Thanks to heated sheets of carbon nanotubes, underwater invisibility cloaks on a large scale could be closer to reality than you think. In technical terms, “Ali Aliev and colleagues at the University of Texas in Dallas embedded a sheet of carbon nanotubes into aerogel, a foam-like material; when electrically heated, the nanotubes bent light waves to create a mirage, effectively cloaking the sheet and anything behind it.” Video after the break.
Aliev says the mirage forms because the nanotubes transfer heat to the surrounding air more efficiently than regular metals, allowing a steeper temperature gradient to form near the device’s surface. Because photothermal deflection depends on light’s ability to propagate faster through hotter, less-dense material, the device works better when the temperature gradient is steeper. Plus, he adds, because carbon nanotubes do not store heat well, the mirage can be turned on and off quickly.