Beta

Slashdot: News for Nerds

×

Welcome to the Slashdot Beta site -- learn more here. Use the link in the footer or click here to return to the Classic version of Slashdot.

Thank you!

Before you choose to head back to the Classic look of the site, we'd appreciate it if you share your thoughts on the Beta; your feedback is what drives our ongoing development.

Beta is different and we value you taking the time to try it out. Please take a look at the changes we've made in Beta and  learn more about it. Thanks for reading, and for making the site better!

Fatal Flaw Discovered In Invisibility Cloaks

Soulskill posted more than 4 years ago | from the you-cannae-fire-while-cloaked dept.

Science 255

KentuckyFC writes "Carpet cloaks took the world by storm last year because they were the first devices to hide objects at optical frequencies. The idea is that a thin layer of dielectric material placed on a surface can make light look as if it is reflecting off the original surface. In other words, the layer is invisible and anything embedded within it is invisible too. This trick is like hiding something under a carpet, hence the name. Carpet cloaks are relatively easy to make because the dielectric material does not need to be specially constructed to steer light in special ways; physicists call this an isotropic material. Now a group at MIT has shown that isotropic carpet cloaks have a fatal flaw. When viewed at an angle, the carpets don't hide objects at all. Instead, they simply shift their position by about the same distance as they are high. So when viewed from an angle of 45 degrees, an object 0.2 units high is shifted to one side by a distance of 0.15 units, says the team. That's a serious limitation for carpet cloaks."

cancel ×

255 comments

bummer (2, Insightful)

Anonymous Coward | more than 4 years ago | (#31902118)

bummer.

The fatal flaw is: (2, Insightful)

Anonymous Coward | more than 4 years ago | (#31902146)

They DON'T WORK!

Re:The fatal flaw is: (4, Funny)

Locke2005 (849178) | more than 4 years ago | (#31902216)

I can't see how they could work.

Re:The fatal flaw is: (3, Informative)

ryantmer (1748734) | more than 4 years ago | (#31902460)

I am amused at the correlation between your comment and your sig. Well done, sir.

Re:The fatal flaw is: (1)

eltaco (1311561) | more than 4 years ago | (#31902546)

"Invisibility cloak?!? Ha! I'll believe it when I see it!"
so, do you believe it now that you can kinda see it from an angle? :-)

Re:The fatal flaw is: (4, Funny)

exley (221867) | more than 4 years ago | (#31902368)

No, the fatal flaw is that a cloaked object moving at warp speed emits a slight subspace variance. Adversaries performing an antiproton scan may also be a problem.

Re:The fatal flaw is: (4, Funny)

Yvan256 (722131) | more than 4 years ago | (#31902400)

What if we modify the phase variance?

Re:The fatal flaw is: (5, Funny)

Anonymous Coward | more than 4 years ago | (#31902564)

What if we modify the phase variance?

yeah, as long as we randomly modulate the shield frequencies, reverse the polarity of the heisenberg compensators, and amplify the transporter buffers... we should be good to go. Earl Grey tea never tasted so good.

Re:The fatal flaw is: (2)

pedrop357 (681672) | more than 4 years ago | (#31902886)

Don't forget to note, and share with others, the differences between self-sealing stem bolts and warp matrix flux capacitors.

So what?! (0)

Provocateur (133110) | more than 4 years ago | (#31902420)

The Predator is one bad-ass early adopter, and pre-orders the first batch exclusively for his squadron.

Re:The fatal flaw is: (2, Insightful)

corbettw (214229) | more than 4 years ago | (#31902528)

I thought the problem was the expulsion of highly-charged particles? Plasma, or whatever it's called. After all, the thing's gotta have a tailpipe.

Re:bummer (5, Funny)

Jason Earl (1894) | more than 4 years ago | (#31902328)

They should be working on a "Somebody Else's Problem" field. I hear that this is much easier than trying to much around with physics.

Re:bummer (3, Insightful)

maxwell demon (590494) | more than 4 years ago | (#31902532)

They did. Then they switched it on, and ever since they are seeking the device.

