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Doubting the Existence of Black Holes
The Good Reverend writes: "It seems that there's a growing movement that doubts the existence of black holes, going against most of the rest of astrophysics. They suggest the existence of gravastars, "star-size agglomerations of "wavelike" substance" (space-time fabric, if you will). Different scientists claim to have created the "wavelike substance" in a lab, called Bose-Einstein condensates." I understand gravastars taste terrific with cream cheese and red onion.
Would that be rather like neutron stars? My understanding is that current orthodox astrophysics models meutron stars as either a Bose-Einstein state, or as (in effect) a single, very big, neutron. (Or, er, are those the same things?) C'mon astrophysicists, enquiring idiots want to know! ;)
"None are more hopelessly enslaved than those who falsely believe they are free." -- Goethe
...whether a theory, unifying the gravitational force with the other three fundamental forces, would be at odds with the existence of black holes?
:)) how a quantum view of gravity would affect theories on black holes and the birth of the universe. Basically my question is: If gravitational attraction is carried by a particle (the graviton) as is conjectured by many scientists, then how can one of these escape from a black hole any more than another particle?
:)
I have often wondered (but never had the time, inclination or intelligence to go find out
I guess that either:
a) It can't, ergo black holes don't exist;
b) It can, and Einstein was wrong somewhere;
c) There is some effect similar to the X-ray "emissions" from black holes, whereby the particles appear to come from the black hole but actually never cross its event horizon.
Which just goes to show that a little knowledge is a dangerous thing.
These sigs are more interesting tha
"It's almost impossible to form a black hole this massive in a binary system"
It is apparently difficult to prove the formation of Black Holes through physics. Methinks either black holes don't exist OR this gives more weight to the creationist theories.
"What is not posible with man is possible wiht God"
Bose-Einstein Condensates are completely unrelated to General Relativity. The theory which predicts/explains Bose-Einstein condensates is Statistical Mechanics when applied to Bosons. Numerous Stat. Mech. books include this as an example, my favorite is Statistical Mechanics by Pathria.
On the other hand, black holes are a result of the Einstein equations from General Relativity and are a result of the energy stored in the gravitational field affecting the gravitational field (don't think too hard about that or blood will shoot out your nose). It is worth noting that gravity is the only one of the fundamental forces which does this. Anyway when a sufficiently high density of mass ends up in one place (a very small place) a black hole forms, which is not quite a singularity as commonly described, but something which actually has some radius. Close to the surface of the black hole there is a whole bunch of time dilation and spacial distortion so that if you watched something fall into a black hole you would never see it enter the black hole, it would just get really flat. Inside the black hole the sign of the time coordinate and the radial coordinate of the space-time tensor, as defined in special relativity, are both reversed. This has the effect of allowing someone to travel back and forth in time (provided they survived entry), but can only move towards the center of the black hole (therefore not violating causality).
Now for how black holes are formed. As stars burn out their fuel, they colapse, fuse heavier elements, colapse, fuse heavier elements... After a while, they run out of stuff to burn. When this happens they finally collapse, and the result is determined by the mass of the star. If they arn't too heavy they will end up as a collection of protons and electrons held together by gravity. If they are heavier their gravitational forces will force the electrons and the protons to merge into neutrons resulting in a neutron star (which are really interesting in their own right). Finally, if they are really really massive the effect preventing the neutrons from colapsing into a neutron star, the Pauli Exclusion Principle, is insufficient to prevent the formation of a black hole. I think the original article is saying that the bose-einstein condensate (which applies to bosons, not fermions like neutrons) would up the amount of mass required for the final colapse by introducing some sort of boson-like state between the neutron star stage and the black hole stage. For this to happen the quarks and gluons making up the neutrons would have to be rearranged into bosons and that this would only be energetically favorable at the extreme high pressures from an object more massive than a neutron star.
All that isn't to say that black holes arn't freaky, but General Relativity needs to be disproved and some alternate explaination of the giant black holes at the centers of just about every galexy needs to be found before we say they don't exist (Achim's Razor).
I would like to point out that posting an article before the team concerned has published their paper is very bad news for the team.
What often happens is that the team becomes doubted initially because they haven't published the paper, or because the article writer doesn't know what he/she is writing about. Sometimes it blows up in their face, ala Cold Fusion.
I would also like to note that the technical quality of the article is poor and shows a lack of understanding of the subject matter.
