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A Step Toward an Invisibility Cloak

kdawson posted more than 5 years ago | from the can-you-see-me-now dept.

Science 197

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."

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Visibility (-1, Offtopic)

Anonymous Coward | more than 5 years ago | (#26509059)

Let's be glad there is still some visibility in this world -

http://www.pbs.org/moyers/journal/blog/2009/01/exchange_between_bill_moyers_a.html

Re:Visibility (1)

Reikk (534266) | more than 5 years ago | (#26510621)

Will this work if it gets wet? I'd like to use it in the girls locker room..

Pity it's not usable yet (-1, Troll)

Anonymous Coward | more than 5 years ago | (#26509085)

We could use in KDawson

Why not let a bit through? (5, Insightful)

artor3 (1344997) | more than 5 years ago | (#26509095)

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.

Re:Why not let a bit through? (-1, Flamebait)

Anonymous Coward | more than 5 years ago | (#26509127)

Why not just be a naked nigger at nighttime? You'd have 100% invisibility until you smile.

Re:Why not let a bit through? (-1, Flamebait)

Anonymous Coward | more than 5 years ago | (#26510055)

knock out those teeth and you'll be 100% invisible.

Re:Why not let a bit through? (5, Funny)

dotancohen (1015143) | more than 5 years ago | (#26509293)

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.

Re:Why not let a bit through? (4, Funny)

spiffmastercow (1001386) | more than 5 years ago | (#26509439)

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.

Yes, but if you look at it from a D&D point of view, you get a 90% miss chance, which is a game-breaking advantage.

Re:Why not let a bit through? (5, Funny)

bloodninja (1291306) | more than 5 years ago | (#26509621)

Yes, but if you look at it from a D&D point of view, you get a 90% miss chance, which is a game-breaking advantage.

I put on my robe and wizard hat.

Re:Why not let a bit through? (0)

Anonymous Coward | more than 5 years ago | (#26509669)

I cast Lvl 3 eroticism!

Re:Why not let a bit through? (1, Funny)

Anonymous Coward | more than 5 years ago | (#26510251)

I've always wondered if "robe and wizard hat" is code for "short dress and high heels". The things geeks will call their fetishes in order to stave off rejection from women.

Re:Why not let a bit through? (4, Funny)

Anonymous Coward | more than 5 years ago | (#26510613)

I put on my cloak and tinfoil hat.

There, fixed that for you. ;)

Re:Why not let a bit through? (3, Informative)

Anonymous Coward | more than 4 years ago | (#26510845)

Except that full concealment or invisibility only grants you 50% miss chance and you can't gain more than that.

Learn the rules!

California > Minnesota (3, Funny)

Scrameustache (459504) | more than 5 years ago | (#26509755)

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.

Re:California Minnesota (1)

mrmeval (662166) | more than 5 years ago | (#26510255)

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.

Re:California Minnesota (1)

jasontheking (124650) | more than 4 years ago | (#26511025)

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 ?

Re:Why not let a bit through? (2, Insightful)

aplusjimages (939458) | more than 5 years ago | (#26510143)

Would 90% be good enough for night time work?

Re:Why not let a bit through? (1)

Iamthecheese (1264298) | more than 4 years ago | (#26511163)

More than that, it could be a way to reduce any airplane's radar cross-section by 90%. Furthermore a 10% ghost is much better than a 100% picture anywhere.

Re:Why not let a bit through? (1)

Iamthecheese (1264298) | more than 4 years ago | (#26511183)

90% is enough for visual aquisition, laser sighting, and in the future radar sighting to require 1/10th the distance. A 90% drop is massive success.

Funny? (2, Funny)

denzacar (181829) | more than 5 years ago | (#26510299)

I fail to see what is so funny about that.

Re:Why not let a bit through? (1)

LingNoi (1066278) | more than 5 years ago | (#26510235)

It's all a mix up when the told the geeks "makes me an invisible cloak"

They made the cloak invisible meaning that when you put it on you can see under the cloak.

FUUUU (5, Informative)

sakdoctor (1087155) | more than 5 years ago | (#26509099)

Direct link please!
http://www.technologyreview.com/computing/21971/?a=f [technologyreview.com]

Garbage javascript broke for me and the page didn't get past a white page.

Re:FUUUU (-1, Troll)

Anonymous Coward | more than 5 years ago | (#26509173)

It's because KDawson posted the article. But of course KDawson can do no wrong.

Re:FUUUU (5, Funny)

Anonymous Coward | more than 5 years ago | (#26509301)

It's not broke... it's cloaked!