Re:bummer (4, Funny)

halivar (535827) | more than 4 years ago | (#31902828)

Unfortunately, every member of the search team is slacking off, assuming someone else is looking for it.

Re:bummer (1)

vrmlguy (120854) | more than 4 years ago | (#31902510)

Still, it's better than a fatal flaw that causes users to spontaneously combust.

Re:bummer (1)

PIBM (588930) | more than 4 years ago | (#31902882)

At least that would have been funny!

Re:bummer (1)

Spaham (634471) | more than 4 years ago | (#31902530)

darn

Cheer up (5, Informative)

Moraelin (679338) | more than 4 years ago | (#31902620)

Well, cheer up. It might still mean that the Romulan's weapons hit some nearby console when they think they're targeting the warp core. Of course, it would be better if they didn't hit anything at all, but I'm affraid that the law that for each hit a console must explode in a shower of sparks and send some ensign flying across the room is more immutable than the laws of refraction ;)

Wrong Cloak (5, Insightful)

LaminatorX (410794) | more than 4 years ago | (#31902122)

So what they're saying is it's more of a Cloak of Displacement? While less stealthy, I think that's actually better odds of avoiding the hit than the penalty for attacking an invisible opponent.

Re:Wrong Cloak (4, Funny)

meerling (1487879) | more than 4 years ago | (#31902188)

Better a D&D reference than another of the endless Harry Potter ones...

Re:Wrong Cloak (1)

SnarfQuest (469614) | more than 4 years ago | (#31902270)

A hairy what? The last part of your sentence seems distorted somehow.

Re:Wrong Cloak (0)

Anonymous Coward | more than 4 years ago | (#31902376)

Oh just shut up! Langlock!

Re:Wrong Cloak (0, Offtopic)

halivar (535827) | more than 4 years ago | (#31902864)

!!!SEID NILTSIAR

I guess? (3, Insightful)

Monkeedude1212 (1560403) | more than 4 years ago | (#31902124)

Yeah - you aren't invisible, but wouldn't that still make the tracking missile miss you?

Re:I guess? (1)

Thanatos81 (1305243) | more than 4 years ago | (#31902300)

That depends. If the cloaks only affect visible light: No, the tracking missile would not miss you. Most missile guidance systems are still based on RADAR or IR, which do not use visible light.

Re:I guess? (0)

Anonymous Coward | more than 4 years ago | (#31902382)

That depends. If the cloaks only affect visible light: No, the tracking missile would not miss you. Most missile guidance systems are still based on RADAR or IR, which do not use visible light.

I'm willing to take my chances that Natalie Portman does not have tracking missiles in her bedroom.

Re:I guess? (1)

Monkeedude1212 (1560403) | more than 4 years ago | (#31902518)

I assumed this applied to most of the Electromagnetic spectrum, or is it just visible light, do they say? I always naturally assume IR included in these kinds of things, since it is so close to visible light on the spectrum.

Radar on the other hand, I thought we had reliable countermeasures for, like jamming? or have I been watching too much Hollywood

Re:I guess? (1)

Mr. Foogle (253554) | more than 4 years ago | (#31902334)

If it's optically tracked, sure. You might be out of luck if the operator is using IR.

Re:I guess? (1)

interval1066 (668936) | more than 4 years ago | (#31902394)

That's what I'm saying. Shifting the apparent location of a target is almost as good.

Re:I guess? (1)

badboy_tw2002 (524611) | more than 4 years ago | (#31902558)

I guess if it shifted it a few hundred feet. A tank sitting right next to where the cruise missile hit is about the same as the missile hitting the tank itself.

Re:I guess? (1)

Weedhopper (168515) | more than 4 years ago | (#31902786)

No, it's not. Not unless the warhead is nuclear.

A near miss against sufficient armor is a miss. That's half the reason the armor is there in the first place.

Re:I guess? (4, Interesting)

Arancaytar (966377) | more than 4 years ago | (#31902462)

Depends on the size of the missile...

