Scientists have created a working cloaking device that can be switched off and on and which hides an object by creating a mirage.
The cloak, from researchers at the University of Dallas, is based on sheets of carbon nanotubes. And, of their many weird and wonderful properties, it's their exceptional ability to conduct heat and transfer it to surrounding areas that's behind the new cloaking effect.
The mirage effect, frequently observed in deserts or on long roads in the summer, is an optical phenomenon in which light rays are bent by heat to produce a displaced image of distant objects or the sky.
Through electrical stimulation, the transparent sheet of highly aligned carbon nanotubes can be easily heated to high temperatures.
The nanotubes can then transfer that heat to the surrounding area, causing a steep temperature gradient. This causes the light rays to bend away from the object concealed behind the device, making it appear invisible. The device works best underwater.
"Using these nanotube sheets, concealment can be realized over the entire optical range and rapidly turned on and off at will, using either electrical heating or a pulse of electromagnetic radiation," says lead author Dr Ali Aliev.
"The research results also provide useful insights into the optimization of nanotube sheets as thermoacoustic projectors for loudspeaker and sonar applications, where sound is produced by heating using an alternating electrical current."