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Negative Index of Refraction Created
Posted by
Hemos
on Thu Apr 05, 2001 05:05 PM
from the well-maybe-kinda-sorta dept.
from the well-maybe-kinda-sorta dept.
FortKnox writes "Scientists studying how a new composite material reacts with microwaves have found that the waves refract in a way the defies a law of physics. The physical formula states that the wave will refract a specific way, but passing through this new material, the wave bends in the exact opposite direction. Scientists believe this is the first demonstration of a negative index of refraction." I haven't been able to find a more scientific report about this - if you find a link, please post the link below.
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Re:slashdot physics (Score:2)
Re:Not *really* against the laws of physics :) (Score:4)
The right hand rule is not really a rule, it is a easy way to remember the direction of the positive cross product of two verticies. Its the same as putting your hands in front of your face to see which one forms an 'L' for 'Left' hand.
So tell me how these materials form a negative cross product [syr.edu] of radiation across the E and M flow?
And what does this have to do with refraction?
No links to anything. You should be...
..proud of yourself. Fooled the moderators again.
~^~~^~^^~~^
Re:Violation of a rule of thumb (Score:2)
Re:Answer to this phenomena (Score:2)
I wonder if POVRay will let me simulate a negative IOR? I wonder what that looks like? Time to whip out the gratuitous checkerboard floor!
Science papers (Score:2)
Bob
Re:So What? (Score:3)
For antenna research this will probably mean really a lot. Most probably we will also be able to locate sources of (microwave) radiation with great precision.
/jarek
Laws of Physics (Score:2)
Then there are derived equations, like the special theory of relativity and the various laws concerning the index of refraction. These equations have certain conditions and assumptions built into them and it is possible to come up with phenomena that seemingly defy them because you're breaking the assumptions they're founded on. A nail sticking to a magnet defies the law of gravity, but that's only because the law of gravity by itself assumes no other forces in action, for example.
So in short no laws of physics were broken by this. No doubt some aspects of quantum mechanics were used to undermine what is effectively classical physics.
Violation of a rule of thumb (Score:2)
<p>
They found a substance in which low energy wavelengths will travel faster than the speed of light in air. This is different than the speed of light in a vacuum, which is a constant and would really screw things up if discovered false.
Re:heeeeeelp! (Score:2)
(These 1930's physics books are loads of fun.)
Re:So What? (Score:3)
Thbbbt.
If they're not going to make the next Furby or Tickle-Me Elmo with what they discover, why should they keep getting research grants?
Re:Faster than light? (Score:2)
As for previous articles on this, IEEE Spectrum ran a story on this in January. If you have an IEEE account (or know someone who does) then you can see it here [ieee.org]. This is a short "news in brief" style of article, but it still does a reasonable job of explaining the effect. The thrust of the article was actually about the potential use of this effect in semiconductor lithography (used for printing ICs).
Spectrum also references the original paper on this effect, which appeared in Physical Review Letters last October. This paper was written by John Pendry from the Blackett Laboratory at Imperial College, London, UK. His work was preceded by David Smith and Sheldon Schultz at the University of California when they built some of this so-called left-handed material using a "metamaterial". In fact, the theoretical background for left-handed material has been around since 1968 when the Russian physicist Victor Veselago first looked at it.
So this material has been around for a little while now. You just have to know the right places to look. :-)
I did this 10 years ago. (Score:2)
Re:Faster than light? (Score:2)
~luge
Not *really* against the laws of physics :) (Score:4)
This isn't really against the laws of physics of course :) Basically if you've ever done any electromagnetism then you'll have heard of the right-hand rule which governs the interactions of the electric and magnetic fields and the directions of their wave velocities. But for this new class of composite materials we instead get a left-hand rule, meaning that Snell's law (which governs the change of angel caused by the change of velocity of EM radiation through materials) is essentially reversed...
The really unusual thing about these materials is that they exhibit negative electric permittivity and negative magnetic permeability, never seen before in any material. There are sure to be plenty of interesting applications to follow.