Re:I guess? (1)

MartinSchou (1360093) | more than 4 years ago | (#31902892)

I think you'll find it's less about the size of the missile and more about the yield of the warhead.

One of the advantages to 10+ Mton nuclear warheads, is that you don't need to be very precise

Re:I guess? (0)

Anonymous Coward | more than 4 years ago | (#31902484)

A light displacing cloak defeating a heat seeking missile?

Re:I guess? (1)

wizardforce (1005805) | more than 4 years ago | (#31902812)

Maybe so but a broad spray of shrapnel and bullets won't. Even rain could defeat a cloak unless the rain goes right through it without resistence.

Re:I guess? (1)

SwordsmanLuke (1083699) | more than 4 years ago | (#31902894)

Two words. Splash. Damage.

Invisible post (1, Funny)

Anonymous Coward | more than 4 years ago | (#31902130)

You can't see this post, oh wait, maybe you can...

Re:Invisible post (2, Funny)

gyrogeerloose (849181) | more than 4 years ago | (#31902594)

You can't see this post, oh wait, maybe you can...

Yes, I can, but 1.5 posts below where it actually is.

Well... (2, Insightful)

the_one_wesp (1785252) | more than 4 years ago | (#31902132)

saw that problem coming.

Military Applications (5, Interesting)

jornak (1377831) | more than 4 years ago | (#31902136)

I'm sure a carpet cloak like this would have military applications, and in a desert environment like the Middle East, people aren't going to notice you unless they're close to you.

A sniper on a ridge covered with one of these babies is still going to do the job.

Re:Military Applications (1)

Slotty (562298) | more than 4 years ago | (#31902186)

Why use snipers when you can just launch a cruise missle and destroy the entire town?

I'm pretty certain they considered it considerable collateral damage in Iraq

Re:Military Applications (1, Informative)

UziBeatle (695886) | more than 4 years ago | (#31902256)

  It's why I say listen to Ripley you dolts. (situational variance)

  As she said, "Just nuke the site from orbit, just to be sure."

  Problem furking solved. Move along now, nothing to see here SOON.

  Use the maximum force possible to cover up errors.

Re:Military Applications (0)

Anonymous Coward | more than 4 years ago | (#31902208)

But would the sniper do the job better in this than he would in a standard Ghillie suit?

Re:Military Applications (1)

tmosley (996283) | more than 4 years ago | (#31902296)

You COULD do both. Should they happen to see you, they will see you in the wrong spot, and you can take them all out in quick succession no problem.

Re:Military Applications (1)

PIBM (588930) | more than 4 years ago | (#31902920)

Unless the enemy sniper fails at shooting and randomly hit you =)

Re:Military Applications (1)

Shadow of Eternity (795165) | more than 4 years ago | (#31902212)

So if I understand this right TFA says that these cloaks just render something as appearing where it isn't rather than completely invisible when viewed from various angles?

If so that's still got the possibility of being pretty bloody useful.

Re:Military Applications (1)

mwvdlee (775178) | more than 4 years ago | (#31902406)

At least it could hide things from satelites, since they don't look down at any significant angle.

Re:Military Applications (1)

Fred_A (10934) | more than 4 years ago | (#31902508)

I'm sure a carpet cloak like this would have military applications

Sure, if you have soldiers the size of a pinhead.

But then, remember that all the jihadists have to do is move sideways a bit and "ha ha, we can see your pinhead, you silly infidel !"

Soo.... (4, Insightful)

Some.Net(Guy) (1733146) | more than 4 years ago | (#31902150)

When they were creating these cloaks, they didn't think to look at it from other angles than just straight on? Seriously? That's the equivalent of "it works on my machine."

Re:Soo.... (4, Insightful)

e2d2 (115622) | more than 4 years ago | (#31902262)

They're making things invisible. It's kind of hard. So cut them a break? It's not like it's been done before and they just half-assed it after all.

It won't protect... (0)

Anonymous Coward | more than 4 years ago | (#31902156)

items in your inventory from getting wet.

