Ever since H G Wells wrote his masterpiece The Invisible Man in 1897, the concept of roaming about unseen has fascinated mankind. The advantages of being indiscernible have ranged in popular imagination from spying on others and, as in the James Bond movie Die Another Day using an undetectable car to hunt down an enemy. Magicians, of course, have long used the trick to astonish audiences. Now, the hidden wish of those who want to disappear has come true. Scientists are in the process of inventing a technology, which uses meta-materials, or man-made materials, to allow electromagnetic waves to go around objects and come out on the other side as if there is nothing in between. The idea of an invisibility cloak germinated in 2006 when John Pendry of Imperial College, London, and David Schurig and David Smith of Duke University, presented the theory of ‘transformation optics’ in Science. The theory was demonstrated for the first time with microwaves a year later.
Since then, there has been a flurry of activity with experiments in different wavelengths, including those in which we see. Although total invisibility is yet to be achieved, steps towards this end are being taken by David Smith and his Duke University colleague, Nathan Landy, who are trying to ensure that light passes around a microwave ‘cloak’ with no reflections.
It is too early to speculate on how the world will change once this ‘cloak’ becomes available. Apart from the appearance of films with weird plots, espionage will not be the same again. Nor will husbands and wives feel secure in the knowledge that their spouses are not breathing down their necks. Educational authorities will also be in a quandary about preparing question papers that will not be leaked by an invisible student. As in Wells’ classic, scientists and laymen will probably soon discover that becoming invisible is not an unmixed blessing.