Scottish university’s vanishing act


by a Newsnet reporter

Researchers working at the University of St Andews have devised a revolutionary new technique which allows the development of new camouflaging devices.  The research was published earlier this week in the science journal the New Journal of Physics.  The full text of the research article can be downloaded here.

Long a staple of science fiction, the ‘invisibility cloak’ is now a step closer to realisation.  Essentially the device works by creating an optical illusion.  The usual approach to designing an invisibility cloak works on the basis of bending light ― using highly specific materials ― around an object that you wish to conceal.  This prevents the light from hitting the object and revealing its presence so it appears invisible to the eye.  When light is bent it engulfs the object, much like water covering a rock sitting in a river bed, and carries on its path making it seem as if nothing is there.

However light can only be accelerated to a speed faster than it would travel in space under certain conditions, and this restricts invisibility cloaks to work in a limited part of the spectrum ― essentially just one colour.

This would be ideal if somebody was planning to stand still in camouflage but the moment that they start to move the scenery would begin to distort, revealing the person under the cloak.

Under the guidance of Professor Ulf Leonhardt, undergraduate student Janos Perczel, originating from Hungary and reading Logic, Philosophy of Science and Physics at the University of St Andrews, acknowledged the huge potential of the invisible sphere and was able to fine-tune it so that it was a suitable background for cloaking.

By slowing all of the light down with an invisible sphere, the St Andrews team discovered that it does not need to be accelerated to such high speeds and can therefore work in all parts of the spectrum.  

Perczel said, “Once the idea was present, I worked for over eight months to overcome the technical barriers and to make the proposal practicable.”

An Institute of Physics spokesperson said, “This new development opens up further possibilities for the design of a practical invisibility cloak ― overcoming the problem of light speed that other advances have struggled to address and, very impressively, this significant advance was achieved by an undergraduate student.”