Has the Mythical Unicorn of Materials Science Finally Been Found? 238
gbrumfiel writes "For years, physicists have been on the hunt for a material so weird, it might as well be what unicorn horns are made of. Topological insulators are special types of material that conduct electricity, but only on their outermost surface. If they exist, and that's a real IF, then they would play host to all sorts of bizarre phenomenon: virtual particles that are their own anti-particles, strange quantum effects, dogs and cats living together, that sort of thing. Now three independent teams think they've finally found the stuff that the dreams of theoretical physicists are made of: samarium hexaboride."
slashdot disappoints.. (Score:3, Interesting)
this sounds like an interesting article.. so why does the summary read like an april fools joke. is this the way /. encourages intelligent discussion?
Topological insulator a misnomer? (Score:5, Interesting)
I can't help feeling that "topological conductor" would be a better name for a material that behaves as an insulator in its interior but whose surface can conduct.
Re:The Invisible Unicorn Argument (off topic) (Score:5, Interesting)
According to M-theory, ours is not the only universe. Instead, M-theory predicts that a great many universes were created out of nothing. Their creation does not require the intervention of some supernatural being or god. Rather, these multiple universes arise naturally from physical law. -- Stephen Hawking
Then the question becomes, is it possible that physical law was "written" by some super-entity with some idea of "sentience" (colloquially, a "god")? Or, perhaps, that what we know as physical law is merely a subset of some other set of laws written by some higher being? Of course, this would lead us back to the "is the universe a simulation?" question.
Consider, for instance, the SimCity series. For all intents and purposes, the game is a high-level simulation of a city. The "laws" of how the city functions (how traffic works, when and why people move in, etc), as well as some limited laws of physics (how fire spreads, how air pollution dissipates over time, etc) were all written into that simulation as a representation of a loose subset of similar laws in the world of the game designer. The "people" in the city, though abstracted, must obey the simulated laws of physics and city functions, as well as their respective places in the simulation.
Perhaps that is a considerably nonacademic example, but in that case, would the software engineer who wrote these simplified concepts of our reality as rules of SimCity be considered "god" to the simulated population? And, what would stop this universe from being a similar simulation? Could our laws of physics be an oversimplification of something far beyond our comprehension, but still conforming to the "host" universe's "physics"? Maybe even self-awareness as we know it is the ultimate form of being only in our own universe. It could simply be an abstraction of a much higher level of meta-being created by a meta-software-engineer, for a lack of a better term. If so, could that entity be considered "god"?
Re:The Invisible Unicorn Argument. (Score:2, Interesting)
For starters: Kudos for keeping it civil; that seems to be a rarity in any discussion of this sort.
Okay, then to your point: the big bang wasn't the start of reality, reality simply always was, and there happened to be a big bang.
Fair enough, but we still have a ball of stuff from whence everything came, and the cosmic accountants demand an explanation.
At the end of the day (as Baloroth noted above) we're dealing with a scenario for which neither of us can furnish what would be considered "definitive proof". But I would assert that I could show how a God COULD exist as a creator, while you could not show how the universe could either be eternal or self creating. Heres why...
If you say that the laws of the universe preceed the big bang (ie, that they are inherent in reality), you immediately run into the problem of that ball of stuff just appearing (which violates a number of laws).
If you say that those laws came in with the Big Bang, you must acknowledge that the laws may in fact be dynamic, and all science which relies on the assumption that they are static (ie, viewing distant stars with the assumption that speed of light=c) gets thrown into question; and you still havent accounted for the ball of stuff.
If you say that the ball of stuff is eternal along with reality, then you run into the question of how a stable ball of stuff could have exploded, and further how, if an eternity has already passed (by definition), we have not already spun down into an entropic cloud of chaos.
The only explanations I have ever heard are that of the multiverse from whence we came (which sounds a bit like what youre saying, and only regresses the problem one level up), and that of multiple "dimensions" (every possibility having happened in at least one of the dimensions; new ones formed as new possibilities are resolved-- which avoids a lot of the problems but is speculative at best).
I would be interested to hear how you can resolve those issues.
Re:The Invisible Unicorn Argument. (Score:5, Interesting)
Your tone and post has made me go back and read fully your original, which I apologise for not doing before. I was expecting the usual Christian nonsense, and so I didn't even read it because certain attitudes really wind me up these days. I used to be a Christian myself due to my upbringing, and I believed it all fervently for a couple of decades, but now I don't.
I see you don't subscribe to a human-like god, and I consider that reasonable. I agree that it's just as absurd to state that a god definitely doesn't exist as it does to state that one does. If there is no evidence either way, then to make an irrefutable assumption about it is dumb, on both sides. As you pointed out though, there are certain things that we can rule out, like a visible god, or one making Christians better off than other people, etc.
If you say that those laws came in with the Big Bang, you must acknowledge that the laws may in fact be dynamic, and all science which relies on the assumption that they are static (ie, viewing distant stars with the assumption that speed of light=c) gets thrown into question; and you still havent accounted for the ball of stuff.
I admit I haven't looked a whole lot into the supposed conditions for the big bang, not for a few years at least. I have read about what you're saying about the universal constants and so forth. I have no problem with the concept of the Universe collapsing and re-banging, the rules changing each time, countless other universes/dimensions/whatever. I wasn't saying that the ball of stuff is necessary stable as in it stays inert, I'm just saying that I find it more likely that stuff with no particular order eventually comes to order itself. I believe in the idea of a "god" coming to exist via that type of mechanism, but I find specifically the Abramic notions of a god with human traits that has always existed and is unchanging (that's what the bible claims) rather absurd.
We definitely can't account for the stuff. All we can say is that it's here. We can make up stories about gods and creators too, but it's patently obvious that at least 99.99999% of the stories we make up have no bearing on what really happened. Probably more like 100%. Even when it comes to science we do basically have to guess what happened beyond what we can measure, but to simply say that we can't exist without a god is making a massive recursive assumption - you then have to explain how that god can exist without another god. It's completely circular. So is saying "stuff always existed" in a way, but it's not quite as bizarre as claiming that life must have a creator rather than it being possibly for life/order to emerge from disorder.
It is all kind of absurd if you think about it. We are the Universe arguing about its own existence.. and eventually it will all be gone/meaningless/reset.
Re:are there any (Score:5, Interesting)
practical interesting applications for such a material ?
Spintronics will probably be a key practical application area. The basic idea as I understand it is that a material that exhibits strong topological insulator properties will allow for spin transport. One of the properties of topological insulators is that even in the presence of minor impurities, spin currents can be propogated quite a distance. This is apparently due to the 2d nature of the electron wavefunction on the conducting surface, the spin and the linear momentum are tightly corrolated. AFAIK, currently spintronics devices use ferromagnetic materials to create spin-coherent electric current, but apparently currents created this way have limited coherence lifetimes and thus propagation distance which limit the practical deployment.
Another reason that this is so exciting, is that it was previously assumed that graphene conductors would be needed for spin coherent transport (graphene also have a similar 2d electron wavefunction restriction to a conducting surface), but it may turn out that manufacture of these topological insulators can be done similar to today's planar circuit fabrication techniques (which to date haven't been very applicable to creating circuits of graphene wires).
There is also some possiblity that topological insulators this could be used in some quantum computing applications, but I haven't read any easy to digest papers on that yet.