Posted on 03/09/2006 8:34:42 PM PST by snarks_when_bored
DARK energy and dark matter, two of the greatest mysteries confronting physicists, may be two sides of the same coin. A new and as yet undiscovered kind of star could explain both phenomena and, in turn, remove black holes from the lexicon of cosmology.
The audacious idea comes from George Chapline, a physicist at Lawrence Livermore National Laboratory in California, and Nobel laureate Robert Laughlin of Stanford University and their colleagues. Last week at the 22nd Pacific Coast Gravity Meeting in Santa Barbara, California, Chapline suggested that the objects that till now have been thought of as black holes could in fact be dead stars that form as a result of an obscure quantum phenomenon. These stars could explain both dark energy and dark matter.
This radical suggestion would get round some fundamental problems posed by the existence of black holes. One such problem arises from the idea that once matter crosses a black hole's event horizon - the point beyond which not even light can escape - it will be destroyed by the space-time "singularity" at the centre of the black hole. Because information about the matter is lost forever, this conflicts with the laws of quantum mechanics, which state that information can never disappear from the universe.
Another problem is that light from an object falling into a black hole is stretched so dramatically by the immense gravity there that observers outside will see time freeze: the object will appear to sit at the event horizon for ever. This freezing of time also violates quantum mechanics. "People have been vaguely uncomfortable about these problems for a while, but they figured they'd get solved someday," says Chapline. "But that hasn't happened and I'm sure when historians look back, they'll wonder why people didn't question these contradictions."
While looking for ways to avoid these physical paradoxes, Chapline and Laughlin found some answers in an unrelated phenomenon: the bizarre behaviour of superconducting crystals as they go through something called "quantum critical phase transition" (New Scientist, 28 January, p 40). During this transition, the spin of the electrons in the crystals is predicted to fluctuate wildly, but this prediction is not borne out by observation. Instead, the fluctuations appear to slow down, and even become still, as if time itself has slowed down.
"That was when we had our epiphany," Chapline says. He and Laughlin realised that if a quantum critical phase transition happened on the surface of a star, it would slow down time and the surface would behave just like a black hole's event horizon. Quantum mechanics would not be violated because in this scenario time would never freeze entirely. "We start with effects actually seen in the lab, which I think gives it more credibility than black holes," says Chapline.
With this idea in mind, they - along with Emil Mottola at the Los Alamos National Laboratory in New Mexico, Pawel Mazur of the University of South Carolina in Columbia and colleagues - analysed the collapse of massive stars in a way that did not allow any violation of quantum mechanics. Sure enough, in place of black holes their analysis predicts a phase transition that creates a thin quantum critical shell. The size of this shell is determined by the star's mass and, crucially, does not contain a space-time singularity. Instead, the shell contains a vacuum, just like the energy-containing vacuum of free space. As the star's mass collapses through the shell, it is converted to energy that contributes to the energy of the vacuum.
The team's calculations show that the vacuum energy inside the shell has a powerful anti-gravity effect, just like the dark energy that appears to be causing the expansion of the universe to accelerate. Chapline has dubbed the objects produced this way "dark energy stars".
Though this anti-gravity effect might be expected to blow the star's shell apart, calculations by Francisco Lobo of the University of Lisbon in Portugal have shown that stable dark energy stars can exist for a number of different models of vacuum energy. What's more, these stable stars would have shells that lie near the region where a black hole's event horizon would form (Classical Quantum Gravity, vol 23, p 1525).
"Dark energy stars and black holes would have identical external geometries, so it will be very difficult to tell them apart," Lobo says. "All observations used as evidence for black holes - their gravitational pull on objects and the formation of accretion discs of matter around them - could also work as evidence for dark energy stars."
That does not mean they are completely indistinguishable. While black holes supposedly swallow anything that gets past the event horizon, quantum critical shells are a two-way street, Chapline says. Matter crossing the shell decays, and the anti-gravity should spit some of the remnants back out again. Also, quark particles crossing the shell should decay by releasing positrons and gamma rays, which would pop out of the surface. This could explain the excess positrons that are seen at the centre of our galaxy, around the region that was hitherto thought to harbour a massive black hole. Conventional models cannot adequately explain these positrons, Chapline says.
He and his colleagues have also calculated the energy spectrum of the released gamma rays. "It is very similar to the spectrum observed in gamma-ray bursts," says Chapline. The team also predicts that matter falling into a dark energy star will heat up the star, causing it to emit infrared radiation. "As telescopes improve over the next decade, we'll be able to search for this light," says Chapline. "This is a theory that should be proved one way or the other in five to ten years."
