No Naked Black Holes 317
Science News reports on a paper to be published in Physical Review Letters in which an international team of researchers describes their computer simulation of the most violent collision imaginable: two black holes colliding head-on at nearly light-speed. Even in this extreme scenario, Roger Penrose's weak cosmic censorship hypothesis seems to hold — the resulting black hole (after the gravitational waves have died down) retains its event horizon. "Mathematically, 'naked' singularities, or those without event horizons, can exist, but physicists wouldn't know what to make of them. All known mechanisms for the formation of singularities also create an event horizon, and Penrose conjectured that there must be some physical principle — a 'cosmic censor' — that forbids singularity nakedness ..."
from the also-no-hair dept. (Score:5, Funny)
Oh jeez.
Thats a lot of equations. (Score:2, Funny)
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Isn't Kaos Greek? Then, you would be able to understand the equations. I get it, I just don't have mod points.
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Does anyone else get sad? (Score:4, Insightful)
Does anyone else get sad at the thought that there are so many weird things in the universe you may not learn the answers to in your lifetime? What if everyone posting here never finds out the reason for the cosmic censor? Sort of depressing.
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Or, if you want to go new age, just have "faith" in the singularity, life extension, cryonics and postulate that the probability is that you'll be immortal.
Re:Does anyone else get sad? (Score:5, Insightful)
Does anyone else get sad at the thought that there are so many weird things in the universe you may not learn the answers to in your lifetime?
I would submit that this is the lament of every intelligent being since the dawn of time (assuming there is a dawn of time).
Re:Does anyone else get sad? (Score:5, Funny)
Having the massive intellect to comprehend the answers to all these questions does not make one less depressed.
Marvin.
Re:Does anyone else get sad? (Score:4, Insightful)
For in much wisdom [is] much grief: and he that increaseth knowledge increaseth sorrow.
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I get sad assuming there be intelligent beings about. Oh well...
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It got harder for us not that long ago...when we realised there's apparently nothing fundamental that would stop technological progress to the point allowing indefinite life extension.
But we're not sure at all if we'll see those days.
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Nothing fundamental as far as we know, but we are not there yet (as far as I know, at leat :-)
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Indeed. My father made some passing comments about my generation being the one which would see "indefinite life extension" which (unsurprisingly perhaps) got lodged in my mind. Recently I realised it's still probably a long way off and having to readjust a rather large assumption I hadn't realised I'd made.... :(
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Re:Does anyone else get sad? (Score:5, Insightful)
Re:Does anyone else get sad? (Score:4, Insightful)
Cosmic Censor (Score:5, Funny)
Penrose conjectured that there must be some physical principle â" a 'cosmic censor' â" that forbids singularity nakedness...
God, is that you?
Re:Cosmic Censor (Score:5, Funny)
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the really funny thing about that, is that the word mass we use to refer to how much of an object there is, originates from the Christian meaning of it.
Re:Cosmic Censor (Score:5, Funny)
Re:Cosmic Censor (Score:5, Interesting)
Cosmic pun!
The name is derived from the Latin sacer, "sacred", a translation of the Greek hieron (osteon), meaning sacred or strong bone.[1] This is supposedly because the sacrum was the part of an animal offered in sacrifice. In Slavic languages and in German this bone is called the "cross bone".[2]
- http://en.wikipedia.org/wiki/Sacrum [wikipedia.org]
So keep on gyrating those sacred hips. :p
Re:Cosmic Censor (Score:4, Funny)
Re:Cosmic Censor (Score:5, Funny)
Now stop touching yourself.
Singularity nakedness on Slashdot (Score:5, Funny)
There is no singularity (Score:3, Insightful)
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There is no magical singularity where the laws of physics break down. There doesn't need to be.
Whatever helps you sleep at night, dude.
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He's right tough.
Just because we can't look inside, doesn't mean that everything breaks down inside.
People often see a black hole as something magical, and think, the Schwarzschild radius is some magical wall.
It's just the distance, at which gravitation is stronger than everything else, so we can't get useful information from the inside. Although maybe with entangled particle-pairs we could get information out!)