Finally!!! (3, Funny)

Locke2005 (849178) | more than 4 years ago | (#31902164)

At last, my sig is actually appropriate for a slashdot story!

Re:Finally!!! (0, Redundant)

Monkeedude1212 (1560403) | more than 4 years ago | (#31902202)

You know, they mentioned Invisibility cloaks a few weeks ago and I managed to get a +1 informative by mentioning your signature, asking if it was yours or someone elses since I couldn't remember.

Re:Finally!!! (0, Insightful)

Anonymous Coward | more than 4 years ago | (#31902502)

And now you are hoping for an +1 informative/funny mod by referring to you post made few weeks ago, that referred to the signature of the GP and asked if it was his or someone elses signature, since you couldnt remember.

Am I right?

Re:Finally!!! (1)

Apocryphos (1222870) | more than 4 years ago | (#31902742)

I'll only say that at the least you're not wrong.

I see no sig... (2, Funny)

foo1752 (555890) | more than 4 years ago | (#31902674)

I'm sorry, my "Disable sigs" preference has completely cloaked your sig.

Re:I see no sig... (2, Funny)

pedrop357 (681672) | more than 4 years ago | (#31902918)

Adjust your viewing angle

So.. (0)

Anonymous Coward | more than 4 years ago | (#31902172)

it took them that long to look at the carpet from a different angle?

Fatal Flaw Discovered In Invisibility Cloaks (3, Funny)

Anonymous Coward | more than 4 years ago | (#31902178)

You could bump into the invisible object.

That's not a flaw... (1)

Unka Willbur (1771596) | more than 4 years ago | (#31902180)

It's an undocumented feature! I mean, offsetting my apparent position could be as useful as making me disappear entirely!

Re:That's not a flaw... (1, Insightful)

Anonymous Coward | more than 4 years ago | (#31902454)

offsetting my apparent position could be as useful as making me disappear entirely!

Not when you are trying to use it to sneak around in the women's locker room.

Have they considered... (0)

Microsift (223381) | more than 4 years ago | (#31902190)

Magic?

Re:Have they considered... (2, Insightful)

Genrou (600910) | more than 4 years ago | (#31902570)

No. But they considered a sufficiently advanced technology.

Props to Soulskill (2, Insightful)

magsol (1406749) | more than 4 years ago | (#31902240)

...for making a Wing Commander reference (from the books, not the horrific movie that by coincidence has the same name) in the "department" byline for this story.

Re:Props to Soulskill (1)

gstoddart (321705) | more than 4 years ago | (#31902322)

...for making a Wing Commander reference (from the books, not the horrific movie that by coincidence has the same name) in the "department" byline for this story.

Wow, given the implied Scottish accent in "you-cannae-fire-while-cloaked", I actually would have thought that was a reference to Scotty from Star Trek.

Apparently, I'd have been wrong. Of course, one can argue that any Scottish accent in Sci Fi after Scotty is, by definition, an homage to the great engineer -- and, for purposes of discussion, I believe I will. :-P

Cheers

Re:Props to Soulskill (1)

Enderandrew (866215) | more than 4 years ago | (#31902664)

There were Wing Commander books? I'm only familiar with the Wing Commander video games that were the basis for the movie.

Pictures (4, Informative)

brianleb321 (1331523) | more than 4 years ago | (#31902260)

I demand more pictures of invisibility cloaks in articles about invisibility cloaks. Theory be damned.

invisiball (1)

escay (923320) | more than 4 years ago | (#31902266)

but will the cloaks still work when shaped like small* spheres?

*small where you are almost looking radial from any direction

Predator (0)

Anonymous Coward | more than 4 years ago | (#31902282)

So it'll look a bit like the Predator's invisibility? (Or the Stealth camo from Metal Gear Solid?)

Question (0)

Anonymous Coward | more than 4 years ago | (#31902308)

Could this stiff be used to hide objects from satellites? I would think satellites would have more restricted options regarding the angle they view something at. Or am I wrong?

