Black holes: a model for superconductors?

Mar 02, 2011
This artist's concept shows a galaxy with a supermassive black hole at its core. The black hole is shooting out jets of radio waves. Image credit: NASA/JPL-Caltech

Black holes are some of the heaviest objects in the universe. Electrons are some of the lightest. Now physicists at the University of Illinois at Urbana-Champaign have shown how charged black holes can be used to model the behavior of interacting electrons in unconventional superconductors.

"The context of this problem is high-temperature superconductivity," said Phillips. "One of the great unsolved problems in physics is the origin of superconductivity (a conducting state with ) in the ceramics discovered in 1986." The results of research by Phillips and his colleagues Robert G. Leigh, Mohammad Edalati, and Ka Wai Lo were published online in Physical Review Letters on March 1 and in Physical Review D on February 25.

Unlike the old superconductors, which were all metals, the new superconductors start off their lives as insulators. In the insulating state of the copper-oxide materials, there are plenty of places for the electrons to hop but nonetheless—no current flows. Such a state of matter, known as a Mott insulator after the pioneering work of Sir Neville Mott, arises from the strong repulsions between the electrons. Although this much is agreed upon, much of the physics of Mott insulators remains unsolved, because there is no exact solution to the Mott problem that is directly applicable to the copper-oxide materials.

Enter string theory—an evolving theoretical effort that seeks to describe the known fundamental forces of nature, including gravity, and their interactions with matter in a single, mathematically complete system.

Fourteen years ago, a string theorist, Juan Maldacena, conjectured that some strongly interacting quantum mechanical systems could be modeled by classical gravity in a spacetime having constant negative curvature. The charges in the quantum system are replaced by a charged black hole in the curved spacetime, thereby wedding the geometry of spacetime with quantum mechanics.

Since the Mott problem is an example of strongly interacting particles, Phillips and colleagues asked the question: "Is it possible to devise a theory of gravity that mimics a Mott insulator?" Indeed it is, as they have shown.

The researchers built on Maldacena's mapping and devised a model for electrons moving in a curved spacetime in the presence of a charged black hole that captures two of the striking features of the normal state of high-temperature superconductors: 1) the presence of a barrier for electron motion in the Mott state, and 2) the strange regime in which the electrical resistivity scales as a linear function of temperature, as opposed to the quadratic dependence exhibited by standard metals.

The treatment advanced in the paper published in shows surprisingly that the boundary of the spacetime consisting of a charged black hole and weakly interacting electrons exhibits a barrier for moving in that region, just as in the Mott state. This work represents the first time the Mott problem has been solved (essentially exactly) in a two-dimensional system, the relevant dimension for the high-temperature superconductors.

"The next big question that we must address," said Phillips, "is how does superconductivity emerge from the gravity theory of a Mott insulator?"

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Provided by University of Illinois College of Engineering

4.3 /5 (19 votes)

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Waterdog
3.3 / 5 (3) Mar 02, 2011
The fundamental question for me is "what is charge?". I know what it does. I can describe it. It can be quantified, but what is it? It seems to me to be a elementary unit of the universe. It seems to be conserved even in nuclear reactions. This article seems to be implying that if you were to bombard a black hole with electrons that the charge would not be consumed by the black hole. What else can you say that for?
Alburton
2.8 / 5 (5) Mar 02, 2011
Science does scarcely confront the question of the fundamental what. The universe is a mistery so deep we dont know "what" is anything,do we?
What are you?
Kant would say we cannot know the object for itself,but only the object for me.
Doom1974
not rated yet Mar 02, 2011
In string theory, black holes appear to be described as elementary particles, therefore within that mathematical framework, they appear to be able to marry gravity with quantum mechanics.
natetuvkok
not rated yet Mar 02, 2011
Within an energy band, energy levels form a near continuum. First, the separation between energy levels in a solid is comparable with the energy that electrons constantly exchange with phonons (atomic vibrations). Second, it is comparable with the energy uncertainty due to the Heisenberg uncertainty principle, for reasonably long intervals of time. As a result, the separation between energy levels is of no consequence.
Caliban
not rated yet Mar 02, 2011
All well and good, except that an empirically real phenomenon is being extrapolated, or, mapped upon another that is yet to be quantified empirically. How do you go about proving that a BH is weakly negatively charged?
Skeptic_Heretic
5 / 5 (3) Mar 02, 2011
Not negatively charged, comprised of a slight negative balance of energy. Big difference, but your question stands.
Anthony_Milner
1 / 5 (3) Mar 02, 2011
Finally someones looking in the right direction. Relativity of inverse vortices and angular vectors at an event horizon in my view literally hold the key to the unknown Universe.
Shelgeyr
3.4 / 5 (11) Mar 03, 2011
...The charges in the quantum system are replaced by a charged black hole in the curved spacetime, thereby wedding the geometry of spacetime with quantum mechanics.


I conjecture that paragraph containing the above is truly, truly meaningless.

This work represents the first time the Mott problem has been solved (essentially exactly)...


