Invisibility cloak. (inside, a concept that actually might work)

[Lobsang]

I am watching an episode of Science Shack, with Adam Hart Davis. Their task is to make Adam invisible.

One of their ideas was to use a sort of cloak of many mirrors.

Thing is, their version was extremely crude, it was basically a box shape, with Adam inside. When I saw it I though "flipin heck, Adam is gonna stick out like a sore thumb"

But then they tried it. It actually works!!


I should mention that they were in the woods. The idea is that the mirrors simply reflect the surrounding woods in order to look like woods. So the randomness of the view of trees and such is replicated on the mirrors. And as long as the subject stays still they are virtually undetectable.


So I got to thinking. Wouldn't it be feasable to take this further, and invent clothing with lots of tiny mirrors that would allow say a soldier to stand upright in full view, and not be seen (as long as he stays still, and is in a uniformly similar environment)

[JimSox5]

Wow. That's impressive, and simple enough that it just might work. It would have to be a pretty intricate pattern of mirrors, of course, but the concept seems so obvious. I would love to see it done. The problem, though, is how would you see out? Are they one-way mirrors?

[CalMeacham]

Just don't move while you're wearing it, or else one of those facets will probably reflect glints of light right to your enemy' eyes, and you'll be particularly visible.

I think I'd call this camouflage, rather than invisibility.

[NoClueBoy]

Predator

[Electronic Chaos]

I read (sorry, don't remember where, and no cite) somewhere that they're working on a cloaking device where they use lots of fiber-optic cables in a system so that the front shows the back and vice versa. I also read somewhere else (once again, no cite. I should start paying attention more often huh?) about a similar idea using tiny CCDs and then displays inter-woven into the fabric to produce a similar effect. I imagine it actually would look like something out of Predator

[Lobsang]

The problem with the display what's behind idea is that the person you are trying to hide from must be in a very very specific place.

Or the thing being invisible must always face the person it's trying to hide from.

At least with the mirrors idea you are merely simulating what's arround you. Not becoming invisible as such but rather undetectable.

[Electronic Chaos]

Actually the idea is that it would be kind of an alternating pattern between camera and display so that no matter where you're positioned you see what's on the other side.

[Vlad Dracul]

The mirrors would be a problem if your enemy was only a few yards away:

"Hey, there's a guy over there! And he looks JUST LIKE ME!!!"

[OpalCat]

I dunno... seems like you'd look like the Human Disco Ball... disco balls aren't particularly hard to see, after all...

[Lobsang]

That's what I thought when they said what they were going to do.

But how many disco balls have you seen in forests?

Picturing it now - a disco ball would blend in quite well. It would, after all, be the exact same shade of green and brown as it's surroundings.

[green_bladder]

That's pretty neat. But what other environments could it work in? A dense forest, ok; desert? Probably not; the Antarctic? Depends. I think a good one to try out would be underwater, although it may be weird because of the sun rays bouncing off the mirrors.

[Armilla]

I saw the episode in question and the mirror box did indeed work very well in those specific circumstances.

One thing they had to be very careful of was keeping the mirrors vertical. If they tilted back then they would reflect the sky to the observers and he became very obvious. If they tilted down then they'd just reflect the grass/earth ground and he didn't blend in so well.

I gave the matter some thought after the program and it seems to me that Predator-style camouflage is going to be extremely difficult to achieve. It's not just a case of transferring an image from front to back. Each point on the front of the object would have to receive data from multiple points on the back of the object and rebroadcast the light at the same angle.

My solution would be to use colour-shifting cloth linked to a computer that generates a 3D volumetric texture. Current camouflage patterns are known to work pretty well provided you keep very still, so if you could arrange for the pattern to remain fixed while the person moves it'd be even more effective.

If the cloth had some way of knowing where it was then each point could colour itself according to a texture algorithm. It wouldn't make the wearer invisible any more than current static camouflage does, but it would have the immense advantage that the wearer could make movements with a much lower threshold of observability than before.

I'd lay money that active camouflage starts off much more like this than anything to do with projecting specific images or even reflecting the environment.

[Kalhoun]

Heh. There was a Monty Python-esque movie the other night called Erik the Viking or something like that. They had an invisibility cloak that the female lead's mother used to hide gentlemen visitors from her husband. Hilarious.

The mirror thing sounds very cool. But how do you handle light glare?

[Black Train Song]

Here's a problem.

Eventually this invisibility cloak will work it's way into the free market as other military items do. It will come into fashion to own one and wear it to parties and such. What happens when your host goes to retrieve your cloak and can't see the damned thing? Just an empty closet. hmmm.

