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Fatal Flaw Discovered In Invisibility Cloaks
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."
bummer.
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.
Yeah - you aren't invisible, but wouldn't that still make the tracking missile miss you?
You can't see this post, oh wait, maybe you can...
saw that problem coming.
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.
They DON'T WORK!
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."
items in your inventory from getting wet.
At last, my sig is actually appropriate for a slashdot story!
I've abandoned my search for truth; now I'm just looking for some useful delusions.
it took them that long to look at the carpet from a different angle?
You could bump into the invisible object.
It's an undocumented feature! I mean, offsetting my apparent position could be as useful as making me disappear entirely!
"Remember when I said I would never lie? Well, that was the first time."
Magic?
My other sig is extremely clever...
...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.
"I'd just like to emphasise that taking a million years isn't a metaphor here..." -Rich Bradshaw
I demand more pictures of invisibility cloaks in articles about invisibility cloaks. Theory be damned.
Please stop pluralizing words with an apostrophe. That is not what it is there for.
but will the cloaks still work when shaped like small* spheres?
*small where you are almost looking radial from any direction
My sig has been answered.
So it'll look a bit like the Predator's invisibility? (Or the Stealth camo from Metal Gear Solid?)
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?
If you have something to hide, make it look like a telephone booth, and no-one will be suspicious.
What happens when you layer them? I mean, if you overlap a bunch of these invisibility carpets, what would you end up looking at?
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.
Display some adaptability.
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)
guess I'll have to postpone that trip to Mordor.
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.
"This thing does science so hard, you say, 'I've never seen that much science.'" -Sam
The Predator is one bad-ass early adopter, and pre-orders the first batch exclusively for his squadron.
WARNING: Smartphones have side effects--most of them undocumented.
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.
I don't think anyone has ever thought or suspected that the 'invisibility cloaks' of today are in any way without flaws.
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....
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?
This sentence no verb.
in a theoretical device, i have been theoretically impressed
intellectual property law is philosophically incoherent. it is your moral duty to ignore it or sabotage it
only a romulan would use such technology. and (obviously) their hearts are not *truly* klingon.
They aren`t invisible at all.
You will still get pushed off the subway platform by the crowd, or hit by a bus that doesn't see you!
This issue is a bit more complicated than you think.
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 ;)
A polar bear is a cartesian bear after a coordinate transform.
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.
I'm sorry, my "Disable sigs" preference has completely cloaked your sig.
Remember the "Wonder Woman - Invisible Man - Superman Encounter"?
I'll pass on the cloak in any event, thanks.
"I believe in Karma. That means I can do bad things to people all day long and I assume they deserve it." : Dogbert
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.
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.
Nullius in verba
So independent reseachers have now "discovered" that it doesn't work when you look at things at an angle.
And the guys originally developing the cloak never even though of that???
So much for testing your ideas...
Throw dust or water on it. There, was that so hard? :)
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.
Now see here... If the polarity of anything is to be reversed, then clearly we should start with the neutron flow...
Bow-ties are cool.
rotating mirror mount?
... Although, if TFA is to be believed, it won't appear to be.
Conscience is the inner voice which warns us that someone may be looking.
... wouldn't these "invisibility cloaks" be easily defeated with thermal detection equipment?
The displacement isn't as useful as everyone thinks. Anything that is wider than it is tall will still get hit by any shot that's near center or to the correct side of the displacement, and some shots that would have missed will be hits. Actually anything whose height to width ratio is 4:3 or lower will still get hit. That covers a lot of the military equipment you'd want to hide - tanks, planes, ships, most buildings, most vehicles, anyone not standing up, etc.
This sentence no verb.
I don't think anyone has ever thought or suspected that the 'invisibility cloaks' of today are in any way without flaws.
I don't know. I mean, I haven't seen them, so clearly they're working...
Bow-ties are cool.
"When viewed at an angle, the carpets don't hide objects at all."
Sounds to me like a real-life SEP field...
they sold that technology to the monsters in Riddick's movie
I've looked all over youtube and all I've found is rendered examples of how it bends the light.... I want to see how this works in real life!