This isn't science. This is mathematical navel-gazing.

First prove that there is such a creature as a "charged black hole", a strictly theoretical entity (and good luck with that), then that we know anything at all about its real-world behavior (we don't) which could then be related to superconductors (a real-world phenomena).

As it is, the solution presented here is "two handfuls of magic pixie dust" to solve one physics problem.

I'm not a troll. But sometimes these articles make it hard not to sound like a PRO-SCIENCE troll...
ZephirAWT
Mar 03, 2011
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ZephirAWT
Mar 03, 2011
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antialias
5 / 5 (4) Mar 03, 2011
This isn't science. This is mathematical navel-gazing.

The point is IF superconductors can be described by thei method then it can be used to predict other (better?) superconductors.
So the theory is testable - something that should be high on the agenda of the people involved.

As always in science: Theory first. Then comes the test.
ZephirAWT
Mar 03, 2011
This comment has been removed by a moderator.
ZephirAWT
Mar 03, 2011
This comment has been removed by a moderator.
antialias
5 / 5 (5) Mar 03, 2011
This method will certainly predict other superconductors or other superconductor-behavior than the standard method. So we can test it and move away from this 'trial and error' based mucking around (or 'art' as you call it) of searching for new superconductors.

Science requires theories, because science is about finding rules with which you can predict future behavior of as yet unrecorded phenomena. Everything else is just data acquisition.

No doubt, data acquisition is a valuable part of science - much like making theories - but only together they make up the scientific method.

Definition taken from wikipdeia, 'scientific method':
scientific method is: ...systematic observation, measurement, and experiment, and the formulation, testing, and modification of hypotheses
Nik_2213
1 / 5 (2) Mar 03, 2011
Truly weird science...
I won't even pretend to understand more than scraps of this article, it's so abstruse: Uh, IIRC, a black hole will *eventually* neutralise itself via Hawking radiation. What bugs me is that an electron has 'unity' charge, but quarks carry 'fractional' charges...
Shelgeyr
2.3 / 5 (6) Mar 03, 2011
If this leads to a testable theory of high-temp superconductors, then I assume it will only be due to a happy accident since we can't test black holes. Nonetheless, if it DOES lead to a testable theory, great! In that event I'll happily withdraw my "mathematical navel-gazing" snark.
ZephirAWT
Mar 03, 2011
This comment has been removed by a moderator.
antialias
5 / 5 (7) Mar 03, 2011
If it doesn't make predictions other than the standard method then it is equivalent to the standard method. in that case - depending on whether it can be formulated in a more conscise way than the standard method - it may be more or less useful.

But since it postulates a fundamentally different mechanism some discrepancy should occur: and there is where you set up the test.

This research doesn't say that black holes are involved. it just uses the mathematical methods involved in describing them (string theory) on another subject. Nothing wrong with that. Mathematical _methods_ are independent of the physical subjects they are applied to. the article postulates that a gravity equivalent can be formulated to an electrodynamic problem (and vice versa). The research to verify (or falsify) this costs next to nothing.
GSwift7
3.3 / 5 (4) Mar 03, 2011
Black holes are some of the heaviest objects in the universe. Electrons are some of the lightest.


Kinda way off topic and also kinda philosophical, but for some reason I can't help but criticize the above comment. First, I'm not sure I would call a black hole an object in the traditional sense. Second, an electron is actually quite dense in terms of the total mass/energy contained in an electron compared to its size. Third, using the word 'heavy' is a bit odd.

Oh, and one more thing:

This artist's concept shows a galaxy with a supermassive black hole at its core. The black hole is shooting out jets of radio waves


I think it's actually shooting out jets of white paint or chalk. :)
Pyle
5 / 5 (1) Mar 03, 2011
You're not even wrong. You're just naive. Do you know about some mechanism, how to avoid the paying the useless nonsensical research? If not, then you have no feedback about it.

How many billions of dollars would a room temperature superconductor be worth? Maybe a trillion? More?
Research is a risk/reward system. I would even agree that oversight can always be improved. Maybe even pegging more public money in investment portfolio style selection methods might be a step forward. But your negativity comes across as reaction to a past slight more than an objective argument.

I say flush it all down the LHC!!! Who knows? Maybe it will find your aether.
GSwift7
1 / 5 (3) Mar 03, 2011
How many billions of dollars would a room temperature superconductor be worth? Maybe a trillion? More?


Let's pretend you have one. It's a good one, but a year later I come up with a better one. How much is yours worth? :P

I agree with your post, I just like to play devil's advocate for the purpose of discussion sometimes.
Pyle
5 / 5 (4) Mar 03, 2011
I wasn't really thinking along marketing lines. I was thinking more along value to humanity lines.
To your point though, yeah. That is why funding for bleeding edge research is usually government sponsored. Companies don't want to take that initial risk. They much prefer to focus their energies on technologies that can be secured for profit after the government does the dirty work.

