How To See Through an Invisibility Cloak 201
AMESN writes "Ways to bend light around objects and render them invisible are becoming a major field of scientific study and gaining ground. While no actual invisibility cloak exists yet, researchers are also theorizing on how to beat the perfect cloak."
How to see through an invisibility cloak? (Score:5, Funny)
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How?
Without even trying.
rain (Score:5, Insightful)
No invisibility cloak can hide the fact that it's still a solid object. That or utilize various frequencies of EM as it would be extremely difficult to defeat radar + infared + visible + UV all at the same time.
Re:rain (Score:4, Insightful)
Exactly. Even the vaunted "stealth" technologies of the 1980's and '90s were engineered only towards a certain set of frequencies.
This 'invisibility cloak' could be defeated as easily as using a video camera with "night shot" built in (basically, an infrared emitter on the camera body sends out IR, and the lens picks that up, making it a bit more active than simply taking in whatever it sees). The cloak blocks the IR, so it'll either shine with the reflected waves or will show up as a shadow.
Other ways to defeat it? Talcum powder or other particulates (like rain ferinstance).
'course, I doubt that they could make such a "cloak" anyway, at least insofar as it would still show movement. So unless their 'spy' is really good at standing still, he's still liable to be noticed.
Re:rain (Score:5, Funny)
How would it show movement? AFAIK the cloak should be able to move around and this movement shouldn't be visible to you.
Or do you mean they won't be able to make a flexible cloaking ninja suit that keeps cloaking the ninja as they walk, despite the suit bending? The solution to that, of course, is to roll around inside a giant hamster ball/zorb cloaking device! Watch out... i'll sneak up on you and ROLL YOU TO DEATH.
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So I should Plan on using stairs in my bases to prevent the invisible ninja from attacking.
besides cloaks like this are still usable if the person hiding is standing still. you move when no one is watching and let the patrols pass you by.
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The problem is, with things like sensor networks, there can be no time at all when "no one is watching", at least not near anything interesting.
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The solution to that, of course, is to roll around inside a giant hamster ball/zorb cloaking device! Watch out... i'll sneak up on you and ROLL YOU TO DEATH.
Taking rick-rolling to a whole new level.
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Actually it doesn't, which is the really cool thing about these cloaks. The cloaks are made of a metamaterial for which the refractive index is less than 1, so light travels faster than c in that medium. That's what makes them tricky (but not impossible) to build! The reduced refractive index with respect to the surrounds exactly makes up for the extra distance travelled. It's neat stuff.
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Yep, and even if you got a broadband cloak that worked at all those frequencies, you could still pick it up by a number of ways not mentioned in TFA. You could pick it up with sonar (I guess in principle it could also be an acoustic cloak to beat that too), but you could also change the refractive index of the room. The cloak is designed so that no matter what's in the cloaked region, it appears to have a refractive index of 1 (or whatever the cloak's surrounds are supposed to be). If you change the refr
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You could use a mechanism similar to the linux tee command to send light both to the eyes and the opposite side of the cloak (semi-silvered mirror, and a light amplifier). Besides, two pupil sized holes that can only be seen when the cloaked person is looking directly at you could easily be missed.
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extremely difficult to defeat radar + infared + visible + UV all at the same time
Would it even make sense to become invisible to electromagnetic radiation at so many wavelengths? If someone creates the perfect cloak, how can the person on the inside see whats around them? How do you communicate with anything that is cloaked?
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Oh dear gods, not this again?
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Higher frequencies of sound dissipate rapidly in the air. For something small and moving relatively slowly you would set up a system of standing soundwaves that interfered with its self and once an object disrupts that interfering system, the change becomes detectable.
The easy solution, from the article (Score:4, Informative)
Re:The easy solution, from the article (Score:5, Funny)
But what about when teleporting becomes common use technology? The invisibility cloak would have a teleportation field on top of it. The rock would be just teleported back to the person, and it could have a nifty effect in the invisibility drawing to smooth the effect (ie., instead of just teleporting, the stone would travel at a slightly increased, but still not noticeable speed for a moment)
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With access to arbitrary teleportation technology, why would you need a personal invisibility cloak? You'd be able to teleport in and out when invisibility would be required (unless you're cloaking infrastructure).