About the inside we know nothing. It's not the physics that break down. It's the formulas and the
Re:There is no singularity (Score:5, Interesting)
If I'm recalling correctly Hawking addressed that issue in Brief(Briefer?) History of Time. He explained that for small black holes the difference in how strongly gravity is pulling one end of you(feet) compared to the other end(head) would tear you apart before you could reach the event horizon. Large black holes (on the order of millions of stellar masses, like the ones at the center of galaxies) would be a much more gentle ride intially. In fact he said, you could pass right through the event horizon and not notice anything particularly weird happening. You wouldn't even notice. Nevertheless as you get closer to the singularity at the center you'd still get ripped apart.
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Time is only moving slowly as viewed by an outside observer. An observer would see you take an infinite amount of time to cross the event horizon. But from your point of view, time continues on as normal.
As you cross the event horizon you wouldn't notice anything unusual, you would still see the outside universe behind you and the event horizon would still appear in front of you. In fact, from your own point of view, you would never reach the event horizon, it always appears in front of you at the same dist
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No, GP is right. Your time would pass normal for you, but the time of everything outside the black hole would pass faster and faster, meaning you'd get more and more radiation and faster and faster star movement, until the sky is completely white. But I guess you'd be dead by then.
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The event horizon is the point at which it would take infinite energy and breaking time-space to escape; but if you are being sucked in, you will not notice anything strange. To something being sucked in, the event horizon is meaningless, because you already could not have escaped long before. There are no strange effects on time simply from reaching the event horizon, but as you accelerate inwards, time would appear to speed up as you move ever closer to the speed of light.
As well, light
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IDTYDRC (I don't think you do remember correctly) - your own timeframe would continue as normal, but outside observers, free from the effects of the black hole's gravity, would see you slowing down and freezing at the event horizon - so they would never catch a glimpse of you experiencing the inside of a black hole.
Re:There is no singularity (Score:5, Informative)
A black hole isn't some mystical thing unrelated to the other cosmological objects. Black holes are just stars that have consumed most of their fuel through fusion over billions of years, then collapsed. But consumed doesn't mean the mass is all 'burned up' and gone, but converted from hydrogen and helium into heavier elements that are harder to participate in further fusion reactions, resulting in decreasing internal pressure from energy being released by the star. If the conditions are right, the compacting force of gravity from all the 'star stuff' that's left exceeds the declining expansive pressure provided by the fizzling nuclear reactions inside the star, and it ultimately collapses into an incredibly small size. If the size is less than the Schwarzschild radius, it will become a black hole.
But it's still just a lump of star stuff with mass like what the star had, but in a dramatically smaller package. It doesn't suddenly go on a cosmic rampage, marauding around and sucking up everything in sight. If something external has sufficient distance and velocity that it would have flown by or orbited the former star, then it will fly by or orbit the hole, as these parameters are solely determined by the masses of the star/hole and the external thing. If something would have fallen into the star, it will fall into the hole as well. Whether it falls into a black hole or a star, it's not coming back out.
Astronomers infer the properties of black holes from what they can observe about the objects that are influenced by them, and from what they observe about the progression of stars throughout their lifetimes. Just because we can't see into black holes doesn't mean they are totally mysterious.
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But it's still just a lump of star stuff with mass like what the star had
Is there any theoretical limit to the formation of new elements? Might there exist, in large black holes, ones with atomic numbers in the thousands? Are we sure that they will continue to behave according to the laws of physics as we know them?
These are not rhetorical questions -- I'm genuinely interested.
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IANAA (I am not an astrophysicist) but IIRC before a collapsing star gets to the black hole stage it would (however briefly) go through a point where gravity was sufficient to collapse atoms - a neutron star. So I don't think there are any atoms in such a black hole. (Of course, that's theory, no one has made the observation to check!)
However, not all black holes from from stellar collapse. I have no idea what the theory
Re:There is no singularity (Score:4, Informative)
Photons have no mass but do have momentum.
The Lorentz transform causes a breakdown for E in E=mc^2/sqrt(1-v^2/c^2) where v=c. And when you have enough gravity to bend space such that it folds in on itself - light cannot escape, despite being massless but gaining momentum from the gravity well - you have a singularity.
One can't just say that equations break down, but physics do not. The equations are the language used to express the known physics.
