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A Step Toward an Invisibility Cloak
Technology Review has a writeup on the latest advance in the lab towards an invisibility cloak made of metamaterials, described this week in Science. We've been following this technology since the beginning. The breakthrough is software that lets researchers design materials that are both low-loss and wideband. "The cloak that the researchers built works with wavelengths of light ranging from about 1 to 18 gigahertz — a swath as broad as the visible spectrum. No one has yet made a cloaking device that works in the visible spectrum, and those metamaterials that have been fabricated tend to work only with narrow bands of light. But a cloak that made an object invisible to light of only one color would not be of much use. Similarly, a cloaking device can't afford to be lossy: if it lets just a little bit of light reflect off the object it's supposed to cloak, it's no longer effective. The cloak that Smith built is very low loss, successfully rerouting almost all the light that hits it."
Similarly, a cloaking device can't afford to be lossy: if it lets just a little bit of light reflect off the object it's supposed to cloak, it's no longer effective.
Why would that be no longer effective? If the cloak reroutes 90% of the light, then you're left with 10% opacity, right? Sure, something that translucent would be very difficult to see, especially from a distance.
Direct link please!
http://www.technologyreview.com/computing/21971/?a=f
Garbage javascript broke for me and the page didn't get past a white page.
If visible light is being routed around the cloak, it could cause some serious navigation issues for the cloaked object. Maybe some objects (ships/aircraft) will only need a cloak that routes radar, leaving pilots to navigate by sight and dead reckoning (GPS uses radio frequencies, right?)
How is 1 to 18 gigahertz a swath as wide as the visual spectrum? It's much wider. This is around 4 octaves (ie, doublings of frequency). The visual spectrum is from 400 to 700 nanometers - not even a full octave.
"works with wavelengths of light ranging from about 1 to 18 gigahertz"
frequency is in hertz.
wavelength is a length, so it will be in meters or feet or inches or volkswagen bugs.
that is all. </pedantic>
"The value of a man resides in what he gives,
and not in what he is capable of receiving."
--Albert Einstein
Pics or it didn't happen.
Saying "The cloak that the researchers built works with wavelengths of light ranging from about 1 to 18 gigahertz--a swath as broad as the visible spectrum." is quite exaggerated. a range from 1 to 18 gigahertz is not as broad as a range from 400 to 750 terahertz. That is 350000 Ghz difference compared to 17 ghz difference (or many thousand cm-1 comapred to less than a few cm-1). I wonder how they say it is as broad. Article stinks, unless I missed something or made a terrible error in thinking.
C. Sagan : A demon haunted world:
http://www.amazon.com/gp/product/0345409469/
visit randi.org
The cloak that the researchers built works with wavelengths of light ranging from about 1 to 18 gigahertz--a swath as broad as the visible spectrum.
That doesn't sound right... first, the Hertz is a measure of frequency, not wavelength. And the range quoted - 1GHz to 18GHz - seems much wider than frequency range of the visible spectrum, anyway.
.. which seems to imply that the invisibility cloak won't work in the visible spectrum, anyway. Can someone who knows what they're talking about shed some light on the issue?
The English word fart is one of the oldest words in the English vocabulary.
Metamaterials are interesting enough _whithout_ that stupid invisibility shit everytime.
I mean, lenses without diffration limit are also interesting. And opposed to the inisibility stuff, they might really work.
HI O WISE PRINCE. WHT TOOK U SO DAM LONG?
Now I can see what happens inside the Girls' dorm!
Giggity-giggity-goo.
"I disapprove of what you say, but I will defend to the death your right to say it." - historian Evelyn Beatrice Hall
1-18 ghz is way way broader than a very thin swat of visible light. Just looking at the spectra should show it. Mod me actually uninformative or overrater.
C. Sagan : A demon haunted world:
http://www.amazon.com/gp/product/0345409469/
visit randi.org
Is it just me, or would this stuff work VERY well as a RADAR cloaking device?
