Invisibility has been an ingredient of myths, novels and films for
millennia ? from Perseus versus Medusa in Greek legend to James
Bond?s latest car and Harry Potter?s cloak. A new study published
today by the Institute of Physics reveals that invisibility is
closer than we think. The paper, Notes on conformal invisibility
devices, published in the New Journal of Physics describes the
physics of several theoretical devices that could create the
ultimate illusion ? invisibility. ?Objects are visible because they
reflect light rays? says author Dr Ulf Leonhardt at St Andrews
University, Scotland. ?To be invisible, an object would have to let
light pass through it, like H. G. Well?s Invisible Man.
Alternatively light would have to bend around an object for it to
be invisible. The ideas in this paper are based around devices that
will bend light or radio waves around a hole inside the device. Any
object placed inside the hole will become invisible. The light
would flow round the hole like water around an obstacle.?
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 went on to say ?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. The paper explains the physics and
mathematics behind the devices using images rather than complex
equations: it visualizes invisibility.?