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Black Holes 'Do Not Exist,' Contends Physicist
SpaceAdmiral writes "Nature reports that, according to a physicist at the Lawrence Livermore National Laboratory in California, 'It's a near certainty that black holes don't exist.' George Chapline argues that the collapse of massive stars is more likely to lead to dark energy stars. These dark energy stars behave somewhat like a black hole outside of the surface, but the negative gravity inside could cause matter to 'bounce back out again.'"
Perhaps stars really do collapse and that energy forms a new star composed entirely of "dark matter". It just seems a bit odd. Didn't LANL or BNL create a black hole for a few seconds, several times? Are they denying their findings or simply restructuring them?
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I never know if this is one of those messages that you never hear about again, or if it's one of those that you will remeber reading in 20 years, because it meant so much...
If this is totally true, i will mean a paradigm shift, a new way of thinking..but I still wouldn't want to be near a collapsing star..
Is dark energy "negative" energy? If so, if one could find a way how to get dark energy, the alcubierre drive could become a reality in the far future? I know that it need heaps of negative energy, but afaik someone corrected the calculations, resulting in much less energy consumption.
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This idea that "singularities" don't really exist has been around for a few years now. The idea is that a very small bubble forms that is unable to compress into a singularity because of the "dark energy" concept of reverse-gravity. However, the new theories that "dark energy" really doesn't exist, and that the expansion of the universe can be explained by the negative higgs field + spacetime ripples of the early inflation of the universe run contrary to this "no black hole" concept.
Someone you trust is one of us.
I tend to agree. There are several theories that look quite... um, far-fetched. But they are the best thing we have right now for describing the universe. However, experimental and theoretical physics really seem to be a mess. For instance, to explain the structure in the universe, one introduces an inflation in the early eras of the universe. Why this happened is totally unclear. It almost looks like a desperate try to introduce something just to make the results look right. One can rightly claim that the theory could be wrong. Feel free to do so. But then you have to introduce a *new* theory, and it has to pass Occam's Razor. But, considering the extremely bizarre nature of current "serious" theories, I wonder how one can laugh at stuff like cold fusion etc. It seems a little bit ignorant to me, especially since the very topic of cold fusion hasn't been either proven or disproven yet, just like string theory, quantum gravity etc. etc.
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What did they do?: http://science.slashdot.org/article.pl?sid=05/03/1 7/1541230&from=rss
>Linux is not user-friendly.
It _is_ user-friendly. It is not ignorant-friendly and idiot-friendly.
I mean , I have never felt "confortable" with the theory of black holes, it seems somewhat anthemic to true science, kind of like phlogiston
Over the past few years, observations of the motions of galaxies have shown that some 70% the Universe seems to be composed of a strange 'dark energy' that is driving the Universe's accelerating expansion
Ah, but I at least one theory exists that says dark energy isn't really needed.
Not there's anything wrong with having different theories, we'll let observational data sort it out later. Could a physicist around here explain how these proposed dark energy stars could explain the expansion of the universe if they behave exactly like black holes outside the event horizon?
Warning: Opinions known to be heavily biased.
The researcher is claiming that his theory accounts for both dark matter and dark energy, as well as some observations like x-ray bursts from the cores of active galaxies.
Conventional theory doesn't tie dark matter to dark energy at all. If the popularizations hadn't used the word dark in both cases, the two concepts would easily be completely unrelated.
Several candidates for dark matter are very conventional forms of matter, such as neutrinos or even plain old neutronium, which don't need an exotic explanation. Others involve particles we have produced in accelerators or theorize on the basis of data we have obtained ever since the 1940's.
Dark Energy, o.t.o.h., is something very different. The evidence for it is all very recent, and the theories proposed are all well outside the standard model for Cosmology.
Thinking we even need a single theory to explain both only makes sense if you can first disprove the more conventional explanations for dark matter.
Who is John Cabal?
If the event horizon is a function of gravity, shouldn't it be easy to escape a black hole using a magetic drive? Last I checked magnatism was orders of magnitude stronger than gravity. This means there are 2 event horizons, one for gravity and the other for magnetism. It should be possible to escape a black hole up to the point of the magnetic event horizon. (I assume the black hole generates a magnetic field. If not then, using mag drives should allow one to navigate freely.)
Just a thought...
Slashdot's rate-of-post filter: Preventing you from posting too many great ideas at once.
Athletic Scholarships to universities make as much sense as academic scholarships to sports teams.
Maybe this would add further weight to Hawking's proof of the black hole information paradox. If the anti gravity bounced 'stuff' back, perhaps Hawking's equations are simply predicting this? Or maybe I'm talking crap.