Re:Could be used for FTL (Score:2)
Re:Effects (Score:2)
Fiberglass and copper, eh? (Score:3)
Fiberglass and copper, eh? Well, how about the fiberglass REFRACTING it in the PROPER direction, and right after the copper REFLECTS it exactly the other way????
--
Re:So What? (Score:2)
Now, I personally own two (one in my CD-ROM drive, one in my audio CD player).
As DeadInSpace said, don't knock it just because it doesn't appear to be useful now. You never know what we might think to do with it in the future.
Cheers,
Tim
Re:Faster than light? (Score:2)
Are you saying you've gotten pulled over because the officer noticed red shift? That's pretty damn fast.
Effects (Score:3)
The origial article (Score:2)
Re:Faster than light? (Score:3)
The article from Science Magazine (Score:2)
--Ben
Re:heeeeeelp! (Score:2)
(Here in California we've got much smaller molecules.)
--Ben
Wait a minute... (Score:3)
I'm confused..
-jcr
Re:heeeeeelp! (Score:2)
heh (Score:2)
--
i am sofa king we todd did (Score:2)
What are the implications for satelite dishes? (Score:2)
Re:heeeeeelp! (Score:2)
bzzzzzt! Try again.
Cooking microwaves run at a frequency of 2.45 GHz, which is a wavelength of 12cm. Water molecules are significantly smaller than 12cm. ;-)
There are a number of rotational and (to a lesser extent) vibrational water transitions around 2.45 GHz which get smeared into a band in liquid water. The molecules absorb the microwaves to get into excited rotational states, and then collisionally de-excite during collisions with other molecules, thus distributing the energy into kinetic energy of the entire food.
[TMB]
Negative indexes are so old they seem new (Score:5)
The relative dielectric constant of a plasma (cold, unmagnitized, above the ion plasma frequency) is:
1 - wp^2 / w^2
where w is the frequency and wp is the plasma frequency. Below the electron plasma frequency, the dielectric constant of a plasma is negative. (Actually, part of my thesis addes terms to handle electron pressure and density gradient effects.)
Hell, Rayleigh (think 1900s) was using such treatments to calculate resonance frequencies for things like the sun (wp/sqrt(3) by the way).
What was somewhat new about the research referred to is they simultaneously created negative dielectric constant and a negative magnetic permeability.
However, the techniques they used to do so have been around since the 1950s and form the basis of all sorts of electron devices like traveling wave tubes (a staple of satellite communication).
Kevin
Defies, eh? (Score:2)
Somehow, I doubt it. The article headline says the same thing. The material doesn't defy anything, our knowledge of the laws is just lacking. It's a nitpick, but it's silly to say it defies the law.
The Good Reverend
I'm different, just like everybody else. [michris.com]
Re:Answer to this phenomena (Score:2)
What it seems to me is that they have discovered a material where the waves travel faster than the speed of light in vacuum (hence they refract the other way). That would be a quite interesting discovery if that was the case.
Re:heeeeeelp! (Score:2)
> joy of saving four bytes of page-0 memory
> on a 6502 box.
Actually, I do
And, I would probably fall under the category of "modern kid".
So there!
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heeeeeelp! (Score:3)
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Re:Fiberglass and copper, eh? (Score:3)
Re:No big deal, *and* not impossible. (Score:4)
Re:heeeeeelp! (Score:3)
(Big whoop, can't I do that already? Answer: no you can't. Ants are seriously smaller than the wavelength of your microwave and hence are pretty much unaffected by it- ant heaps can actually live in a working microwave!)
It allows perfect lenses... (Score:3)
Check out the following link to a PDF file:
Physical Review Letters [aps.org]
Warning: probably don't bother if you haven't studied Maxwells equations... definitely don't bother if you haven't heard of Maxwell's equations!
Re:Importance? (Score:3)
>How will this help me pick up chicks?
It won't. They will have better binoculars and be able to see you coming from miles away. It should help them find me though
Re:heeeeeelp! (Score:3)
Microwave ovens work [howstuffworks.com] by exciting molecular bonds at their resonant requencies. Notably, they pump energy into the O-H bonds in water molecules. Thus, anything containing water will be heated in a microwave oven. Ants contain water, of course...so the inside of a functioning microwave would not be a healthy place for them.