Re:FUUUU (5, Funny)

LearnToSpell (694184) | more than 5 years ago | (#26509919)

Yeah, but that link only rerouted 90% of the light. Here, try this one:

Blindness (4, Insightful)

Tubal-Cain (1289912) | more than 5 years ago | (#26509123)

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?)

Re:Blindness (0)

Anonymous Coward | more than 5 years ago | (#26509253)

Not much use to many people but...

now Daredevil will be unstoppable!!! :o

Re:Blindness (1)

master5o1 (1068594) | more than 5 years ago | (#26510087)

One could leave the cock-pit glass untouched and/or have cameras pointing through. The aircraft would still be hidden well enough.

Re:Blindness (1)

AtomicSnarl (549626) | more than 5 years ago | (#26510273)

Wonderful! Can I get this installed on my personal airborne transportation system? Because then I can truly say: Where is my flying car?

1 to 18 gigahertz (1)

Dr_Banzai (111657) | more than 5 years ago | (#26509131)

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.

Re:1 to 18 gigahertz (2, Funny)

CarpetShark (865376) | more than 5 years ago | (#26509561)

How is 1 to 18 gigahertz a swath as wide as the visual spectrum? It's much wider.

You must be thinking of the 16k visual spectrum. This is referring to the Spectrum 128k.

Re:1 to 18 gigahertz (1)

sortius_nod (1080919) | more than 4 years ago | (#26510905)

That's wavelength, not frequency...

wavelength = length (5, Informative)

Doviende (13523) | more than 5 years ago | (#26509133)

"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>

Re:wavelength = length (5, Insightful)

John Courtland (585609) | more than 5 years ago | (#26509235)

Yeah, but it doesn't matter too much since c is constant. It's easy to calculate wavelength for any given frequency.

Re:wavelength = length (5, Funny)

ZombieRoboNinja (905329) | more than 5 years ago | (#26509461)

Not for those of us who don't live in a vacuum, you insensitive clod!

Re:wavelength = length (2, Funny)

dotancohen (1015143) | more than 5 years ago | (#26509885)

Not for those of us who don't live in a vacuum, you insensitive clod!

C is still constant. C is the speed of light _in_a_vacuum_ not the speed of light in your parent's basement. And by the way I am a clod, you insensitive pedantic.

Re:wavelength = length (1)

beav007 (746004) | more than 4 years ago | (#26511459)

And by the way I am a clod, you insensitive pedant.

There, fixed that for you.

Re:wavelength = length (4, Funny)

Devil's BSD (562630) | more than 5 years ago | (#26509923)

Yeah, I live in a Bose-Einstein condensate, you insensitive clod!

Re:wavelength = length (2, Informative)

edittard (805475) | more than 5 years ago | (#26510513)

Given the radius of a circle you can calculate its area, but that doesn't mean they're the same thing or that you can use them interchangeably. Convertibility is not equivalence, and the article as written is wrong.

Re:wavelength = length (1, Funny)

Anonymous Coward | more than 5 years ago | (#26509903)

Are you suggesting there might be a flaw in one of the articles posted on Slashdot?

Re:wavelength = length (1)

wirelessbuzzers (552513) | more than 5 years ago | (#26510525)

VW bugs are a unit of mass.

invisibility schmisibility (5, Funny)

Anonymous Coward | more than 5 years ago | (#26509143)

Pics or it didn't happen.

Re:invisibility schmisibility (1, Funny)

Anonymous Coward | more than 5 years ago | (#26509657)

Okay, i will post one here using the magicks of the internets!

__________________
||
||
||
||
||
||
|_________________|
See, look how amazing that thing is!
It is so invisible it caused the picture to collapse...

Re:invisibility schmisibility (2, Funny)

JamesTRexx (675890) | more than 5 years ago | (#26509995)

Might as well ask for rule 34...

Re:invisibility schmisibility (2, Funny)

Warll (1211492) | more than 5 years ago | (#26510199)

Here you go
NSFW: http://tinyurl.com/9hn2ba [tinyurl.com]

Re:invisibility schmisibility (0)

Anonymous Coward | more than 5 years ago | (#26510453)

I can't see you, where are you in that picture?

Re:invisibility schmisibility (0)

Anonymous Coward | more than 4 years ago | (#26510969)

perfectly SFW?
oh i see what you did there.
oh i see what i did there. did you see that?
er, uhm, of course you didn't. it was "cloaked." yeah, that's it. "cloaked."

the joke sucked didn't it? sometimes i wish i could cloak all you people.