So the matter is repelled at the horizon when matter falls apart, thus the black hole cannot swallow the mass of the collapsing star? How does he get a horizon then firsthand? Without a collapse he cannot have this effect. When there is a horizon and he is right with his claims, this would only mean once formed a black hole would not grow. However, the existence of Sgr A* already proofs this is wrong, because there are no stars with 4 10^6 solar masses to form it in a collapse. It needs to be grown out of accreted material (which he claims is impossible). He also doesn't explain how the negative energy can collapse (and where it comes from). So he replaces one problem with another one.
Copernicus wasn't pressured for releasing info the world being round but for stating the sun was the center of the solar system. The favored model of the universe at the time was the Ptolemic system (back from the Roman time). And the Ptolemic model states the world is round. Also look at Roman coins you can see they definately though the world was round since they show a round Earth being held by a god (forget which one and might of been a goddess). The idea that the majority of people actually believed the world wasn't round was created by Mark Twain and a group of other back when they were alive for some political reason at showing how Europe was backwards thinking and America was forward thinking or something along those lines.
I guess this new article combined with an older article: http://science.slashdot.org/article.pl?sid=05/03/2 4/2242219&from=rss
Proves that physics is still very theoretical. Then again, I always felt that dark energy, and possibly dark matter will inevitably be proved to be about as real as the "Aether" theories. Like Cheech and Chong said in the 70's; If it looks like dog shit, smells like dog shit, and tastes like dog shit......... We always try to explain things by saying something unobservable is the factor causing the observations we can make. My uneducated guess is we will find that neither of these are necessary, and someone will be able to fill the holes.
Four fucking pages?!? The guy claims to comprehensively contradict some of the best known and most studied concepts in astro-physics, and his proof covers FOUR PAGES? And contains almost no equations?
Let me remind you that Einstein's paper about special relativity took only one (or was it two) pages.
Please don't apply the standards of French sosiology to the physics.
Give people more credit than that. You're telling me that 30% of people today haven't seen a picture of the planet from outer space? More like 1%. And that 90% before 1900 is certainly higher than it should be, although I won't make any blanket claims since I was not living at that time.
An object does not have to reach escape velocity to escape a planet's gravitational pull.
;)
;)
You're partly right. You can NEVER escape a planet's gravitational pull. It just keeps pulling, no matter how far you go.
Escape velocity is the inital speed needed for a ballistic object to ensure that the gravitational pull of the planet will never be able to bring it to a complete stop, relative to the planet. As you move away from the planet, the gravitational force weakens. If you can move away faster than the force can slow you down, then the gravity of the planet can never stop you. That's the escape velocity.
However, for a rocket (or other powered device) to escape a planet's gravitational pull, as the GP said, all it has to do is provide enough vertical thrust to provide a positive acceleration. That acceleration does not have to accelerate it to the escape velocity - in fact, you could adjust it to compensate for the falling gravitational pull and so maintain a constant velocity of whatever you want, and (if you have sufficient power/fuel) you'll still escape.
In theory, you're partly correct here. If you could overcome gravity to provide a 1 foot per second squared upward accelleration, then yeah, you'd get to outer space. Eventually. It'd take one hell of a lot of fuel though, because you're only barely overcoming gravity. It's not actually *possible* because no ship exists that can do that and also have enough fuel to do it.
Any acceleration larger than gravity will get you there eventually if you assume enough fuel. And as gravity drops off due to distance, eventually you'll be travelling faster than escape velocity for the given height you happen to be at. And then you're free.
That doesn't work for a black hole because all of that is based on Newtonian mechanics, which do not apply in the large gravitational fields close to the event horizon. There, you must use General Relativity, which is counter to our everyday common sense view of the world (precisely because on our scales, it's irrelevant). I don't know enough about GR to demonstrate why this is, however.
The main reason is similar to the above: You don't have enough fuel. And not just because the technology doesn't exist, but because inside the event horizon, the acceleration due to gravity is so high that even light itself isn't moving fast enough to go "up". No amount of acceleration will let you make any forward progress at all, because you cannot possibly give it enough speed to exceed the speed of light. So you can't even go up at 1 foot per second, you can only go down.
To put it another way, inside the event horizon, space is bent in such a way that moving away from the singularity is no longer an available option.
Outside the event horizon, the normal, simple, equations still apply, more or less. The gravity is high, but the concept is the same. With a higher gravity comes a higher escape velocity, that's all. Also time dilation, but that's rather irrelevent to this discussion.
- 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.
