Ever since H.G. Wells wrote his masterpiece, The Invisible Man, the concept has fascinated scientists and laymen — and not always for the loftiest of motives. One objective has been to be a voyeur, or the so-called fly on the wall, who can see what his friends and foes are up to. Not surprisingly, this capacity to be undetectable has been of considerable interest to all warriors. Julius Caesar is known to have covered his ships in blue-green wax, including the sails, ropes and even the crew, making the vessels virtually invisible against the sea. Some animals have perfected the art effectively enough to deceive the predators. Beyond fiction and animal life, however, the scientists are now trying to ascertain how imperceptibility can become a part of the real world.
The latest in this field is the group of Baile Zhang, an assistant professor of physics at Nanyang technological university in Singapore, who recently displayed his “invisibility cloak” at Long Beach, California. Zhang’s device is in its early stages, just a small gizmo in prototype phase, but it works. A small box made of calcite optical crystal was used to bend rays of light around an object, making anything placed behind the box invisible.
It is now known that American scientists have also been working on their own versions of the invisibility cloak, using novel materials to manipulate light. The value of such experiments to the military and spy agencies is obvious. The day, therefore, may not be far off when concealments of this nature will become commonplace, reversing the millennia-old technique of the animal world by enabling the predators to approach their victims unseen. The danger to countries which do not have the resources to develop such gadgets is obvious. It may be well to remember, however, that the scientist who made himself invisible in Wells’ story did not meet with a happy end.