You obviously need a bigger teleporter!
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Re:The easy solution, from the article (Score:5, Insightful)
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Much better: throw a handful of flour at it. Hey, it worked well when my D&D party had to deal with invisible stalkers, why not this?
flour? (Score:2, Interesting)
How about flour and water? This reminds me of a joke...
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You can't beat the perfect cloak... (Score:5, Insightful)
If you can, it's not perfect.
The real problem isn't detecting it. It's knowing that you need to be trying to detect it in the first place, and approximately when and in what area.
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The real problem isn't detecting it. It's knowing that you need to be trying to detect it in the first place, and approximately when and in what area.
Monitor for changes in the field of gravity (or magnetic field to use a more mature technology, although I don't know how well that would work in e.g. deep space where there isn't a planetary magnetic field). If there isn't a corresponding change in the visual (or thermal, etc.) appearance of the same area, throw an alert that there's probably a cloaked object
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The question then is, how exactly are you supposed to breathe? If you're out of flux with everything else, where's your air supply gonna come from, unless you wore some kind of rebreather too...
I've always wondered that in Star Trek episodes for example; a crew member gets sent into some slightly out of phase dimension but can still breathe. Where is all this out of phase oxygen coming from?!
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I'd imagine being able to push an unmanned combat aircraft or vehicle into flux to maneuverer to a position of advantage would be one of the most valuable applications.
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If your invisiblity device is 'perfect' then You can't see out.
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Yes you can. You transfer the light after it has hit the person and is going back. So instead of catching the light ray when it hits the invisibility cloak, you catch it when it's leaving the invisibility cloak and transfer on the other side.
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The "catcher" of light at the back of cloaked individual/machine would be visible from the other side.
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Why exactly? You do this on both sides of course.
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Invisibility cloak depends on "bending" the light on the surface of the object. If something "disturbs" the path of light behind perfectly cloaked object, that something is visible (otherwise that wouldn't be an invisibility cloak!).
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That's why we have things like inertial navigation. Used already in comparable scenarios, in submarines for example.
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Somebody has been watching too many reruns of "Kung Fu"...
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You mean, no true Scotsman can beat the perfect cloak.
How about a $5 solution? (Score:2)
A laser pointer, the cheap red kind you can find at any corner store.
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Re:How about a $5 solution? (Score:5, Funny)
> In any case, a well placed pebble should also work as it would bounce off in
> a very obvious way.
Better yet, a well-placed bullet. Just spray bullets in all directions at all times.
Perfect cloak buster - big-ass underground fan (Score:2)
Ala Marilyn Monroe [teennick.com] in "The Seven Year Itch".
TFA (Score:4, Informative)
TFA mentions using charged particles and multiple wavelengths of EM to detect a clocked object. TFA suggests that they were measuring the actual effect on the path of the radiation its self although it should be pointed out that this is quite possibly unnecessary as high energy charged particle entering a solid material undergo an extremely high de-acceleration phase which causes charged particles to emit EM radiation. It's called Bremsstrahlung [wikipedia.org] radiation and could quite possibly be detected.
Why worry? (Score:4, Insightful)
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> A perfect invisibility cloak is also a perfect blindness cloak.
You switch off a small area fifty times a second or so to let your camera look out. A 2cm diameter black spot that is only present a few percent of the time is going to be very hard to spet.
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Meh. Amplify and fork the incoming light -- some goes around to the back of the cloak and out, some reaches your eyes. It's all right there in the manual...
Invisibility (Score:5, Insightful)
An "invisibility cloak" these days doesn't just necessarily apply to the visible light spectrum. The cloak could be a thermal or radar "invisibility" cloak, leaving an object perfectly visible to the naked eye, but invisible on other scans. Penetrating thermal invisibility cloaks might end up more important, because camouflage can take care of visible light from overhead, it's the thermal that's the giveaway.