1-18 GHz is solidly in the microwave (millimeter-wave RADAR anyone?) range...
- The race is not [always] to the swift, nor the battle to the strong. -
"Now [that] this is becoming a more feasible technology, we will start to see a lot more of it."
Heh, i thought the goal was to see a lot less of it :)
Patents Drive Free Software as Hurricanes Drive Construction Industry
So, where's the picture showing how visually effective this new cloaking technique is? I've seen the one of a guy wearing a jacket on the sidewalk and we can sorta see what's behind him but that's an old picture.
I don't believe it (much as I'd like to). Show it to me. Hell, even if they made a cloak that only obstructed "one color" (whatever that means) with 10% loss, that'd still be a huge leap.
If you can read this... 01110101 01110010 00100000 01100001 00100000 01100111 01100101 01100101 01101011
I look forward to the photo of the prototype.
Actually, all claims require adequate support for provisional acceptance. Differing standards for differing claims derives from the concept of canon which has more of a place in religion than science.
I agree it would have been nice if they'd included a demonstration vid.
Loose lips lose spit.
If it really works the way they say it does, then they can't really show it to you since you wouldn't be able to see it.
"one color" (whatever that means)
A basic understanding of the spectrum (and absolutely no RTFA on my behalf) would suggest that they mean one colour of the spectrum. So if they can cloak, say, the red spectrum, you'd show up looking a different colour than your normal sort.
Imagine looking at some purple paper and then removing the red visibility/light from it. Is it still purple to your eyes?
Me failed English...
FreeBSD over Linux. If my comments seem odd, this may explain...
"But a cloak that made an object invisible to light of only one color would not be of much use." If the color corresponded closely with the wavelength of laser weapons resistant/protective eye-wear could be developed of such materials. If one has need of a band-omit cover, say in the controlled protection of frequency-specific photosensitive material. Those are just off the top of my head, and I ain't an engineer.
Pics or it didn't happen.
Why would that be no longer effective? If the cloak reroutes 90% of the light, then you're left with 10% opacity, right? Sure, something that translucent would be very difficult to see, especially from a distance.
The Predator still got his ass shot up good with that hand-held vulcan gun, because the soldier saw the 10% of light that he couldn't cloak.
That's what you get for pissing off Jesse "the future Governor of Minnesota" Ventura.
Cloaking device or not.
You can't take the sky from me...
...and I ain't an engineer.
I bet you've a schoolteacher.
It is dangerous to be right when the government is wrong.
...to light of only one color would not be of much use."
It would be exceptionally useful if that colour was infra-red.
I don't see why they're overdoing this so much. I've been able to become invisible for a long time--all I have to do is cover my eyes!
Try it today!
"But a cloak that made an object invisible to light of only one color would not be of much use." If the color corresponded closely with the wavelength of laser weapons resistant/protective eye-wear could be developed of such materials.
We have simpler and cheaper absorptive filters for that already. But, making it invisible to the IR lasers used for laser rangefinders could come in handy, although it wouldn't take long to train tank crews to lase something next to the tank rather than the tank itself.
Maybe you could make it wideband enough to defeat IR heat sensitive cameras. That would be interesting. Would it look like an absolute zero patch rather than a hot engine? Probably wouldn't take long to reprogram the missiles to home in on the tank sized absolute zero patch rather than the tank sized hot engine patch. Leading to the "hot" new countermeasure technology of smashing open a couple liquid He dewars a couple hundred feet away as decoys. If you block all radiative heat emission, it's gotta go somewhere, maybe into a giant heat plume? Conducting it into the ground isn't a good idea, you'll get a tron-like heat trail to home in on. Maybe reprogram the missile to home in on the megawatt sized small hot air plume...
"Science flies us to the moon. Religion flies us into buildings." - Victor Stenger
Well it appears it doesn't work in the range of visible light at all:
http://www.ee.byu.edu/photonics/fwnomograph.phtml
Might work with microwaves though
Hey don't blame me, IANAB
Yea but you can only shoot that thing hand held like that if you're a beefy guy in his prime and the gun is firing reduced power pyrotechnic blanks and you limit the belt to 100 rounds.
