LONDON (Reuters) - It's unlikely to occur by swallowing a pill or donning a special cloak, but invisibility could be possible in the not too distant future, according to research published on Monday.

Harry Potter accomplished it with his magic cloak. H.G. Wells' Invisible Man swallowed a substance that made him transparent.

But Dr Ulf Leonhardt, a theoretical physicist at St Andrews University in Scotland, believes the most plausible example is the Invisible Woman, one of the Marvel Comics superheroes in the "Fantastic Four."

"She guides light around her using a force field in this cartoon. This is what could be done in practice," Leonhardt told Reuters in an interview. "That comes closest to what engineers will probably be able to do in the future."

Invisibility is an optical illusion that the object or person is not there. Leonhardt uses the example of water circling around a stone. The water flows in, swirls around the stone and then leaves as if nothing was there.

"If you replace the water with light then you would not see that there was something present because the light is guided around the person or object. You would see the light coming from the scenery behind as if there was nothing in front," he said.

In the research published in the New Journal of Physics, Leonhardt described the physics of theoretical devices that could create invisibility. It is a follow-up paper to an earlier study published in the journal Science.

"What the Invisible Woman does is curve space around herself to bend light. What these devices would do is to mimic that curved space," he said.

Although the devices are still theoretical, Leonhardt said scientists are making advances in metamaterials -- artificial materials with unusual properties that could be used to make invisibility devices.

"There are advances being made in metamaterials that mean the first devices will probably be used for bending radar waves or the electromagnetic waves used by mobile phones," he said.

The devices could be used as protection mechanisms so the radiation emitted from mobile phones does not penetrate electronic equipment. It is guided around it.

"It is very likely that the demonstration for radar would come first and very soon. To go into the visual will take some time but it is also not so far off," Leonhardt said.




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I've read about a system they came up with when they were working on stealth, I think they may have it active, but I have no evidence.

The way Radar works is that it transmits a pulse of energy and then looks to see that energy reflected back.

Someone thought of putting small antennas on the skin of an aircraft, when a energy pulse hit the skin the antenna reported the frequency and strength of the energy pulse and the computer then generated a 'null pulse' at the same frequency, which canceled out the radar signal reflected back to the transmitting site, effectively making the aircraft invisible to radar.

Then someone suggested generating a null pulse at the visible light frequency range, light hits the skin of the aircraft, but it's not reflected back to the human eye.

I understand it's not perfect, you look and don't see the aircraft, but if you concentrate you can see a distortion.

Read the actual paper: U. Leonhardt, Optical Conformal Mapping, Science 312, 1777-1780 (2006), published online 25 May 2006 [DOI: 10.1126/science.1126493] (in Science Express Reports)