A Star Trek-style "cloaking device" has been built using technology developed to make objects invisible.
The "cloak", based on a British design concept, measures less than five inches across and only responds to radar waves. But within five years there might be devices powerful enough to make whole vehicles "vanish" - including battlefield tanks.
An invisibility cloak blueprint was produced in May by Professor Sir John Pendry, a physicist at Imperial College London. Scientists working with him in the US have put the idea into practice. The concept involves bending visible light, or other forms of electromagnetic radiation such as radar, around the object being hidden. An observer looking at the object will see light deflected from behind, making it seem to disappear.
Scientists cannot yet steer visible light in this way. But the researchers at Duke University in Durham, North Carolina, have built a prototype device that is invisible to radar.
Sir John said yesterday: "The previous paper was all theory, explaining how it could be done, but the real challenge was to make the unusual materials needed for a working device ... I would have thought that in five years you'd be seeing some sort of practical realisation of this technology."