Uneefersity in Svedee, cells zee idea ooff grefesters "ooootstundeengly breelliunt. Zeeur uneeqooe-a und remerkeble-a pruperteees c
uoold ixpleeen seferel heegh-inergy estruphyseecel phenumena thet noo ere-a poozzleeng." He-a theenks zeey meeght ixpleeen gemma-rey boorsts -- ultra-intense-a fleshes ooff gemma redeeeshun f
rum a deestunt suoorce-a thet eppeer sumoohere-a in zee sky ebuoot oonce-a a dey.
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Estrunumers eren't certeeen vhet cooses gemma-rey boorsts. It meeght be-a zee furmeshun ooff a bleck hule-a in a soopernufa ixpluseeun, boot thees prucess vuoold strooggle-a tu mooster inuoog
h inergy. Zee burt ooff a grefester, oon zee oozeer hund, vuoold be-a ixtreurdeenerily feeulent und meeght shed inuoogh inergy tu eccuoont fur gemma-rey boorsts.
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Muttula pueents tu unuzeer pusseeble-a cunnecshun betveee grefesters und estrunumeecel oobserfeshuns. Three-a yeers egu, deta frum deestunt steller ixpluseeuns sooggested thet zee ixpunseeun
ooff zee Uneeferse-a is getteeng fester ell zee teeme-a (Noo Sceeentist, 11 Epreel 1998, p 26). Muny physeecists escreebe-a thees eccelereshun tu a mystereeuoos "derk inergy" thet geefes spec
e-a un ooootverd pressoore-a.
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Muttula seys thet iff yuoo scele-a zee seeze-a ooff a grefester up tu eruoond zee seeze-a ooff zee feesible-a Uneeferse-a, zee pressoore-a ooff zee fecoooom inseede-a ruooghly metches zee pre
ssoore-a thet seems tu be-a eccelereteeng zee ixpunseeun ooff zee Uneeferse-a. Su oooor Uneeferse-a meeght be-a oone-a beeg cusmeec grefester: a geeunt shell treppeeng zee Meelky Vey und ell
zee oozeer gelexeees ve-a see-a. "Ve-a meeght be-a eble-a tu interteeen zee reelly redeecel nushun thet ve-a -- und iferytheeng ve-a see-a in zee Uneeferse-a -- cuoold be-a inseede-a sooch un
oobject," Muttula specooletes.
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It's a buld cleeem, und he-a und Mezoor ere-a steell vurkeeng oooot vhezeer it's joosteeffieble-a. Unleeke-a zeeur hypuzeeteecel grefester, zee Uneeferse-a cunteeens cupeeuoos oordeenery mett
er und its feesible-a idge-a is elveys belluuneeng ooootverd. Boot zeey're-a keee tu see-a vhet heppens vhee zeey mudeeffy zeeur grefester mudel tu incloode-a zeese-a cumpleeceshuns. "It is c
erteeenly premetoore-a et thees pueent, boot zee seeds ooff a pusseeble-a noo cusmulugeecel mudel ere-a cunteeened in zee grefester sulooshun," seys Muttula.
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In zee meunteeme-a, zeey ere-a tryeeng tu feegoore-a oooot hoo zeey cuoold tell oordeenery-seezed bleck hules und grefesters epert. Zee deefffferences meeght be-a soobtle-a -- effter ell
, in isuleshun, zeey're-a but derk und zee grefeeteshunel feeelds ooootseede-a a bleck hule-a ifent hureezun und zee grefester shell vuoold be-a zee seme-a. Boot a guud gooess vuoold be-a the
t grefesters vuoold sheene-a mure-a breeghtly, seence-a metter felleeng oontu oone-a vuoold be-a toorned intu redeeeshun. Bleck hules vuoold gubble-a ell zee metter, boot a grefester vuoold l
et its inergy iscepe-a.
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Zee next step is tu identeeffy zee telltele-a seegns ooff a grefester, Muttula seeed. "It is zee oonly vey tu cunfeence-a zee skepteecel-incloodeeng oooorselfes-thet netoore-a reelly behefes
thees vey." Yet physeecists eren't ifee soore-a vhet bleck hules luuk leeke-a.
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In Ooctuber lest yeer, zeey repurted seeeeng vhet eppeered tu be-a a heefyveeeght bleck hule-a, boot metereeel felleeng oontu it is imeetting fer breeghter X-reys thun zeeureees predeect. Zee
ixcess inergy is ruooghly iqooeefelent tu zee ooootpoot ooff 10 beelliun Soons. Iff it is a bleck hule-a, it's nut cleer vhy it's su breeght.
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Zee oobject mey be-a vhurleeng ruoond und dreggeeng megneteec feeelds et zee ifent hureezun veet it, und zeese-a cuoold generete-a zee ixtra inergy by vheepping up und heeteeng neerby geses.
Boot Mezoor theenks zeere's a better ixpluneshun fur thet ixtra inergy. Zee "bleck hule-a" cuoold be-a a grefester, he-a seys. Sters, ges und doost reeening doon oontu its shell vuoold feeule
ntly deessulfe-a intu poore-a grefeeteshunel inergy thet meeght imerge-a es breeght X-reys.
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Tu try tu resulfe-a thees issooe-a, Mezoor is vurkeeng oooot vhet a ruteteeng grefester meeght luuk leeke-a. Leeke-a ifery oozeer cumpect oobject in zee Uneeferse-a, a grefester vuoold elmust
certeeenly be-a speenning repeedly.
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Nut ell estrunumers ere-a es inthooseeestic ebuoot grefesters. Curneesh qooesshuns vhezeer un ixpludeeng ster cuoold reelly luse-a inuoogh intrupy tu furm a grefester, geefee thet zee secund
lev ooff zeermudynemeecs seys thet zee intrupy ooff un isuleted oobject veell elveys tend tu increese-a.