Back to the superconductors, the potential benefits in power transmission alone make this worthy pursuit. Who cares if the comparison in this research is likely to an impossible mathematical artifact resulting from a broken limit within GR/string theories?
beelize54
1.4 / 5 (9) Mar 03, 2011
How many billions of dollars would a room temperature superconductor be worth? Maybe a trillion? More?
Research is a risk/reward system.
This is actually the core of the problem. It's not risk/reward, because J.F.Prins prepared such superconductor before ten years already. We have these solid phase superconductors already and we don't need theorists for it. We understand this mechanism and we could even make artificial superconductive phase from carriers attracted to nonconductive surfaces with electrostatic field. But physicists are still developing dummy models instead of testing of these results. These results never appear at physorg-like news servers, because superconductor "re-search" is an industry and too many people would lose their safe jobs.

http://www.superc...276K.htm

http://iopscience...18/3/319
Pyle
4.8 / 5 (4) Mar 03, 2011
Give it up man! You and your conspiracies. Prins didn't demonstrate ANYTHING. Mere speculation and inconclusive experimental results. Haven't we all been down this road multiple times? It's not like nobody is trying to use diamonds to make superconductors. Give it a rest. And... Nobody but snake oil salesmen continue to sell cold fusion, despite their efforts to recreate it.

Sorry everyone else. Having a bad day.
beelize54
1 / 5 (8) Mar 04, 2011
..Prins didn't demonstrate ANYTHING. Mere speculation and inconclusive experimental results...
LOL, you can't simply tell this, because nobody bothered to analyze it and replicate it in peer-reviewed press. You're just like the opponents of Galileo, who refused to have look through his telescope to face the evidence. We all know, cold fusion is real, room temperature superconductivity is real and mainstream physicists are taking money whole years for research of irrelevant nonsense like alchemists of modern era - because they simply can. In contemporary science no one is responsible for ignorance of existing results. So you don't believe, it's possible? Lets face the reality.
frajo
5 / 5 (5) Mar 04, 2011
Lets face the reality.
Reality is that beelize54
prepared such superconductor before ten years
and ZephirAWT
the cooling speed measurement for determination of neutron star viscosity has been proposed before fifty years already
are two accounts of one person.
Some people are unable to learn.
Pyle
5 / 5 (2) Mar 04, 2011
Zephir, you really think that a company that could distribute energy with zero resistance and make BILLIONS upon BILLIONS of dollars in profit would be curbed by some egg heads at universities that want to keep their research money?

You really think that China would pass up the chance to use this technology to catapult itself past the western world?

I know I am asking a lot, but be reasonable. Some conspiracies are plausible and believed by people who are skeptical of the "official version". Some are believed only by nutjobs. Just because you keep repeating a conspiracy doesn't make you one of the former. We know you are reasonably intelligent. Your math skills and knowledge of science are well above the average person. Try to analyze your beliefs a little bit and reflect on your posting. Unless it is all just for a laugh, in which case, you are funny but it is getting tired.
Skeptic_Heretic
5 / 5 (3) Mar 05, 2011
The reason why large secret conspiracies don't exist is because people are not good at keeping their mouths shut.

If one person happened on superconductivity, they most assuredly had assistants and associates working on the project. The larger a project, the larger the secret society would have to be. The larger the society of secret conspirators, the greater the possibility of a leak. Then of course there's always the fact that if it was discovered or leaked you'd need to bring those people into the fold, resulting in an even larger conspiracy, with more people, and bigger leaks, resulting in more people picking up the research and discovering HTSC, resulting in .........

This is why people like you make me laugh, Zephir.
ab3a
5 / 5 (4) Mar 05, 2011
As always in science: Theory first. Then comes the test.


Usually the hypotheses are the result of attempting to explain experimental results and observations. If it is tested and confirmed to be reasonably accurate, we call it a theory. It is rare that an hypothesis come about strictly from a mathematical perspective. And then for that hypothesis to have no readily testable aspects to it?

That's no theory. I'm not even sure one could call it an hypothesis. Until it can be tested, it is a lot of mathematical doodling.

THAT is why there are so many physicists who express doubts.
beelize54
1.8 / 5 (5) Mar 05, 2011
@Pyle: Show me some attempt for replication of J.F.Prins experiments published in peer-reviewed article (a link). Without it your comments are pure conspiratorial speculations.
CrossMan
not rated yet Mar 24, 2011
To those you are bothered by the fact that charged black holes need not exist, let me say that this is no obstacle to what this work accomplishes. The Maldacena mapping is used to map a difficult problem onto an (presumably) equivalent problem, but one described by different mathematics, and which is hopefully easier to understand. It doesn't matter if the new math describes something real, since the math itself can be studied directly.

As an analogy, consider many masses connected to each other by springs and making them oscillate. The resulting motions are very complicated to describe because the behavior of any one mass depends on its neighbors -- the system is highly coupled. But, you can transform the problem to an equivalent uncoupled system (which need not exist in reality), which is very easy to solve because the solutions are independent of each other. Those solutions are mapped back to the original problem, and we learn something about coupled oscillation.

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