Oh brother. I didn't even get past the first page of his paper without running into physics errors. He claims that "quantum mechanics requires a universal time". This is nonsense; quantum field theory on curved spacetime -- and, in particular, on non-stationary spacetimes which do not admit any preferred "universal time coordinate" -- is a well-developed field and is quite rigorous (as far as QFT goes); it is a proof-by-example that QM without a "universal time" does work. However, you have to accept that certain procedures of ordinary QM won't remain useful; e.g., you don't tend to work with Schroedinger equations, since, as the author does correctly point out, the Schroedinger equation posits an absolute time (and a flat space). But the Schroedinger equation isn't fundamental to quantum mechanics and is not one of the postulates of QM (heck, it's not even relativistic). You can construct canonical Hamiltonian formulations of QFT without ever referring to a Schroedinger equation.
Actually, I just continued to read more of his paper, and it seems that almost his whole argument is predicated on this false claim that "synchronous time" is incompatible with quantum theory.
His "simple thought experiment" to demonstrate why it is "wrong to assume classical GR is always correct on macroscopic length scales" does no such thing: he gives an example of a condensed matter system which is a black hole analogue (has the qualitative kinematics of an event horizon). This is also well-known, but doesn't prove that condensed matter systems can mimic the full dynamics of general relativity. Indeed, nobody has succeeded in that task (don't have a good review article, but look at the references in this paper by Visser). And even if it did prove that condensed matter systems can externally act like black holes, that doesn't prove that GR is wrong on macroscopic length scales, either.
I didn't even bother to really study the dark energy bit after these preceding flaws, but beyond that, the paper is filled with crackpot warning signs: grandiose claims (simultaneous resolution of the question of black holes, singularities, the black hole information loss paradox, dark matter, and dark energy); claims that historians will one day vindicate his obvious correctness; etc.
In short: read with an extremely large grain of salt.
I'd like to hear what S. Hawking has to say about this one.
might be just the thing needed to warp space in such a way to create a worm hole. Before now, we never thought that could be possible. It opens up possibilities to such things as time travel, and space travel through the wormhole.
That is, if this theory is true.
Remember, Slashdot does not have a -1 disagree moderation, and no, troll, flamebait, and overrated are not substitutes.
Abhas Mitra is a heavy-duty crackpot. He churns out paper after paper of nonsense. The first paper I looked at was embarrassingly wrong from just about the first page: he claimed that black holes were physically impossible, since timelike geodesics leading in to a black hole became null at the horizon (basically meaning that an infalling observer's clock no longer functions). But: not only is it trivial to prove that timelike geodesics in general relativity are always timelike for any metric (Misner et al. calls this the easiest exercise in their textbook), but what Mitra actually proved was not that the geodesic goes null at the horizon, but rather that the horizon itself is a null surface (meaning that light can be trapped there). Well duh, that's part of the definition of an event horizon. In addition, Mitra got horribly confused about the coordinate singularity at the event horizon in Schwarzschild coordinates, thinking it's real and physical as opposed to an artifact of a flawed coordinate system, whereas the better Kruskal-Szekeres coordinates (which he also used in his paper!) clearly show there is no real singularity at the horizon. In fact, Mitra tried to use the K-S coordinates to prove that event horizons are physically inconsistent, when all he actually showed (without realizing it) was the fact, well known since the 1950s, that the Schwarzschild coordinates break down at the horizon.
(I can try to find the paper I'm talking about, if you want.)
In short: Mitra is an idiot with virtually no understanding of general relativity.
As for your "Hawking was forced to agree" nonsense: Hawking did no such thing. Hawking showed a calculation that Hawking believed showed that no information is lost from black holes. Mitra did a completely different, irrelevant, and WRONG calculation, which "showed" the same thing. This does not constitute an endorsement of Mitra by Hawking.
P.S. Have you ever wondered why Mitra was demoted and his colleagues avoid him? Do you think it might have something to do with his gross incompetence at GR, rather than suppression of his brilliant ideas at the hands of the evil global science conspiracy?
P.P.S. Mitra has done good work in some areas of astrophysics unrelated to GR, from what I've heard. But he's got no clue about GR, which is outside his field.
Hawking actually disproved himself regarding the event horizon "information disappearance" thing recently. He has lost a bet made some years before, 'fessed up and paid up in front of a large audience.
However, his black-hole theories hold up for the most part, still. regardless as how you look at it, no one's actually looked more at black-holes as hawking has for the moment.
It would take more than 4 pages to convince anyone that Hawking's 30 years+ research in that area to be totally wrong.
Actually, I don't buy Hawking's disproof of his own theory, . It makes a number of unjustified assumptions (such as introducing a small cosmological constant to regulate the quantum theory, and then not removing the regulator at the end of the calculation), etc. For that matter, it rests on the assumptions of the whole Euclidean quantum gravity program, which is not too popular today; string theory, and to a lesser extent, loop quantum gravity, are the current favorites.