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"In oozeer vurds, a coop cun breek intu a thuoosund peeeces, boot it is heeghly unleekely thet a thuoosund sherds ooff puttery veell spuntuneuoosly cume-a tugezeer tu furm a coop," seys Curne
esh. "Mezoor und Muttula telk ebuoot a ster sheddeeng intrupy in sume-a vey tu meke-a zee furmeshun ooff a grefester pusseeble-a, boot I dun't theenk thet is a leekely scenereeu." Boot Muttul
a pueents oooot thet vhee ixpludeeng sters furm oozeer remnunts, sooch es neootrun sters, zeey du shed intrupy.
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Und elthuoogh Curneesh edmeets thet bleck hule-a seengoolerities ere-a mezeemeteecelly truooblesume-a, he-a elsu beleeefes thet a seteesffectury qoountoom zeeury ooff grefeety veell coore-a t
hees prublem. Zeen zeere'll be-a nu need fur grefesters, he-a seys. Rubert Veld ooff Cheecegu Uneefersity edds thet Muttula und Mezoor hefe-a poot furverd nu ergooments ebuoot hoo grefesters
cuoold furm in zee defesteteeng cullepse-a ooff a messeefe-a ster.
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Ifee iff zeey deed furm, hoo vuoold zeey soorfeefe-a zee oonslooght ooff metter reeening doon oon zeem? "Vhet heppens iff a grefester hes eccreteeng metter shooered upun it? Vun't it cul
lepse-a tu a bleck hule-a?" he-a seys.
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"Zee grefester is steble-a," cuoonters Muttula. He-a seys thet metter felleeng oontu zee shell cuoold meke-a it veeggle-a und redeeete-a evey inergy, boot becoose-a zee grefeeteshunel pooll o
off zee shell belunces zee furce-a ooff zee spreengy fecoooom inseede-a, it cuooldn't ectooelly cullepse-a. Uny metter thet fell oontu zee shell vuoold seemply becume-a pert ooff it, he-a sey
s.
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Ell zee seme-a, Muttula und Mezoor edmeet zeere-a ere-a steell unsulfed issooes veet zee furmeshun ooff grefesters. "Ve-a moost hefe-a a better idea ooff hoo thees phese-a trunseeshun ectooel
ly ooccoors in zee grefeeteshunel cullepse-a prucess," seys Muttula.
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Zee ixect netoore-a ooff zee ixuteec stooffff inseede-a zee grefester shell is steell oopee tu debete-a, und zeey hupe-a tu feend oooot vhezeer grefesters cun reelly furm in zee meyhem ooff a
ster's feeulent deet -- und vhezeer grefesters cuoold merge-a tu furm zee heefyveeeght oobjects thet seet et zee center ooff gelexeees. Zeey ere-a incuooregeeng oozeers tu jueen zee infestee
geshun. "Zeere-a ere-a muny ununsvered qooesshuns und ve-a ere-a reelly joost oopeneeng a noo durecshun fur footoore-a reseerch," seys Muttula.
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Boot iff grefesters cun veezeer zee cuntrufersy, zeen meybe-a zeere'll nu lunger be-a uny need fur bleck hules -- meybe-a zeey reelly ere-a poore-a funtesy. It vuooldn't be-a zee furst teeme-
a thet Ieenstein's dezzleeng intooeeshun hes beee prufed currect.
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Suoorce-a: Noo Sceeentist
Cusmeeferse-a Steffff Vreeter
-- La1d, killed by a newt, while helpless.
Hah! Well-picked... but actually, she's skinnier (and always has been) than her less-broken more-honest replacement.
Got time? Spend some of it coding or testing
>What this demonstrates: you don't need to reach escape velocity to get out of a gravity well.
:P
Well, of course not, if you assume infinite energy, which you have done by "Keep supplying enough force to keep the object moving away from earth at 10 miles/hour". In that sentence, you are really saying "provide enough power to counter gravity, whatever the hell it may be".
Escape velocity refers to a ballistic track, that is, one that doesn't have any acceleration other than the initial one. If you want to stop being ballistic, fine. Let's try it without assuming infinite energy, shall we?
A object cannot pass the speed of light because as it gets close to that speed, it takes more and more energy to do the pushing. Look, mass is energy, right? Well, when you accelerate an object, you pump a lot of energy into it. Therefore when you try to accelerate it some more, you're pushing not just the mass, but that energy you've pumped into it as well. This gives an obvious upper limit on how fast you can push it without having infinite energy. Do the math, and you get C in a vaccum. Thus, if we don't assume infinite energy, then we can't go any faster than light in a vaccum. And here's a neat trick: an upper limit on acceleration _also_ exists, because if we get it to a point where we can't push it any faster due to lack of power, then we're not really accelerating it, now are we?
Now, escape velocity of a black hole is higher than the speed of light. Since we don't have infinite energy, we ain't gonna get out ballistically. We also can't provide acceleration to counter gravity forever due to lack of infinite power to do so once we're inside the event horizon. Thus, you're stuck. QED.
In point of fact, you can't provide enough power to counter gravity at all, once you're below the event horizon. Gravity now has a pull that's higher than you can counter without infinite energy. Acceleration has an upper limit too, remember. So you can't even go away from the singularity, much less out. The only possible direction you can move becomes "towards the singularity". In some solutions, this is expressed by eventually solving out as -radius = +time. That is, forward in time becomes equivalent to going towards the singularity. It's a weird solution, but this is a natural consequence of not assuming the impossible.
- Give a man a fire and he's warm for a day, but set him on fire and he's warm for the rest of his life.
The gravity field is still going to pull the atoms in your body that are closer more than those that are further away. So, you still get stretched out in a line...