IT BEGAN as just a wizard idea from a British scientist. Yesterday it became a reality.

And reality began to disappear.

Following in the footsteps of Harry Potter, it was revealed that the world’s first invisibility cloak has been tested in America. So far the device is rather limited — it is 5in (13cm) wide and can hide an object only from microwave beams.

But the principle established by Sir John Pendry, a professor at Imperial College, London, has been proved to work and in the next five years there are hopes that total invisibility may become possible for larger objects. Tanks, for example.

Laboratory experiments at Duke University, North Carolina, were funded by the US intelligence community. Using copper rings and metamaterials — artifical composites — arranged in concentric circles, it was shown that microwave radiation can be deflected past an object just as water will flow past an obstacle.

When a beam was aimed at the device, sensors were unable to “see” the object hidden in the middle because the microwaves were not bounced back.

“Our cloak allows a concealed volume, plus the cloak, to appear to have properties similar to free space when viewed externally,” Professor David Smith, of Duke University, said. “The cloak deflects microwave beams so they flow around a ‘hidden’ object, making it appear almost as if nothing were there at all. The waves’ movement is similar to river water flowing around a smooth rock.”

The cloaking device, reported in Science Express, the online version of the journal Science, was designed by David Schurig, of Duke University, who said that it had the effect of warping space. “You cannot easily warp space but you can achieve the same effect on electromagnetic fields using materials with the right response,” he said. “The required materials are quite complex.”

He compared the deflection of the microwaves to pushing a knitting needle into fabric. The threads are pushed aside but do not break.

The US team produced the cloak according to electromagnetic specifications determined by a design theory proposed by Sir John, 63. The artificial composites in metamaterials react with electromagnetic waves in a way that natural materials would not.

Sir John said: “The real challenge was to make the unusual materials needed for a working device. It’s all been done in a timescale much shorter than I had envisaged. This cloaking device is just a demonstration showing that you can get radiation where you want it to be.

“There’s still some development to do, but I would have thought that in five years you’d be seeing some sort of practical realisation of this technology. It’s probably too heavy for aircraft, and making objects as big as buildings disappear might be difficult. But it would be ideal for hiding a tank.”

The technology also has non-military applications, such as protecting sensitive electronic equipment from radio interference. Sir John’s work was funded by the Engineering and Physical Sciences Research Council. Researchers are uncertain how long it will take, or even if it is possible, to work out how to build a device to warp lightwaves but said that their findings represented a “baby step on the road to actual applications for invisibility”. Before scientists could make an object vanish before a person’s eyes, a cloak would have to be devised that simultaneously interacted with all the wavelengths in light.

The report added: “The agreement shown here between simulation and experiment is evidence that metamaterials can indeed be designed to exacting specifications. Though the invisibility is imperfect due to the approximations used and material absorbtion, our results provide an experimental display of the electromagnetic cloaking mechanism.”

Other scientists in the field were impressed by the results, coming just five months after it was announced that cloaking is theoretically possible. Ulf Leonard, of the University of St Andrews, told Science: “It’s a very good achievement. It’s surprising that it’s as simple as it is and that it works so well.”

NOW YOU SEE IT ...

Hollow Man: film released in 2000 stars Kevin Bacon as a scientist who takes an invisibility serum and goes mad