Tuesday, August 01, 2006: H. G. Wells tried to do it in The Invisible Man, Hollywood played with the idea in Hollow Man and Bollywood in Mr India. Now, it is the turn of the new-age wizard, Dr Ulf Leonhardt, a theoretical physicist at St Andrews University in Scotland, who believes, "Objects are visible because they reflect light rays. To be invisible, an object would have to let light pass through it, like H. G. Well's Invisible Man."
The bending of light is the cause of many optical illusions, such as mirages in the desert. Light bends in the hotter air near the ground in the desert and this causes a reflection of the sky on the ground – a mirage.

Dr Leonhardt said, "The devices work by bending light, as in a mirage. However, a mirage involves the reflection of light which produces the shiny image that can be seen. An invisibility device bends light without producing an image. To do this, the devices must have carefully designed refractive index profiles."

Developing such devices still remains in the realm of future, but according to Dr Leonhardt, scientists are making advances in metamaterials -- artificial materials with unusual properties that could be used to make invisibility devices.

In his paper, Dr Ulf Leonhardt writes, "Strictly speaking, ideal invisibility devices based on isotropic media are impossible due to the wave nature of light. Highly anisotropic media, however, may lead, in principle, to the construction of perfect invisibility devices.'

This paper considers invisibility devices based on optical conformal mapping. The paper shows that the time delays do not depend on the directions and impact parameters of incident light rays, although the refractive-index profile of any conformal invisibility device is necessarily asymmetric. The distortions of images are thus uniform, which reduces the risk of detection. The paper also shows how the ideas of invisibility devices are connected to the transmutation of force, the stereographic projection and Escheresque tilings of the plane.

It seems, it will not be long enough when invisible men will be roaming around us. Will then we be requiring invisible laws?

Read full paper : Notes on conformal invisibility devices