Re:invisibility schmisibility (0)

Anonymous Coward | more than 4 years ago | (#26511371)

* {display:none}

Happy?

It would not make any difference... (1)

denzacar (181829) | more than 5 years ago | (#26510367)

...to a blind person.

What? Blind people need their porn too.

Re:It would not make any difference... (1)

beav007 (746004) | more than 4 years ago | (#26511477)

Did you call me "Abe Lincoln"?

problems with electronic medical records/privacy (-1, Offtopic)

Anonymous Coward | more than 5 years ago | (#26509179)

one problem is that almost anybody with access to a workstation & email within the system can send your records anywhere. that's not a big deal for most of us, but can be disastrous for some. better days ahead.

Summary is wrong (0)

aepervius (535155) | more than 5 years ago | (#26509183)

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.

The sentence above is wrong (4, Informative)

aepervius (535155) | more than 5 years ago | (#26509221)

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.

Re:The sentence above is wrong (-1, Redundant)

Anonymous Coward | more than 5 years ago | (#26509341)

Why the fuck does everyone have to refer to everything as a fucking swath? Are we all farmers now?

Re:Summary is wrong (2, Insightful)

ResidntGeek (772730) | more than 5 years ago | (#26509457)

unless I missed something or made a terrible error in thinking.

Yep, that's the one. Frequencies should be thought of logarithmically. You can use the musical concept of octaves in this case. 1-18 GHz is about 4.17 octaves, whereas 400-750 THz is about 0.9 octaves.

Bad summary (0, Redundant)

chebucto (992517) | more than 5 years ago | (#26509185)

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.

... After a little wikipeeing, I find: 'A typical human eye will respond to wavelengths in air from about 380 to 750 nm.[1] The corresponding wavelengths in water and other media are reduced by a factor equal to the refractive index. In terms of frequency, this corresponds to a band in the vicinity of 400-790 terahertz' (http://en.wikipedia.org/wiki/Visible_spectrum)

.. 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?

Re:Bad summary (0)

Anonymous Coward | more than 5 years ago | (#26509299)

It's wrong because KDawson posted it, and like all their posts it's grossly erroneous.

Invisibility cloak bullshit again (4, Interesting)

imsabbel (611519) | more than 5 years ago | (#26509199)

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.

Re:Invisibility cloak bullshit again (1, Insightful)

Anonymous Coward | more than 5 years ago | (#26509757)

Quite to the contrary, there are published papers that counter the claim of lenses that can beat the diffraction limit. However, there is no real counter to cloaking.

I don't understand how they can claim that there is no obstacle to a visible light cloak, though. An infrared cloak requires e-beam lithography. How the hell are we supposed to get more resolution than that? Neutron lithography?

Re:Invisibility cloak bullshit again (3, Insightful)

Rorschach1 (174480) | more than 5 years ago | (#26509791)

The 'invisibility cloak' thing is right up there with 'teleportation'. Every time someone manages to 'teleport' the state of a single subatomic particle, we get a bunch of articles likening the process to Star Trek teleporters.

Do ANY of the researchers involved in these things really expect them to have invisibility or teleportation capabilities at macro scales someday? I was under the impression that neither of them had any relevance at larger scales, and while I could be wrong, it seems like the media just can't resist this kind of idiotic hyperbole.

Re:Invisibility cloak bullshit again (0)

Anonymous Coward | more than 4 years ago | (#26511511)

Idiotic hyperbole = more/continued research grants.

How's the American "World Series" for idiotic hyperbole?

At last! (5, Funny)

commodore64_love (1445365) | more than 5 years ago | (#26509207)

Now I can see what happens inside the Girls' dorm!

Giggity-giggity-goo.

Re:At last! (1)

linhares (1241614) | more than 5 years ago | (#26509605)

Now I can see what happens inside the Girls' dorm!

Who needs a cloak for that? [yikers.com]

NOT Invisibility Cloak: RADAR Cloak (3, Interesting)

thorndt (814642) | more than 5 years ago | (#26509227)

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...

Re:NOT Invisibility Cloak: RADAR Cloak (0)

Anonymous Coward | more than 5 years ago | (#26509389)

Radar cloak is easier though. All you have to do is either absorb the energy or dissipate the energy in a direction away from the source. See, with radar a "hole" means nothing is there. The reason for this is that the source is looking for it's own reflection.

Visibility is different because a hole would be quite obvious because it's a passive mechanism. You can't just absorb the energy or redirect it away from the observer (that would make a quite conspicuous black spot).

