“He's mad,” said Kemp; “inhuman. He is pure selfishness. He thinks of nothing but his own advantage, his own safety. I have listened to such a story this morning of brutal self-seeking! He has wounded men. He will kill them unless we can prevent him. He will create a panic. Nothing can stop him.” H.G. Wells - The Invisible Man

Invisibility has been a scientific vice list almost from the beginning. The search for invisibility and its cousins like Alchemy and the Fountain of Youth seem like the stuff of science fiction, but it's not just a subject for geeks and freaks. These pursuits, though based in science, are very good at bringing up questions about humanity and our beliefs and morals. What would you be like if you could turn any metal into gold? What would life be like if you could live forever? What would you do if you could not be seen? The world has tried time and time again to provide us with the illusion of in/visibility all with varying success and varying technology. From the Ninja adage of “be one with your surroundings” to the science of optical cameras and reflectors, we will look at two types of invisible technology. One you think works, one you can't believe works and both you don't understand.

Low Tech
The most basic camouflage is the sort worn by those folks out in the battlefield. Concealment is appreciated here. Conventional camouflage clothing has two basic elements that help conceal a person: color and pattern. Camouflage material is colored with dull hues that match the predominant colors of the surrounding environment. The pattern is also very important to the illusion. The reason for this is that the pattern is visually disruptive. The wandering lines of the blotchy camouflage pattern help hide the contour of the body. When you look at a piece of blotchy camouflage in a matching environment, your brain naturally "connects" the lines of the colored blotches with the lines of the trees, ground, leaves and shadows.
Continuity is your brain's best friend in its visual deciphering task. Imagine a stack of 10 Lego's . If all of the Lego's are colored red, you perceive the pile as one unit. But if the bottom 5 Lego's are red and the top five Lego's are blue, you may perceive the pile as two separate units: a stack of blue Lego's on top of a stack of red Lego's. We tend to recognize something as a separate object if it has one continuous color, so a person is much more likely to stand out when wearing a single color than when wearing a jumble of colors. In the jungle, you perceive the jumble of colors in camouflage material as many small things that are component parts of the surrounding foliage.
In this way, blotchy camouflage helps people go undetected even though they are in plain sight. Once you have spotted a camouflaged person, he stands out, and it seems odd that you didn't see him before. This is because your brain is now processing the visual scene differently -- it is looking for a single person. Makes you wonder… why do ninjas wear all black?

High Tech
If you took a camera and put it on your back and hooked it up to a monitor that you held in front of you, people would in a sense be seeing through you, right? Yes! But of course no dip shit would say you were invisible, just some stupid trick that really wasn't that funny especially since you've been trying it at every party you go to with every girl you meet. But wait what if the very clothes you were wearing did what that camera and monitor did? What if your jacket, and not just the large amounts of alcohol, let people see right through you?
That has been the goal of Susumu Tachi's team and their cloaking system. Tachi's cloak, a shiny raincoat, is more gimmick than practical prototype. Nonetheless, from the right angle and under controlled circumstances, it does make a sort of ghost of the wearer. A camera behind the wearer feeds background images through a computer to a projector, which paints them on a jacket as though it were a movie screen. The wearer appears translucent – as long as the person looking at it is at the right angle, and oh yea, as long as it's not too bright outside.

Tachi, who is a professor of computer science and physics at Tokyo University and also the founding head of the Virtual Reality Society of Japan , designed the coat using microscopic reflectors, which act like a movie screen. They can even reflect images when the material is wrinkled . Tachi is uncertain of the technologies practical ramifications but he likes to think that one day well have “glass bottom” airplanes and surgeons who would be able to see through their hands when they are doing surgery. Or, and this is a stretch, it might be used to help those people on the battlefield kill more people.

Conclusion
Why do we want to be in/visible? Without trying to break this all down to Freudian bullshit and whatnot, I present this case study:  (click me)