However, your main point is correct: there are a lot of reasons to believe black holes exist, and that general relativity applies on those scales; it would take a lot of evidence to the contrary to overturn BH's -- certainly more than some qualitative handwaving about condensed matter black hole analogs plus flawed assumptions regarding the incompatibility of quantum theory with a lack of absolute simultaneity.
> There was always something a bit more romantic
> about the sling shot
I always loathed the slingshot method precisely because it had no romance or mystery.
The original method, where Spock and Scotty do a cold start implosion of the antimatter engines in order to save the ship from its decaying orbit, well, now there's a timetravel method that'll put hair on your chest.
They even got the technobabble correct: "We are now traveling faster than is possible for normal space." I.e. faster than the speed of light while in normal, not warp, space. Very mysterious and sexy indeed!
Any nerd can tell you the slingshot method is idiotic -- the energy gained is still in the same old ballpark as normal physics, and thus could not get you going faster than the speed of light. But a controlled, never before done implosion of cold antimatter, well, what more can be said?
(-1: Post disagrees with my already-settled worldview) is not a valid mod option.
In Ye Ol' Star Trek, you travel back in time.
In Voyager, you just get turned into a giant newt. Everything else made you travel through time though.
A giant newt... the evolution of man? That's not what we'd been told by Trelane, Q and the Traveler... Wesley didn't turn into no slimy giant newt... stupid Voyager.
You can't take the sky from me...
What we've actually found are spots in the sky that appear to have such a great gravitational force, from the time and space visible bent around them, and that are emitting one form of radiation while apparently swallowing almost all other forms. All we know ultimately is that the mass of the object is consistant with what a black hole would have. But, actually, that's not the question.
The question isn't "Can we put so much mass within a small enough area that light would not be able to escape?", because that's obvious. Just keep piling it on until you get to a mass and radius so large the escape velocity of the mass you've created exceeds the speed of light. The question is what happens to matter under those circumstances - when you have that much matter, collapsed to neutrons nudged against one another, so much that the neutrons are themselves under extreme force, what happens to them? We've found examples in the sky of these objects, but the fact we can't look into such an object (because light escapes, and because they're too frickin' far away) makes it difficult to answer that question.
The physicist that's started this particular debate is saying something else might happen altogether. That the object isn't a singularity, but rather an entire phase change of the matter involved. It doesn't contradict the observations, and the observations don't describe what you believe them to.
You are not alone. This is not normal. None of this is normal.
A couple of things. The reason that energy is not released when a virtual pair recombine is because that energy was already "borrowed" from the universe in order to create the pair. This is why they are called "virtual" -- they don't exist in a form that allows us to extract energy from them. The length of time a virtual pair can exist is controlled by the uncertainly principle and is thus inversely proportional to the energy of the pair:
/(2 pi)
o le-evaporation.html
Energy x Time = h
Theoretically, if you can break the laws of physics as your device does then an infinite amount of energy would become available. The limit should be set by some physical limitation of your device. If you want to know more about background fluctuations google around for "casimir effect".
The idea of your device only allowing one sort of matter to be created might be very unappealing to physicists because you are breaking all sorts of conservation laws that are dear to their hearts. A more appealing device might be some sort of a trap for anti-matter. Remember that current atomic bombs don't destroy atoms, they just convert neutrons and protons from one grouping to another. The energy released is the difference in binding energy of the groupings. You would get much more bang for you buck if you were able to achieve total annihilation using anti-matter. But alas, this idea seems worn and hackneyed. Although there might be some interesting ideas to explore in the trap itself that holds the anti-matter.
If you really want to harness the vacuum fluctuations then I suggest using some sort of sub-sub-atomic mirrors that harness the casimir effect. The mirrors exist for a VERY short period of time, but they are so flat and so perfectly reflecting that they slam together at high speed due to the casimir effect. The mirrors should probably be made up out of strings in some configuration that is not found in nature. If fact, you would probably want to use 'branes instead of strings. This idea is probably just as ridiculous as the first but the details can be swept under a larger and perhaps more appealing rug.
The rules for creating black holes is most simply expressed in terms of escape velocity. A black hole is achieved when the escape velocity is greater than the speed of light.
1/2 mv^2 = GMm/r
v^2 = 2GM/r
On earth the escape velocity is about 11 km/s. The speed of light is roughly 300,000 km/s. So something with the mass of the earth would need to be roughly (300,000/11)^2 times smaller than the earth to form a black hole, roughly 1 cm across.
For evaporation, the follow page contains the simple formulas it sounds like you are looking for:
http://www.alcyone.com/max/writing/essays/black-h
We don't see the world as it is, we see it as we are.
-- Anais Nin