I'd go on a Vegan diet but the delivery time from Vega is too long. --brownkitty
I fail to see what is so funny about that.
Mit der Dummheit kämpfen Götter selbst vergebens
Until I see pics of this invisible cloak, I'm not interested!
...to a blind person.
What? Blind people need their porn too.
Mit der Dummheit kämpfen Götter selbst vergebens
(disclaimer: i work in electromagnetics and have a bone to pick with metamaterials)
in general those who research metamaterials are regarded as roughly at the same level as Roswell conspiracy theorists. the math to come up with the idea is simple (don't bother with Maxwell, just use Snell's Law) but any substance that has the required negative permittivity or permeability to have zero reflection at one band is decidedly NOT negative in another. that, boys and girls, is the physics of the matter. (pun)
in practice boards of metamaterial are built by growing/printing funny shapes that create effectively negative physical quantities. most (if not all) metamaterial designs are arrived at through genetic algorithms and involve very little understanding of why they work. the process is 1. "hey computer, find me some negative effective epsilon over this frequency range" 2. walk away 3. publish whatever the computer said 4. (optional) try to build it and realize you have no idea what is going on.
additionally, often left out of these wonderous 'science' articles is the effect of polarization on transmittance. the may claim 18:1 BW in this article, but this is most likely only for linearly polarized, normal incidence waves.
for the DoD's sake, let's hope that Random Future Enemy has only a single band radar station looking directly at the incoming attacker.
ugh.
Isn't the fact that it only works for the visible spectrum a bit of a flaw? I mean, if that happens then what's to stop someone from detecting the heat released from such a device? What if they decide to use a radar of some sort? And if they've got a radar, then they know where you are before you're in a position where a "cloaking device" is effective. It just doesn't seem practical.
And sure, I suppose you could engineer something that negates all of this, but if that's what it takes to be truly effective, why not work on a design that takes all of this into account from the start?
Bah, "ain't" is a perfectly valid contraction for "am not", and has been since at least 1706. (See http://www.etymonline.com/index.php?search=ain't&searchmode=none) Proscriptionists object to it largely because it's often used for "is not", or "are not", which was seen as somehow "perverting" the English language.
In fact, though, "ain't" has been used that way since at least the 19th century.
About the worst that you can say of "ain't" is that it's inappropriate for a formal register, but so are most contractions.
Cheers,
Your Friendly Neighborhood Pedant
We may not imagine how our lives could be more frustrating and complex—but Congress can. – Cullen Hightower
We have simpler and cheaper absorptive filters for that already.
Absorptive filters for laser weapons? Really?
In any case, consider what happens if you have a big, relatively invisible glass tank-sized blob sitting on a sand dune. Glass, as we all know, is relatively transparent. Under ideal conditions, what would we see where the tank is? Sand.
The same reasoning works for the IR case. We would not see "absolute zero". We would see whatever was behind the shrouded object, as if the object was not there. That is what it means to be invisible.
But a cloak that made an object invisible to light of only one color would not be of much use.
Tell that to the Green Lantern, you insensitive clod!
Rob
7000 -> f = lambda/c -> 4.28275E+14
5000 -> f = lambda/c -> 5.99585E+14
Difference -> 1.713E+14 Hz -> 1.713E5 GHZ
About 171,000 GHZ not 17
That's what you get for pissing off Jesse "the future Governor of Minnesota" Ventura.
Cloaking device or not.
has he got time to bleed now ?
"...We've been following this technology since the beginning..."
This might be the reason why I can never find the administrator of our servers when I need. He might have been reading too much slashdot...
It's funny how slashdotters complain about invented words such as ain't which have been used before we were all born, however have no problem with invented words such as "blog".