Black hole expert Marek Abramowicz at Gothenburg University in Sweden agrees that the idea of dark energy stars is worth pursuing. "We really don't have proof that black holes exist," he says. "This is a very interesting alternative."
The most intriguing fallout from this idea has to do with the strength of the vacuum energy inside the dark energy star. This energy is related to the star's size, and for a star as big as our universe the calculated vacuum energy inside its shell matches the value of dark energy seen in the universe today. "It's like we are living inside a giant dark energy star," Chapline says. There is, of course, no explanation yet for how a universe-sized star could come into being.
At the other end of the size scale, small versions of these stars could explain dark matter. "The big bang would have created zillions of tiny dark energy stars out of the vacuum," says Chapline, who worked on this idea with Mazur. "Our universe is pervaded by dark energy, with tiny dark energy stars peppered across it." These small dark energy stars would behave just like dark matter particles: their gravity would tug on the matter around them, but they would otherwise be invisible.
Abramowicz says we know too little about dark energy and dark matter to judge Chapline and Laughlin's idea, but he is not dismissing it out of hand. "At the very least we can say the idea isn't impossible."
Then you mean I employing a generally light-hearted tongue-in-cheek imitation of another's style; although jocular, it is usually respectful...
Wrong again, #2! 
snarks is saying your are Pastiche... A Tucson, Arizona, restaurant that celebrate your holidays with American cuisine with world influences - fabulous appetizers, salads, sandwiches, pastas, large entrees, and desserts. Gad! Everyone knows that!
I guess they would be "suborbitals"....and I strongly suspect the binding energy would be equivalent to that which binds a booger to a finger...
Is that binding energy measured in units of flick-strength?
"By the time I get to Tucson, I'll be hungry..."
Thank you, snarks. And next on "American Idol" we have...
Old Bones McCoy singing the Gerber Brothers' latest hit...
"My baby's dead..."
Bender2, you're too much!
Interesting. The interior of a dark energy star seen from inside might look like there had been a Big Bang 14.5 billion years ago.
Mostly in the eyes, forehead, and cheekbones...
Lisa Randall
Sarah Michelle Gellar
I mean, hey, as long as we're discussing heavenly bodies...
Didn't see that mentioned in this post of yours, snarks.
On other notes, two questions:
1) Wasn't it Chandrasekar who first predicted the necessary multiples of solar mass to lead to black holes vs. other fates? With that in mind, what is the proposed mechanism for one of these alternatives to black holes? Does this theory's requirements for the original stellar mass agree with conventional theory? (Complementarity principle on the one hand, another tool to differentiate between the theories on the other.)
2) Hate to ask this, since it's over my head. (Not that accomplishing that takes much...)
But we're always talking about reconciling quantum mechanics and general relativity. Can anyone point me to a concise description of where the contradictions occur?
I am wondering about the description of the interior of a black hole--if you reach a "singularity" then wouldn't tidal forces eventually become significant even over q.m. scales --e.g. what would that do in terms of commutation of q.m. operators, etc. etc.
No flames, please, it's Friday night and I'll just pour beer on them anyway :-)
Cheers!
There's no room for controversy, there. Angular momentum is conserved, and has to be, because we observe space to be isotropic. And that has to apply to a black hole. Observe: suppose we had a huge collection of dust particles, and that the collection had some amount of angular momentum. Suppose further that it was allowed to collapse, and that its mass was so large that by the time it achieved black hole density, it was still rather rarefied.
[Geek alert: The density of a black hole is inversely proportional to the square of its mass, so very large black holes can have very low density.]
To any observer inside the cloud--and thus inside the black hole, although he doesn't know it--the cloud still has its angular momentum. To any observer outside, all they see is an event horizon, but since the whole arrangement was generally isotropic (except for some flattening of the cloud during its collapse), and certainly space itself was, the angular momentum still has to be there. The observer will find it easier to measure this if the cloud had some charge, but it's still there either way, by symmetry.
But we're always talking about reconciling quantum mechanics and general relativity. Can anyone point me to a concise description of where the contradictions occur?
Consider the electron and its electrical field. As far as we can measure--and we can measure to incredibly small scales--the electron is pointlike. This poses a problem for classical electromagnetism: when you calculate the energy of the field, it's infinite. So in classical E&M, they cut the calculation off by assigning a radius to the electron, which can be calculated from the electron's mass.
Quantum field theory has the same infinite quantity, but because of symmetry, something miraculous occurs. The quantum field is represented by both real and virtual particles (photons). It turns out that both the real and the virtual contributions cancel each other, term by term, leaving a calculable residue that agrees with experiments to ten or twelve decimal places! The fundamental quantities are truly infinite, but the calculations of measurable observables yield finite quantities. This property is known as renormalizability.