Doctor Who knew all this stuff already... (1)

C-base (1780086) | more than 4 years ago | (#31902312)

If you have something to hide, make it look like a telephone booth, and no-one will be suspicious.

Re:Doctor Who knew all this stuff already... (1, Insightful)

Anonymous Coward | more than 4 years ago | (#31902418)

Unfortunately everyone has a mobile phone nowadays, so they -do- stand out (letterboxes too). But if you don't mind the risk of getting blown up for your valuable insides, you could still dress up as an ATM.

What happens... (2, Interesting)

d1r3lnd (1743112) | more than 4 years ago | (#31902314)

What happens when you layer them? I mean, if you overlap a bunch of these invisibility carpets, what would you end up looking at?

Re:What happens... (1)

genghisjahn (1344927) | more than 4 years ago | (#31902434)

It's invisibility cloaks all the way down...

Shoot to miss (3, Interesting)

Mr. Foogle (253554) | more than 4 years ago | (#31902318)

So when viewed from an angle of 45 degrees, an object 0.2 units high is shifted to one side by a distance of 0.15 units, says the team. That's a serious limitation for carpet cloaks.

Maybe. But it would be a great way for soldiers to conceal themselves from aimed rifle fire.

Re:Shoot to miss (2, Insightful)

PinkFreud (51474) | more than 4 years ago | (#31902736)

That might work. A 6 ft soldier would appear to be displaced by about 4.5', if that ratio holds.

Re:Shoot to miss (0)

Anonymous Coward | more than 4 years ago | (#31902826)

Yes, but if the enemy shoots on your shifted image, he'll hit your carpet cloak. And most electronics don't like bulletholes.

All over the world (0)

Anonymous Coward | more than 4 years ago | (#31902320)

From TFA:

Zhang and co go on to prove their assertion by tracing a ray that passes through the kind of isotropic carpet cloak that Pendry suggested. What they've discovered will shock carpet cloakers all over the world.

Yeah, all over the world.... uhm, all three of them. (Emphasis mine)

Re:All over the world (3, Insightful)

TheMeuge (645043) | more than 4 years ago | (#31902372)

From TFA:

Zhang and co go on to prove their assertion by tracing a ray that passes through the kind of isotropic carpet cloak that Pendry suggested. What they've discovered will shock carpet cloakers all over the world.

Yeah, all over the world.... uhm, all three of them. (Emphasis mine)

The three that YOU CAN SEE...

Oh, well.... (1)

tpstigers (1075021) | more than 4 years ago | (#31902378)

guess I'll have to postpone that trip to Mordor.

Re:Oh, well.... (0)

Anonymous Coward | more than 4 years ago | (#31902898)

It doesn't hide you, the material itself is invisible.

Disappointing (3, Interesting)

Mursk (928595) | more than 4 years ago | (#31902380)

I don't know about you, but when I hear the phrase "fatal flaw," I really expect something a little more, I don't know... hilarious.

Re:Disappointing (1)

Yvan256 (722131) | more than 4 years ago | (#31902486)

If you look at the invisibility cloak the wrong way, it kills you!

Re:Disappointing (1)

hoggoth (414195) | more than 4 years ago | (#31902520)

> If you look at the invisibility cloak the wrong way, it kills you!

Those are Soviet invisibility cloaks.

Re:Disappointing (1)

nickspoon (1070240) | more than 4 years ago | (#31902618)

"We have discovered that when applied to humans, all it does is make your clothes invisible!" said one scientist at MIT, before winking and disappearing into a nightclub.

They're right! (1)

pclminion (145572) | more than 4 years ago | (#31902424)

When I take two steps to the right, all of a sudden all I see are AC posts modded down to -1. It appears the Slashdot moderation system is angle-dependent! I'm sure to win the Nobel for this.

Thanks for what everyone already suspects or knows (1)

kaputtfurleben (818568) | more than 4 years ago | (#31902458)

I don't think anyone has ever thought or suspected that the 'invisibility cloaks' of today are in any way without flaws.