However, it should be noted that the distribution of microwave energy density inside an oven is not uniform. Designers try to focus energy in the lower-central volume, where food is most likely to be placed. What's more, the presence of food will absorb energy which might otherwise reach other parts of the oven. Therefore, ants might be able to live around the edges of the oven chamber without getting boiled internally. But this has nothing to do with their size.
--
Links, etc (Score:5)
Check out the Vinny the Vampire [eplugz.com] comic strip
No such thing as the "Laws of Physics" (Score:3)
Physics - indeed science in general - is basically a collection of so-far not disproven hypotheses - which are based on observation, experimentation and logical (mathematical) deduction.
There are no immutable 'laws' - there are only hypothesis for which no exception has been found.
It's actually really important that scientists don't think in terms of 'laws' - because most major leaps forward occur due to someone 'breaking' then re-inventing one of these laws. Or put it another way - we come across these observations which don't fit the hypothesis so we have to ask 2 questions
1) are the observations correct?
2) is the hypothesis correct?
If we think in terms of unbreakable laws we'll throw out Question 2 at the beginning.
Fortunately most scientists don't talk in terms of laws - it's a popular science term.
Re:An anti-rainbow? (Score:3)
It would interesting, except to be an "experiment", you'd have to get an art class to follow the Scientific Method, including formulating a hypothesis, falsifiability, etc.
Ummm. Yeah. Cough.
Importance? (Score:3)
Faster than light? (Score:3)
Re:Faster than light? (Score:3)
I wonder if one could make automotive paint out of this material? I could think of at least one good reason...
- J-Man
I know the feeling (Score:5)
Well wouldn't you know it? Bent Tree Drive has been under construction for a month. The sharp left curve is now a sharp right curve, followed by two sharp left curves.
There's an old saying: "Two wrongs don't make a right, but three rights make a left." It had nothing to do with this.
Anyway, it's a good thing I was behind the wheel paying attention. Had I been expecting the sharp left curve, I would have driven the Cruiser into a lake. Fortunately, I made the right followed by two lefts and we all got to the mall safely.
In my humble opinion, something similar has happened to these scientists. Perhaps the prism was under construction. Maybe they didn't see the tiny detour signs or maybe some kids snuck off with them in the middle of the night. You know in the Road Runner cartoons when Wile E. Coyote turns the sign around? I'll bet that's what happened here.
In fact, I understand the scientists also painted a tunnel on the side of a mountain and the microwaves went right into it. See? That's exactly what I'm talking about. If they're really smart, they'll watch out for the oncoming train. It would be a shame if the train hit them and squashed them flat against the front before they could collect their Nobel prize.
Re:Faster than light? (Score:3)
v=c/n
Where v is the speed of light in the medium and n is the index of refraction for that medium. This equation suggests that a material with an index of refraction of -1 would travel at -c. Clearly this can't be the case because the light would do a full reverse and leave the medium. So this equation must not work for materials with negative indices of refraction. It may be that the proper equation is something like v=c/abs(n) or something more complicated that simplifies to v=c/n for positive n. Anyway, they didn't conclude that the material had a negative index of refraction (for microwaves anyway) because of that equation. They used this equation:
n1*sin(theta1)=n2*sin(theta2)
Where n1 and n2 are the indices of the first and second media respectively, theta1 is the angle of incidence, and theta2 is the angle of refraction.
If n1 is positive and n2 is negative then solving for theta2 will give a negative value. So the angle of refraction bends in the opposite direction of the angle of incidence.
Er... Well, y'know. You can't make an omelette without um... destroying a forest. Or something.
Re:So What? (Score:3)
No.
If every discovery with no apparant use was treated the way you react, portable computers running at 1,000,000,000 Hz weighing less than 3kg would not exist today, just to name something. What if no-one ever tried to research and understand radio-activity (which would not seem very useful at the time), would we have the ability to take X-rays today? Or to try and cure cancer with it?
Scientific discoveries will almost always be of significant use, and should be treated as such. Even when there doesn't seem to be an application yet.
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