Re:NOT Invisibility Cloak: RADAR Cloak (0)

Anonymous Coward | more than 4 years ago | (#26510921)

I might well be wrong but aren't you only correct in open areas? Open sea, etc... For example, if there is a ship's radar and within range is an island or something that is visible. Then something that absorbs all the energy moves between the island and the ship. Part of the island disappears from the radar, right?

Re:NOT Invisibility Cloak: RADAR Cloak (1)

Iamthecheese (1264298) | more than 4 years ago | (#26511521)

See, with radar a "hole" means nothing is there.

And with the new chinese technology, for which I can't find a link, that is a problem. They have found a way to look for momentary interruptions in consumer elecronics' signals to find a stealth aircraft. It has already been masively deployed with the excuse that it is used for censorship.

Re:NOT Invisibility Cloak: RADAR Cloak (0)

Anonymous Coward | more than 5 years ago | (#26509661)

If there isn't a replacement for the Stealth Bomber yet, there's likely to be one very soon. I imagine that at least some of this research is being funded by people involved in such projects, given that they have serious money and those wanting to do a Harry Potter can barely afford cinema tickets.

Re:NOT Invisibility Cloak: RADAR Cloak (4, Insightful)

HuskyDog (143220) | more than 4 years ago | (#26511145)

Sigh, here we go again! Radars and optical vision do not work in remotely the same way. Creating invisibility in the two different realms is a completely different problem.

In most vision situations there are two critical factors which don't occur in the great majority of radars. The first is illumination of the target from angles other than the viewing angle (OK, there are bistatic radars, but they are not common) and the other is a background which is illuminated. Try to think about this for just a few moments. Why can't we all make ourselves invisible just by wearing matt black clothing? Well, obviously because we will stand out against the background unless we happen to be standing in front of black wall or wandering around in a coal mine. The whole point of the fictional 'invisibility cloak' is that it works in all circumstances. We can already be invisible in certain carefully controlled environments, that after all is what camouflage is all about.

But, a radar is rather like wandering about in the above mentioned coal mine, or perhaps a dark forest with a miner's lamp fixed to your head. The background is basically black and the illumination comes from the viewing direction. In this scenario, someone dress entirely in black would be effectively invisible. And that is the key point to grasp. In the world or radar we can achieve invisibility simply by making sufficiently 'black' 'paint'. The weird ability of these meta-materials to allow the illumination to pass through the target un-disturbed is of no benefit. Since we don't have a receiver on the other side of the target to detect this energy it isn't relevant. Now, sure, we can all dream up complex bistatic radars which rely on the obscuration of the signal to detect the target, but I remain to be convinced that such a thing can be made sufficiently versatile to be useful.

Can I stress that I am not suggesting the these meta-materials don't have an application in the world of radar. They seem to me to be particularly useful where one wants to remove a fixed object which obscures the view of your radar. For example, consider a radar on a ship. It may well find that in some directions its view is obscured by other parts of the superstructure. If the could cover these other bits of the ship with meta-materials such that the radar pulses could pass 'through' and back again undisturbed, then our radar's field of view would be increased. Such an application would work perfectly well with even the relatively narrow band materials presented previously.

from TFA (4, Funny)

someone1234 (830754) | more than 5 years ago | (#26509303)

"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 :)

A picture is worth a thousand words.... (0)

Anonymous Coward | more than 5 years ago | (#26509333)

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.

Re:A picture is worth a thousand words.... (1)

XcepticZP (1331217) | more than 5 years ago | (#26510687)

Too many people posting AC these days. What were you so scared of when you posted your comment? Seriously, I can understand people posting AC when they want to say something really stupid or outrageous, but not when they post such a insignificant post such as yours!

Re:A picture is worth a thousand words.... (0)

Anonymous Coward | more than 4 years ago | (#26511075)

I am not the GP. I have however been active commenter, practically daily, for a year or so. Many comments modded +5 for various reasons and not a single one modded to negatives yet.

Why do I keep posting AC?

I think it is handy. I can visit /. from the uni., from work, from home, wherever I am and can get some free time. I can check the newest comments and if there are, just quickly reply as AC and if not, I haven't wasted time logging in.

Also, I think that anyone stupid enough to think that anonymous posters automatically post worse content than those who have registered and willing to block all ACs for that can then miss my content too. Their choice.

I also don't think that it should universally be expected for people to post with a nick name. In a place like this, what would anyone do with my nick anyways? Why would I NOT post anonymously?