A gravitational field carries two units of angular momentum for every unit of momentum. This means that any quantum field theory of gravity will be quantized into spin-2 particles, unlike photons, gluons, or the W and Z bosons of the weak interaction, all of which are spin-1 particles. The conflict is that no spin-2 field can be renormalized in four dimensions. Any possible 4-dimensional theory of quantum gravity necessarily yields infinite quantities from its calculations. So either the universe is very different from what Einstein envisioned, or the gravitational force cannot be described by quantum mechanics.
As it turns out, there are only two spaces that permit spin-2 fields to be renormalized: one space has 26 dimensions, the other has 11. That's certainly different from what Einstein envisioned, and that's why the various string theories use one or the other of these spaces.
Calista Flockheart
Lisa Randall
Something waif-like about both of them (in appearance, that is). Some sadness to the eyes.
Branes and beauty...
Cheers!
Dark matter is what my wife buys but I never see around the house...
Snarks, I now have the introduction to the readings on renormalization you gave me... :-)
Cheers!
Physicist, the "controversy" was in some reading from (oh, say) 25 or 30 years ago--and it was casual, not professional reading for me. Thanks for helping out !
From Motl's blog, the 2 billion K generator...
Starship Enterprise.
Any questions?
Yes, ...Scotty?
Cap'n, I dinna if the thread, she canna talk much more 'o this
Cheers!
Hmmm.. black holes......crystals?...
Thanks for the ping!
Very nice post, Physicist.
No, not $10,000, just $50 for his book. His breakthrough work is based on the Rydberg Equation, fractional possibilities thereof. You've heard of fractals, yes? About the same basic idea here, plus the spectrum of hydrinos has been found in the UV part of the solar spectrum, the same way helium was first discovered. Dr Mills theory predicts those spectral lines to within .05% of actual. Throwing brick bats won't make hydrinos go away. And if you didn't know, Dr Mills' hydrino-compound patent was denied in federal court upon spurious Bohr Radius grounds(big oil/vested interests behind the curtain). If he had gotten his patent, electric batteries with 500 times the energy density of lead acid batteries(5000w-h/#)would now be on the shelf.
Actually I went online and looked at hydrinos.org. On there I found several links which purport to point to mathematical derivations of the principles. There is nothing. There are some things cribbed from other sites to add 'fluff', but other than pretty pictures, there is nothing.
He does include a few pictures which seem to describe the n=1/2 orbital. This is Barbra Streisand. There is no such thing. It is flatly impossible, due to the Planck constant, the electron mass and quantum mechanics. There is no n=1/2 orbital in the free hydrogen atom. You can derive the spectrum for the hydrogen atom in any quantum mechanics text and show it for yourself.
Now, you may say that I am arrogantly dismissing him because he has come up with a new method of doing things that is revolutionary. This is also completely impossible, since I, myself, have revolutionized my own fields of research several times in my own career.
I have found far more efficient ways of inverting the Eikonal equation than existed in the past.
I have found techniques for improving the understanding of plasma chambers (note, ions, electrons and nuclei, hint hint).
I have significantly improved the rate and accuracy at which simulated radar displays can be performed.
Each of these were confusedly understood at first by others, but I had demonstratable results that I could put on the table, along with code and experiments that everyone could examine. They are now all accepted standard practice. Each also has had a significant economic impact.
Now, as far as 'big oil interests' Dr. Mills doesn't know the first thing about protecting his intellectual property, or actually he does, since his I.P. lawyer must have told him. You do it this way:
1) Build the battery FIRST, while notarizing your lab notebooks.
2) Then patent it, while submitting notarized copies of your lab notebooks.
Now the scientific community and 'big oil' have an operating object to cope with and a paper trail that demonstrates that he did it. Mills may now collect his royalties and Nobel Prize.
EVERY scientist who has ever patented knows this. Dr. Mills has not done this, therefore he is a LIAR.
Now that you have demonstrated your ignorance in both basic science and intellectual property law, would you like to show it in any other fields?
While black holes supposedly swallow anything that gets past the event horizon, quantum critical shells are a two-way street, Chapline says. Matter crossing the shell decays, and the anti-gravity should spit some of the remnants back out again. Also, quark particles crossing the shell should decay by releasing positrons and gamma rays, which would pop out of the surface.
Now, consider that the "steady state" universe theories require only a small amount of matter (a few atoms per cubic meter) "re-appearing" in interstellar space to account for the expansion factors: It's interesting to question whether these atoms could come from such stars. Or from Hawking's black-hole quantum centers.
To me, it makes no logical sense to follow a "pure math" black hole where everything becomes a point source. That's merely a mathematical convenience, not realty.
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