For example:
"The location of a particle constantly varies according to a statistical pattern -- one moment it's here, another moment it's there"
This shows a complete lack of understanding of the uncertainty principle! The particle has no 'position', and as such it can't be here one moment and there the next. Its position-space wavefunction is the best we can get.
There are also quite a lot of claims made in the article that really deserve a reference - hence the problem if the only reference is unpublished - in particular I would like to see an argument for why spacetime undergoes a phase transition inside the black hole. What theory predicted this? Certainly not General Relativity, which is what predicted black holes in the first place. What modifications must be made? How is quantum mechanics used in this setting?
Note that quantum gravity is still an unsolved problem, so I'd be surprised if this prediction turns out to be spot-on. But I can't tell for sure since the paper is unpublished =(
s far as we know, once you pass this point there is NO OTHER REPULSIVE FORCE available to keep the collapse in check. The star collapses all the way down to a single mathmatical point.
On the other hand, there are the (relatively) recent measurements of distant galaxies moving faster than expected, suggesting a repulsive force weaker than gravity. If it does exist and is governed by some power law like gravity or electrical forces, then at sufficiently small distances it is stronger than gravity, thus creating an extremely powerful repulsive force.
Perhaps a sufficiently massive black hole would even achieve critical mass and create a really big bang :-)
(I'd use equations and references, but that might give me the illusion of credibility)
This story first hit /. several weeks ago. I am glad to see the astrophysics community taking it onward and upward. Me no like blackie-holes. There is that ugly problem of infinities, entropy imbalances, loss of information, and so forth - none of which appear in the gravastar model...with the added bonus that a gravastar in every other way behaves exactly like a "black hole" (gravitationally).
Cosmology DOES contain ideas of phase changes occurring during the development of the universe after the big bang, so gravastars with space-time phase changes fits in there too.
It still permits sci-fi some cool material too, so the loss of classic black holes would be no biggie on that front.
Bring REASON back and eliminate "black holes". Silly, impossible buggers they are.
In Bushworld, they struggle to keep church and state separate in Iraq as they increasingly merge the two in America.
They don't seem to have improved their results since the last time this appeared on Slashdot. The main problem: "gravastars" require a rather bizarre stress-energy distribution. There is no reason to believe that a collapsing star takes on a configuration even remotely similar to this.
Its just semantics. And not even published semantics at that.
The real breakthrough will come when this kind of science is no longer publically judged by the people who make the theories. There is huge evidence pointing to the big-bang being totally wrong, i.e. the cobe background radiation measurements were 1000 times smaller than bigbang theory makes them...did steven hawking mention this in his book? did he fuck.
Having just read up on plasma cosmology, a theory that can be almost entirely proven in the laboratory, then reading up on big-bang which has only faith and ignorance to back it up, I find it hard to imagine any breakthrough will come very soon while the people that choose which papers/theories are made public refuse to choose any that disagree with their own personal agendas.
if you're interested read this book The big bang never happened
I don't think its entirely correct...it skips over the hubble expansion too quickly...but it certainly is an impressive theory, and most of it is proven.
pkm
This discusses the possibility of tiny black holes created by high-energy collisions (discussed in a previous Slashdot), which the researches hypothesize happens regularly in our upper atmosphere (bit of a stretch). It also discusses a novel theory as to why gravity is so significantly weaker than other local forces -- That unlike other forces, gravity acts through all the 'extra' dimensions hypothesized in super-string theory.
One of the more interesting things about the article is that it shows that with recent developments (the new Large Hadron Collider, etc.) scientists are beginning to reach a point where they can start to prove or disprove parts of super-string theory... Interesting stuff indeed!
It's not a cop-out to say that GR breaks down at some point. Nobody said that a theory has to hold under all cases; no known theory does that. It's a fact that GR breaks down at singularities. But that doesn't mean people throw up their hands and walk away. It just means that we now have to discover the laws that do hold -- i.e., quantum gravity.
Hawking has suggested that quantum gravity might alter the end state of the singularity, and perhaps the final fate of black hole evaporation, but he's never suggested that black holes don't form in the first place.
It's not true that more antiparticles than particles fall into the hole in the Hawking process. Equal numbers do. It's simply that the ones that fall in end up having negative energy, regardless of whether they are particles or antiparticles. The ones that escape carry away positive energy, i.e. are radiation.