When I post a comment, I don't want anyone to see "Hey, that comment was posted by that same guy as that other comment...", etc... I want that people read the comment for it's content and weight it accordingly, not because of previous comments by me.

Maybe that gave a bit more enlightenment to the minds of the numerous ACs. I am not behind a nick or registered but I will remember to check my comments for replies as always. ;)

Extraordinary claims require extraordinary proof (1)

religious freak (1005821) | more than 5 years ago | (#26509347)

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.

Re:Extraordinary claims require extraordinary proo (2, Insightful)

fyoder (857358) | more than 5 years ago | (#26509421)

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.

Re:Extraordinary claims require extraordinary proo (1)

beav007 (746004) | more than 4 years ago | (#26511525)

And how would they have done that? Even TFS says that it doesn't work on visible light.

Re:Extraordinary claims require extraordinary proo (0, Redundant)

Talgrath (1061686) | more than 5 years ago | (#26509427)

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.

Re:Extraordinary claims require extraordinary proo (1)

Architect_sasyr (938685) | more than 5 years ago | (#26509503)

"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?

No Photo No Talk! (3, Funny)

sam0737 (648914) | more than 5 years ago | (#26509375)

I look forward to the photo of the prototype.

Re:No Photo No Talk! (0)

Anonymous Coward | more than 5 years ago | (#26509497)

http://starcraft-version1.tripod.com/ic.jpg

Re:No Photo No Talk! (1)

Garrett Fox (970174) | more than 5 years ago | (#26509627)

As part of the hype, one article a while ago showed off such a photo... which was actually a normal photo of a tank, badly Photoshopped to make it look like it was fading to invisibility at one end. That kind of nonsense highlights the level of hype about this project.

Re:No Photo No Talk! (0)

Anonymous Coward | more than 5 years ago | (#26510463)

Sure, here's [forsalehangar4.com] a picture of a hangar with the secret cloaked plane prominently featured.

One color invisibility certainly could be of use. (1)

Lexible (1038928) | more than 5 years ago | (#26509617)

"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.

Re:One color invisibility certainly could be of us (4, Funny)

dotancohen (1015143) | more than 5 years ago | (#26509909)

...and I ain't an engineer.

I bet you've a schoolteacher.

Re:One color invisibility certainly could be of us (5, Informative)

Proteus (1926) | more than 5 years ago | (#26510477)

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 [etymonline.com] ) 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

Re:One color invisibility certainly could be of us (1, Insightful)

Anonymous Coward | more than 4 years ago | (#26511335)

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".

Re:One color invisibility certainly could be of us (1)

vlm (69642) | more than 5 years ago | (#26510049)

"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...

Re:One color invisibility certainly could be of us (0)

Anonymous Coward | more than 5 years ago | (#26510761)

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.

Proof? (0)

Anonymous Coward | more than 5 years ago | (#26509705)

Pics or it didn't happen.

"But a cloak that made an object invisible... (2, Insightful)

Peet42 (904274) | more than 5 years ago | (#26509913)

...to light of only one color would not be of much use."

It would be exceptionally useful if that colour was infra-red.

Why all the work? (2, Informative)

RyoShin (610051) | more than 5 years ago | (#26509915)

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!

Re:Why all the work? (1)

LateArthurDent (1403947) | more than 4 years ago | (#26511329)

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!

The Hitchhiker's Guide to the Galaxy doesn't mention that that Ravenous Bugblatter Beast of Traal posts to slashdot. I shall tell Ford to send in the update :)

no pictures (0)

Anonymous Coward | more than 5 years ago | (#26510345)

Until I see pics of this invisible cloak, I'm not interested!

metamaterials == DoD wasting tax dollars (1, Informative)

Anonymous Coward | more than 5 years ago | (#26510373)

(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.

Re:metamaterials == DoD wasting tax dollars (1)

XcepticZP (1331217) | more than 5 years ago | (#26510717)

And you had to post that as an AC why, exactly?

Is it really all that effective? (0)

Anonymous Coward | more than 5 years ago | (#26510395)

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?

Not much use? Why, I oughta... (1)

Pluvius (734915) | more than 4 years ago | (#26510933)

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

18 GHZ is NOT the width of the visible specturm (5, Informative)

jschimpf (628722) | more than 4 years ago | (#26510937)

Visible light ~5000 - 7000 Angstroms (1X10-9 m)

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

Invisible administrator (0)

Anonymous Coward | more than 4 years ago | (#26511051)

"...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...

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