And how would they have done that? Even TFS says that it doesn't work on visible light.
http://www.dilbert.com/strips/comic/1999-02-02
"blog" is a noun for something that didn't (arguebly) exist before
The linked page does not support this assertion. The text is pretty clear is stating that it *was* proper use *until* a certain point, and that it is currently "banned from current English". So it ain't valid today.
"1706, originally a contraction of am not, and in proper use with that sense until it began to be used as a generic contraction for are not, is not, etc., in early 19c. Cockney dialect of London, popularized by representations of this in Dickens, etc., which led to the word being banished from correct English."
all claims require adequate support for provisional acceptance
I think those that tested the hell out of relativity in the early 20th century would disagree with you. When something is so out of the ordinary or flies so much in the face of conventional wisdom, it will be tested more than something which merely "builds" on an existing concept.
You may be right, but in your purist logical thinking you are denying a fundamental attribute of humans.
If you can read this... 01110101 01110010 00100000 01100001 00100000 01100111 01100101 01100101 01101011
No matter how strong/hi-tech/sci-fi your invis-suit/armor/wall is, the stronger the radar signal and the closer you are, you will be found. No technology exists can replicate multi-partical refraction at the same or degraded length from all angles, at all times.
You may look invis, great, but when I use something other then rader, say, multi-phased laser sweeps on 'said' cloaker, you will be seen, I may die, but your cover is blown. Idea is great, tech will be 200+ years away, best to spend money on things that can help humans in 10 years.
is my dagger +5, my bracers of defense +5 and I am all set. Excellent it is all coming together nicely.
...I mean, lenses without *diffration* limit are also interesting. And opposed to the *inisibility* stuff, they might really work...
The device DOES work: At least one 'c' and a 'v' are succesfully cloaked! Of course you DID type them...
What person will donate an airborne act of love?
If its in range, just do a sonar type at high freq, and you are bound to map something.
Liberty freedom are no1, not dicks in suits.
Submitter needs to re-check his assumptions.
Why should an "invisbility cloak" only be useful if it works 100%? Camouflage is being used in pretty much every war, and it's far from perfect. A cloak that "leaks" could still be great in low-light or reduced visibility settings. It doesn't have to be "perfect" to be useful. The stealth fighters aren't really radar-invisible, either. Just very difficult to detect, and for most settings that's good enough.
Assorted stuff I do sometimes: Lemuria.org
I don't understand the focus on clothes here. Obviously, vehicles would be the first targets. And, vehicles don't care about weight, that much.
...the only reason QWERTY is popular is because when Typewriters first were introduced the word TYPEWRITER was crammed on the top line so salesmen could type it.
Are we no better than Salesmen?? Holy CRAP!
Oh wait, Shit! Nevermind..
Yyeah, I'd be more inclined to see this as more than an investor-grab opportunity if they even showed a single picture of SOMETHING. And that "picture" of the nano-structure close-up doesn't count.
I mean, couldn't they have at least wrapped a tiny piece of this material around a pencil or something to show that you can barely see the wrapped portion?
Like C'mon... seriously.
Scientist: Amazing news people! We've developed this material to be a THOUSAND times better than in the past! It's absolutely phenominal!
Person: Can we see a demonstration? A picture? Anything?
Scientist: Nnnnno.
Planet Zebeth - Metroid with a twist
Your Friendly Neighborhood Pedant
Ah, I see oxymorons are still okay.
Sure I'm paranoid, but am I paranoid enough?
That's what you get for pissing off Jesse "the future Governor of Minnesota" Ventura. Cloaking device or not.
Actually, predator wasn't injured until after he killed Ventura. That one bald dude then picked up his gun and shot randomly into the forest and injured the predator.
I always wear my tinfoil hat to prevent the NBA from reading my mind from their Aramchek sats.
Refracting the light isn't real invisibility; rendering what is behind the item on the front of the item from any possible aspect is.
It certainly has great value to the industrial scale homicidal sociopaths. Whoever is working on this needs an education in ethics. The secret may require their death or permanent 'house arrest'.
So called intellectuals have to stop giving actual weapons to small children who like to play at war and cops & robbers.