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"naked" . . . . . . . . . . "Penetrating"
It's rather easy... (Score:5, Funny)
You can drink a blessed potion of see invisible or eat an invisible stalker's corpse while invisible.
What the hell, mods? (Score:2)
This got modded informative? This???
Who the hell here doesn't have a set of D&D books?
</fake-nerd-rage>
ahem, Nethack! (Score:3, Informative)
nt
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You are the lucky winner of my geek certificate!
Wait, does that mean I can get laid now? ;-)
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You can drink a blessed potion of see invisible or eat an invisible stalker's corpse while invisible.
Or just be a monk. You also get the bonus of being incredibly badass.
A really low-tech solution: (Score:2)
When the enemy is invisible... (Score:2)
...only the blind shall see.
I'm sure widespread use invisibility cloaks will lead to increased recruitment of blind people to the military. And that blind kid who does echolocation will be recruited to train a new elite force of super-soldiers.
surprise? (Score:2)
The solution (Score:5, Funny)
Why not simply track displacement? (Score:2, Insightful)
This has always been something that's bothered me about Star Trek. It's well-established that "cloaked" objects, including people, still exist as solid matter and therefore displace whatever space they're occupying. I would think a foolproof means of tracking cloaked objects would simply be to concentrate on whatever it is they're displacing, and look for the telltale starship/person-shaped contour of gaps of nothingness where displacement is occurring. Take the interior decks of a Federation starship for e
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This also bothered me in Stargate: Atlantis the multiple times Atlantis was cloaked to hide it from orbiting Wraith vessels. They know what Atlantis looks like, can't they just scan the ocean's surface and look for the telltale snowflake shape of water displaced by the city?
what bothered me more was the fact they had the capacity to produce anything from thin air with asgard beams, but it never occurred to them to xerox their zpm's or atlantian weapon drones. Don't give me that "unreplicatable" crap either, it's a cop-out which defies even the most liberal sci-fi "suspended disbelief".
Mega geek time... ZPMs aren't just material artifacts, they're a housing for a portal into a pinched off bubble of isolated space-time, from which they draw their zero-point energy. The housing could be replicated, but the bubble is presumably much harder to create.
well... (Score:2, Funny)
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Cloak beating sytem. (Score:2)
Point is if you have a object perfectly cloaked to a good swathe of the electromagnetic spectrum there are still other ways it impinges on it's environment. Accoustics, sound waves (although they may be easy to cloak also) etc.
useful for the cloaker (Score:2)
Presumably, sensors that can penetrate cloaking would be very useful for the operators of the cloaked vehicle, because if no one can see you, you can't see anyone either. In order to see something, light has to be absorbed by the sensors inside the cloak. Since a cloak bends light around the vehicle, the vehicle is flying blind.
Not sure what the fuss is about--sonar should work fine.
Let's keep it real (Score:3, Insightful)
We're getting a bit too excited here. If you read TFA you'll realize how limited this thing is. Many of these designs can only work at one frequency, usually microwave, in one direction, over a very small area, in 2D, and with considerable scattering and attenuation.
That's a heck of a long way from a usable cloaking device. The problems of scattering and attenuation are going to be particularly intractable.
It's unlikely that every one of the many shortcomings can each be improved by the needed factor of 100 or so.
Perfect solution is relative (Score:2)
Silly question (Score:4, Informative)
Use a scrying spell, obviously.
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But you can make listen checks.
Harry Potter reference (Score:2)
How can you detect? put some yelling powder on the floor!
Can the cloak beat the firehose method? (Score:2)
Just spray a firehose around the area, and watch the water bounce off the person or thing with the invisibility cloak? Obviously the water, unlike light, won't warp around the person or thing because it is matter and not photons.
I remember D&D scenarios trying to find an invisible person or thing:
#1 Look for footprints, spread some paint or dust around and let the person step in them and leave a trail.