[NoClueBoy]

My Real Tree™ camo works extremely well. And Real Tree Winter™ is fabulous.

It is extremely hard to identify the humans if positioned well.

[CalMeacham]

I read (sorry, don't remember where, and no cite) somewhere that they're working on a cloaking device where they use lots of fiber-optic cables in a system so that the front shows the back and vice versa. I also read somewhere else (once again, no cite. I should start paying attention more often huh?) about a similar idea using tiny CCDs and then displays inter-woven into the fabric to produce a similar effect. I imagine it actually would look like something out of Predator

Sorry folks, this just won't work, Die Another Day to the contrary notwithstanding. A little thought will show you why.


The closest thing to this idea that looks reasonable is "hiding" sometrhing in the middle of what appears to be a crystal ball, but is actually a ball of clear material with a we--defined gradient index. I know an optics professor who worked on this problem, but without a solution. Another optics professor declared it undoable, but I regard his argument as flawed. I think you can do it, but it would be, at best, a coffeetable curiousity.

[bafaa]

It's not up to Predator standards but they're working on it.
There's a picture in the second link.

http://www.wired.com/news/technology...,58286,00.html
http://www.ananova.com/news/story/sm_747591.html

[CalMeacham]

Sorry, folks -- this stunt may look good from directly in front of the guy, but if you're standing just a little to the side, it will be obvious that you're looking at a screen. The image will distort unless you're looking at it from just the right place. In fact, things won't look right if you're too close or too far away.

The Japanese cloak is an impressive achievement, but it won't give you invisibility.

[Lute Skywatcher]

Originally posted by bafaa
It's not up to Predator standards but they're working on it.

They certainly are.

Military Officer
In the movie "Predator," Arnold Schwarzenegger's character fights a creature that can blend in with the environment. Similarly, chameleon camouflage technology, currently under development at the Soldier Systems Center, could allow soldiers to change the patterns and colors of their uniforms as the environment changes. The technology could include nanomachines and electronically conductive textiles connected to a computer on a carrier.

"The soldier could program a code or take a picture and send it back [to the carrier]," says Dutch De Gay, an engineer at the Soldier Systems Center. "Then the camouflage would change to match the environment." That technology could be available in the next 10 to 15 years.

BBC
Tanks that can repair themselves and change colour on the battlefield are being developed in the US.
A team of researchers based at the New Jersey Institute of Technology, along with the US Army's Armament Research and Development Center are working on the smart machines.

Military vehicles including tanks, trucks helicopters and weapon systems will be covered with a coating that has been embedded with nanotechnology.

The microscopic electromechanical machines - known as nanomachines - will send signals to Army personnel, alerting them if the coating is impaired.

Perhaps most importantly, tanks would turn chameleon, creating instant camouflage and making themselves virtually invisible on the battlefield.

Sounds like the Army is developming the SEP field.

[NoClueBoy]

SEP technology would reguire that you paint the tanks pink with little yellow smilies on them first. Then, apply an SEP field to it and shazzam! it's Somebody Else's Problem™.

[ForgottenLore]

I’ve thought about the concept of a practical invisibility suit quite a bit (my wife would roll her eyes at that statement) and here’s my best low-tech/high-tech effort. I'm sure a lot of other people have come up with pretty much this same idea and discarded it. I was too lazy to actually do research.

The suit is made up of two nested spheres. The inner sphere is large enough for a person to stand up in. The outer one is completely covered with the exposed ends of optic cable strands in the highest density possible. Each strand of cable begins at a point on the surface of the sphere and ends at the point directly opposite. The cabling runs through the space between the spheres. Light entering a cable strand on one side of the sphere is visible from the other side, as if it had traveled in a straight line.

Obvious caveats:

1) The person inside can’t see where they’re going.
2) The resolution is crappy. It won’t stand up to close scrutiny.
3) Light rays from a bright nearby source that strike the end of a strand obliquely would appear to suddenly change direction, making for all kinds of unfortunate distortions.

Oh well, back to the drawing board. No, wait. I haven’t even got to the drawing board yet.

[OpalCat]

Originally posted by CalMeacham
The Japanese cloak is an impressive achievement, but it won't give you invisibility.

I must be not understanding the article, because it seemed that it was saying it was the viewfinder, not the jacket, that was doing the trick:

The photograph was taken through a viewfinder that uses a combination of moving images taken behind the wearer to give a transparent effect.