So, there is a singularity, there needs to be, and it isn't magical - unless you mean magical in the sense of wonderful.
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That would cause some other hairy problems, spelling being the least of them.
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1- Photons have no rest mass but they have energy and momentum (or relativistic mass). They are affected by gravity as they follow geodesics in spacetime, which are defined by the local mass-energy.
They original experimental proof of general relativity was by Eddington who showed that the mass of the Sun bends light in the way predicted by GR.
2- Mass by itself is not sufficient to "trap" light. A given mass contained within a given volume is, however, i.e a given density. A sufficient density creates an eve
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Photons don't have mass, otherwise they would never be able to travel at the speed of light- the energies required would be way too much.
"Pair production" [wikipedia.org] is strange though. Fire a high energy photon (at gamma wave energies) at a heavy nucleus (say plutonium), and the photon splits into an electron and positron.
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First I'll correct your spelling by removing the spurious t from photons.
Then there is the miss-use of the term black hole, at least according to my concept. From what you wrote, the proper term s/b "event horizon". You can see anything on this side of it, but whats inside it cannot be seen since the horizon diameter is in fact the distance from this object where the escape velocity equals C.
Now here is a conjecture for you, an expansion of your idea if you will.
Assume a large mass, whose gravity is so st
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Just as I suspected... (Score:5, Funny)
Right?
Re:Just as I suspected... (Score:5, Funny)
What if you reverse the polarity?
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Re:Just as I suspected... (Score:4, Funny)
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Re:Just as I suspected... (Score:5, Funny)
Have you tried logarithms? [xkcd.com]
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Non-Condradiction (Score:5, Interesting)
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Re:Non-Condradiction (Score:5, Interesting)
I believe that some solutions have space being discrete at the Planck length, rather than continuous, and this discreteness also removes singluarities.
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Discrete; you know what this means? (Score:4, Interesting)
This means that not only are we living in a simulation [simulation-argument.com], but we're being run on a digital computer.
Re:Discrete; you know what this means? (Score:4, Insightful)
-1, Unfalsifiable
Dare I elaborate, if you wanted to make up a generic unfalsifiable claim on purpose that's probably what you would come up with.
Re:Non-Condradiction (Score:5, Funny)
I believe that some solutions have space being discrete at the Planck length, rather than continuous, and this discreteness also removes singluarities.
I spent $82,000 on tube amplifiers and vintage vinyl, and now you tell me God's system is digital? Auuuugghh...
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I believe it to be best explained by the late, great Douglas Adams:
There is a theory which states that if ever anyone discovers exactly what the Universe is for and why it is here, it will instantly disappear and be replaced by something even more bizarre and inexplicable.
There is another theory which states that this has already happened.
There is a third theory which suggests that both of the first two theories were concocted by a wily editor of The Hitch-Hiker's Guide to the Galaxy in order to increase th
Penrose is a kill-joy. (Score:5, Funny)
Which is why the DVDs "Physicists Gone Wild" were never really successful. Although the LHC did turn up as the hottest collider in Europe, so far still no naked singularities.
Re:Penrose is a kill-joy. (Score:5, Funny)
They're fixing that coolant leak. Calling them hot is just uncalled for.
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Collider? I barely know her!
Confucius say (Score:2, Funny)
Confucius say "Physicist who say there is no naked singularity should examine their equations through a peep hole."
Shhh (Score:4, Funny)
You had me at naked...
Computer simulation, eh. (Score:2, Insightful)
I can't get over this sort of story. "We programmed our INCOMPLETE understanding of the cosmos into this simulation, which tells us X, therefore X is more likely."
Anything based on a computer simulation is based on our arbitrarily incomplete knowledge. To base even the least significant conclusions upon it seems laughably irresponsible and unscientific.
But hey, I was a music major, so what do I know.
Re:Computer simulation, eh. (Score:5, Informative)
A few years ago, I might have agreed with you. After all, on a basic level you are correct, if we program what we know into a simulation, the simulation will be based on what we know!
Last semester I took a class in complex system, and it really opened my eyes about what computer simulations can do for us in providing unexpected behavior. Most of this is because we have a pretty good grasp on simple systems, and can take those simple systems and program them into a computer with rules of interaction to see how they will interact without human guidance.