Best I've found: http://www.youtube.com/watch?v=WeiFcJC7diA
Please don't use anonymity as an excuse for being a butt head >:(
The point of any stealthy device is not evade detection forever, it is to evade detection long enough to achieve tactical surprise. It's a time making device, whereas enemy detection systems are time stealing devices. If you have an invisibility cloak with a bad vector, you can still develop a strategy to use it in a vector that is good. In fact, any Tom Clancy fan (I date myself), knows that this is how American stealth aircraft work. Its not just the technology, but the way it is used.
This is my sig.
or a curtain
or a box
or a "hey! look over there!"
or a towel...
Yep you are right ! ;)
In fact it is just like playing Crysis; It took me a while to understand why other on-line players in Crysis War could still see me (and shoot at me) when I was cloaked when all the IA animated Koreans in Crysis would do is say: "have you seen that?" without barely ever firing at me ;-))
The fact is, you can see cloaked individuals, they are just much harder to see, especially if no shade is projected on the ground.
See ? Fiction meets realty...
If they can't make you totally invisible in a fictional game, how could we think it's doable in realty ? ;-))
Everything I write is lies, read between the lines.
What will the sniper see, looking out from behind this device. Unless the next HP book spawns a form of lightless vision, light transmitted by the target has to strike the eye of the sniper for the murder to occur. What happens to light when it strikes the imaginary carpet? It might be better to convince your victims to wear them, then they couldn't see you coming....
I suppose we'll never see an invisibility cloak. **groan**
And I wasn't supposed to, eh? ;)
If Google really cared they would fix Android Chrome to reflow text, instead of discriminating
"relatively easy to make" yet all we have is some lousy drawing.
The problem is that the "cloak" is 2d. Use this tech to make it so.
http://www.physorg.com/news188550483.html
Then the viewer sees 3d invisible.
It's a small thermal exhaust port.
Many Bothans died to bring us the information that farting while wearing an invisibility cloak will give away your location.
Carpet cloaks are relatively easy to make because the dielectric material does not need to be specially constructed to steer light in special ways
how is it a "flaw" to not have a feature it was designed to not have?
...and bend our collective will towards something useful like Boots of Speed or Gauntlets of Ogre Power.
So they learned you can see the filament THROUGH the light-bulb? utterly amazing
Duh? Invis cloaks is pure sci-fi, they do not exist in the real world. This flaw is one of like 100s that prevent invis cloaks like the one in harry potter from existing in the real world. Move on, try something else.
You are falling right into the trap. Of course they want you to look at this cloak so that you don't notice the other one. The story is clearly part of a larger misdirection strategy. . .
"Lost time is not found again."
Just put another invisibility cloak over the displaced object
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 ;)
Deploy a security team on the bridge.
Donte Alistair Anderson Roberts - hi son!
Karma: Chameleon
Your Harpoon and Cruise missiles are still relying on a direct hit to be a "ship killer". (Most) ships do not have significant levels of armour and a 1000lb projective containing HE and rocket fuel exploding within the penetrated hull is going to ruin everyones day.
Same thing applies though, if it misses, it just goes "splash"
Donte Alistair Anderson Roberts - hi son!
Karma: Chameleon
Rotate the carpet cloak so the duplicate image is underground!
Donte Alistair Anderson Roberts - hi son!
Karma: Chameleon
What about looking for other projects ?
I'm particularly fond of Instant Portable Holes rather than invisible cloaks.
What is best in life? To crush your enemies, to see them driven before you and to hear the lamentations of their women.
sooo, does it mean that when standing beside a large rock, it will shift my image behind the rock ? :-)
I skimmed both articles, and something bothers me. The line "when viewed from an angle of 45 degrees". Um, isn't that step two in determining if said cloak works? I mean, "Looks invisible for this angle, let's look at it from another angle to see if its still invisible".
My guess is that they are not cloaking something that large. Measurements are given as "0.2 units" and "0.15 units". The original article stated that they were covering "a bump". My guess is that Harry Potter is not wodering around in one of these.
I'm not sure why this is even a "discovery." I thought it was very well known that existing "invisibility cloaks" only worked over one frequency of light, traveling in one direction.
If it's for-profit but free, you're not the customer -- you're the product (e.g., the Slashdot Beta's "audience").
It helps if you wear burkenstocks.
OMG!!!! I can finally ditch this crappy +1 Cloak of protection now...
Read about it here:
http://gay-bible.org/write/2_cloak.htm
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.
Is that a joke ? What is the use of asking "a group at MIT" to "show" what is obvious even for a 12-years old ?