#2 Throw water, dust, or paint around the room and eventually it will hit the invisible person.
#3 The p
Spychecking (Score:3, Informative)
Well, the easiest way is to have Pyros that Spycheck, or just bump into the Spy by accident.
Wait, you don't mean in Team Fortress 2?
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It seems that the spies' knives always bump into me first :P
--- Mr. DOS
It's easy enough with an Uzi (Score:2)
Spray and pray in the direction from which an invisible enemy might approach. Where there's a blood spray, shoot some more.
Invisible this, bitch!
Detection quite simple (Score:2)
Detecting the presense of an invisibility "cloak" is quite simple in theory. Not much harder for limited areas, but would be difficult for large areas or in highly mobile applications.
Simply put, it's a matter of timing.
If light is being guided around an object then it's taking a longer path than normal. Therefor the amount of time for the light to travel to an item behind the cloaked object would be longer than the time required if the cloak is not there.
As I said. Concept is quite simple.
For limited a
Re:The Possibilities (Score:5, Funny)
The kind I want to go out with. WooHoo; particle launcher!
Re:It's been proved impossible using negative ior (Score:4, Insightful)
I am not sure why people are being so slow to accept this.
Because nothing in world has to be 100% perfect. It just has to work good enough. And maybe later there will be new discoveries that will improve it. That's how technology and science has always worked.
Sure, there will always be ways to get around the invisibility cloak, just like people have ways to get around DRM. But it doesn't make it completely useless or non-working technology.
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"If this thing includes a microscope then the average Windows fanboy can use it to locate their invisible penises."
and
"And you could use it to locate your invisible brain."
Don't you just HATE it when the dentist starts drilling before the Novocaine takes effect? When he hits that freaking NERVE, you can't help responding - sometimes violently. I see someone got YOUR NERVE, LMAO
Re:The Possibilities (Score:4, Funny)
In that scenario aren't you supplying the particle launcher yourself?
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Strangely enough you can also detect pegasi by throwing rocks at them. True story.
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How about a heartbeat sensor from Modern Warfare 2?
Games are a goldmine for these sorts of wacky ideas which just might work.
And instead of side of weapon, add that to the in-front-of-eye see-through monitor. Why we don't actually have such already? The technology is there. But even US army is testing with things [foxnews.com] that will actually take away the whole view from your other eye.
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But be aware of the tactical insertion perk. Sucks to get killed when you're going to check the place and get shot just because some fucker put his tactical insertion there to spawn again on the same camping spot.
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Ahhh, a proper response from a representative from the Pentagon. :)
It's also the same reason aliens will never visit us and say "hi". If you don't understand it (or can't see it), bomb it. :)
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I don't know about you, but I don't usually walk around in city with a flamethrower on.
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You obviously don't live where I do...
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Re:Bahh... the Federation and Dominion figured it (Score:4, Funny)
Thanks, buddy. I suddenly feel much better about myself.
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Technically the tachyon grid was a trap. They purposely left a hole in the net to catch the Romulans. Of course, in the real world, a sensor array of even interplanetary scale is far beyond our capabilities. The sensitivity needs to be extraordinary to detect somethin the size of a ship at such distances.
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Eh, what? Invisibility cloaks work by transferring the light ray over the object inside it. Mirrors work by mirroring the light that hits them. How would this even work?
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Stealth technology, like that used in the B-2 bomber, F-117 nighthawk, and similar aircraft, was never about bending light around the plane. Because RADAR is an active detection technology - that is, it projects radio waves of a particular frequency and waits for a reflection - it was always about reducing the angles at which the radar would reflect.
Plain old metal, no matter how you coat it, is like a pristine mirror for radio waves (the black color was simply because they only ever intended the planes to
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It would be interesting to see a lidar shadow. It would be like someone embossed the world with the shape of the cloaked object's shadow.
However I believe most applications for cloaking involve aircraft so LIDAR probably wouldn't be terribly applicable in that regard.
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I think he just donned the wrong cloak.
and wizard hat.