Let me give you an example: Most everyone here at one point of time or another have programed "Life [wikipedia.org]" into a computer. We understand the rules, we understand the program itself, and we understand how everything is going to work, but until you actually run the program, you would never have expected the results! How could you have predicted the formations that would develop? The stable formations, the chaotic formations, the moving formations? Much less how these formations would interact when they collide?
I think in a way this is what was being simulated in the program mentioned above. We think we have a pretty good idea about the simple systems which make up a complex entity like a black hole. But how do these simple systems interact when they encroach upon another black hole? Assuming we really do understand these simple systems, and that they stay constant, I think this simulation gives us a reasonable expectation as to how black holes will react to a collision.
Re:Computer simulation, eh. (Score:5, Insightful)
Anything based on a computer simulation is based on our arbitrarily incomplete knowledge. To base even the least significant conclusions upon it seems laughably irresponsible and unscientific.
We eagerly await your analytical solution to the n-body-problem. I mean, it's really simple stuff, right?
Until you're finished, we'll have to calculate all those spacecraft trajectories with computer simulations.
Move Violent?... (Score:5, Funny)
...the most violent collision imaginable: two black holes colliding head-on at nearly light-speed.
What about 3 black holes colliding head-on at nearly light-speed?
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The author just lacks imagination.
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I think Loibisch answer was closer to the truth - even closer then my own answer.
one at a time (Score:2)
Because there aren't three black hole colliding - there are two black holes colliding and then a third one colliding into the result. Remember they are travelling at the almost speed of light so the collision won't take very long.
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You probably need to get yourself an extra few dimensions to make 3 particles collide exactly head-on.
Putting a spin on things... (Score:2)
Since the most common model for the creation of a naked singularity involves a rapidly spinning black hole, I fail to understand why there should be any expectation that colliding two black holes head-on would have that effect. This sounds like pseudo-science... "look, something that wasn't expected to create a naked singularity doesn't seem to do that in a simulation, so they can't exist!"
Gravity at the speed of light (Score:4, Interesting)
Perhaps someone could educate me here but how accurate is this because surely we've never done any study into the effects of gravity at the speed of light. Doesn't gravity act differently at this speed?
Re:Here come the goatse jokes (Score:5, Funny)
It's already asking a lot for nerdlings to not snicker at any reference to a "hole".
Adding in nakedness just goes beyond any reasonable expectation of restraint.
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Re:Here come the BLACK HOLE jokes (Score:3, Funny)
Dude, that's so lame. For jokes about black holes, look no farther than the uncyclopedia.
Black hole [uncyclopedia.org]
Event Horizon [uncyclopedia.org]
Albert Einstein [uncyclopedia.org]
Stephen Hawking [uncyclopedia.org]
And of course we can't forget YOUR MOM! [uncyclopedia.org]
No go away or I shall taunt you again.
Re:Penrose is smart (Score:4, Insightful)
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Who is Dawkins?* I never heard of that guy. Or at least I can't remember.
But Penrose... of course everybody knows him, if only from the books of Hawking. ...What do you mean, nobody reads those books??? How can they even survive that way?? ;)
Oh... the bible.... right...
* Yeah, alright. I'll look it up on Wikipedia!
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He's a bloke, who, unable to come up with a a coherent explanation for consciousness decided "it must be a quantum thing". He's also great if you want someone to tile your bathroom. Am I right?
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That's him. Unfortunately, his quantum consciousness idea doesn't give an explanation of consciousness, it just gives a means for Descartes "ghost in the machine" to interact with the physical -- in other words it just moves the problem. On the other hand, I've not heard any other coherent explanation of consciousness either. And he's made more contributions to mathematics than any other philosophers of the mind that I can think of. So tempted to do my bathrooom in Penrose tiles!
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Im not sure but what moving the problem is a significant advance, maybe one Penrose didn't intend. One problem strict philosophical materialism has in practice is it tends to reject all 'supernatural' phenomina, but it does so dishonestly. That is, most believers in it claim to simply be naturalists as a method, because it's pragmatically difficult, perhaps impossible, to apply science to something that can manipulate the very laws of nature.