So you're saying... (2, Insightful)

eegad (588763) | more than 4 years ago | (#31902474)

It took a team from MIT to walk to the side of the object, look at the object and report that the object could be seen? I think this cloak managed to hide something other than the object....

0.2 units high by 0.15 units? (3, Insightful)

Posting=!Working (197779) | more than 4 years ago | (#31902534)

I mean, I know we all understand it, but if you're giving an example, why use unitless decimals when you can use integers and tangible concepts? Why not just say it would displace a 4 meter tall truck by 3 meters instead of 0.2 units tall object by 0.15 units?

Re:0.2 units high by 0.15 units? (2, Interesting)

Mursk (928595) | more than 4 years ago | (#31902770)

What is that in Libraries of Congress?

ever since they discoverd this theoretical flaw (2, Funny)

circletimessquare (444983) | more than 4 years ago | (#31902562)

in a theoretical device, i have been theoretically impressed

Anonymous Coward (0)

Anonymous Coward | more than 4 years ago | (#31902586)

only a romulan would use such technology. and (obviously) their hearts are not *truly* klingon.

There is a fatal flaw... (0)

Anonymous Coward | more than 4 years ago | (#31902600)

They aren`t invisible at all.

The Fatal Flaw (1)

NotQuiteReal (608241) | more than 4 years ago | (#31902604)

You will still get pushed off the subway platform by the crowd, or hit by a bus that doesn't see you!

Re:The Fatal Flaw (0)

Anonymous Coward | more than 4 years ago | (#31902850)

Sorry to go off-topic. But regarding your signature - is it true that there were 94 billion human beings born before us?

two obvious solutions (1)

ffflala (793437) | more than 4 years ago | (#31902652)

1. Roll up the carpet.
2. Put the object in a carpet, then put the carpeted object in another, slightly angled carpet, then put THAT into yet another slightly more angled carpet, and that entire batch into still yet another, even more slightly angled carpet, etc, until all angles are covered.

Invisibility Disadvantage (1)

hduff (570443) | more than 4 years ago | (#31902810)

Remember the "Wonder Woman - Invisible Man - Superman Encounter"?

I'll pass on the cloak in any event, thanks.

I'm suspicious... (1)

mea37 (1201159) | more than 4 years ago | (#31902906)

For all the talk of cloaking technologies I hear around here, this is the first I've heard of this one. Sure, I'm not an expert in the field, but if this "took the world by storm" last year, I'm surprised no news stories ever reached me.

Most suspicious, though, are the references to this as a technology for which practical devices have been built. The effect described in TFA is something you could see empirically if you had a working model; you don't need someone to draw a diagram showing the course of a light ray for that. Out of context, such a diagram seems quite useless really.

So TFA talks about evolution of the idea into a practical device in a matter of months, and there's a link... but that just leads to another vague article that says two teams have built something, but doesn't show it. It, in turn, has external references to what might be academic papers... and after reading those abstracts I gave up.

Sounds like a bunch of hype to drum up interest (funding?) in research. You've claimed there's a working device; indicate the scale on which it works, and show a video, complete with explanation of why this "fatal flaw" is or isn't obviously visible in the video, and then we'll talk.

There must be lots (1)

bugs2squash (1132591) | more than 4 years ago | (#31902922)

of circumstances where any viewpoint other than roughly straight on is impractical - for example looking at someone through a tunnel, or someone a long way off through a telescope where to get any viewpoint from a significantly different angle would take a lot of walking. Presumably it works just fine then.
Load More Comments
Slashdot Account

Need an Account?

Forgot your password?

Don't worry, we never post anything without your permission.

Submission Text Formatting Tips

We support a small subset of HTML, namely these tags:

  • b
  • i
  • p
  • br
  • a
  • ol
  • ul
  • li
  • dl
  • dt
  • dd
  • em
  • strong
  • tt
  • blockquote
  • div
  • quote
  • ecode

"ecode" can be used for code snippets, for example:

<ecode>    while(1) { do_something(); } </ecode>
Create a Slashdot Account

Loading...