As I understand it, the more common assumption is that there is nothing that can manipulate the laws of nature from outside, because if there were it would be subject to its own rules and so part of (an expanded understanding of) nature. That's a metaphysical assumption, of course, but one that allows them to retain their naturalism.
Quantum Mechanical explanations aren't technically supernatural, but they tend to certain properties that supernatural explanations also have (Multiple interpretations may have equal validity
Careful! That's why they're called "interpretations", not "theories". Multiple interpretations have equal validity (though not necessarily equal utility) wherever they occur. It
Re:Black hole collision (Score:5, Informative)
And the boom from a black hole is usually in the form of X-rays or gamma rays radiation and, in energetic terms, it's very loud.
Re:Black hole collision (Score:5, Informative)
All the mass of a black hole is compacted into an extremely small region at the centre - possibly infinitely small, but at the very least as small as physics allows matter to get. This is the singularity.
When we speak of the size of a black hole, we're actually referring to the region around that central object from which nothing can escape. As you approach the black hole, the gravitational field gets stronger and stronger, and there's a point of no return at which the escape velocity reaches c, the speed of light. Nothing nearer the hole than this can ever escape. This we call the event horizon - because no events beyond the horizon can ever be observed from outside. The more massive the hole, the further out the event horizon: look up 'Schwarzschild radius' for the equation.
The result of this is that any singularities in the universe are expected to be hidden behind event horizons, and cannot be seen. It's occasionally suggested that a naked singularity might form - for instance, a black hole might be spinning so fast as to counteract the effect of gravity and allow the singularity to be viewed from outside. This could have extremely bizarre results for the universe as a whole, so most physicists expect there to be some kind of 'cosmic censorship' principle that ensures that this does not happen. What we're looking at here is one way in which that might happen.
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Well, their time slows down because of the massive gravity. So eternity here could be only couple of seconds there :)
Re:Black hole collision (Score:5, Informative)
So pity not the photon, for even an eternity is less than a moment to it.
Re:Black hole collision (Score:5, Interesting)
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Re:Black hole collision (Score:4, Interesting)
But black holes exist within the universe. If time inside a black hole is stopped relative to the rest of the universe, then shouldn't a black hole take infinitely long to form?
As a corollary, shouldn't you be able to look behind you and watch the end of the universe?
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I'll take the second point first. And believe me I'm no expert, I mearly take an interest in Astronomy and I've read quite a lot on the subject.
If you 'look' behind you as you enter a black hole you see the light that was entering immediately behind you so you see the static universe as you normally would. But as with a lot of complicated maths and physics, human language and common experience can't really serve as a metaphor for what is going on. It's an unfortunate answer to a great many questions.
Your fi
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...and this might begin to answer your question but I still find it hard to understand!
http://cosmology.berkeley.edu/Education/BHfaq.html#q4 [berkeley.edu]
Emmett Brown (Score:4, Funny)
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There's that word again; "heavy". Why are things so heavy in the future? Is there a problem with the earth's gravitational pull?
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And if two boundrys come in contact then they can't seperate without some part of the boundary exceeding the speed of light relative to another part of the boundry, smashing them together at LHC speeds won't make that happen.
Re:Physicists... (Score:5, Funny)
Re:No Naked Black Holes?! Giggidy! (Score:4, Informative)
The equations of relativity, which were used to run the simulation, say nothing about cosmic censorship. The C.S.H. wasn't formulated until 50-odd years after general relativity because of a problem - relativity actually readily admits (physically-implausible) solutions that do have naked singularities, hence the censorship. Apparently, something always conspires to hide them.
This simulation confirmed the hypothesis' prediction: Even in the most violent circumstances physically realizable, the singularity ended up behind an event horizon.
Frankly, it's time we admitted it... the only way we're going to find a naked singularity is to go for a joyride in the direction of the Great Attractor in a sycamore-seed-shaped ship.
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We don't see event horizons directly, either... we just have indirect observations of X-ray sources (like Cygnus X-1) that are best explained, under the current theories, as black holes. Current theories imply that it might be possible to create a naked singularity, but that doesn't mean that they imply such things exist... and the only tests we can do on them are theoretical.
So it seems like Penrose is making a much stronger statement than is supported by evidence.
Current theories imply that it may be poss