Invisible: Beyond the invisibility cloak

 作者:归缀於     |      日期:2019-03-01 05:08:01
By Jeff Hecht Merely going unseen won’t silence your footsteps or neutralise your body heat. Now researchers are working on true stealth The most cunning paint job may be no use as camouflage. It won’t do much to hide you from the prying eye of a thermal camera, or silence an inadvertent sneeze. Even something as subtle as a shadow can give your presence away. To win in the ultimate game of hide-and-seek, what you need is an invisibility cloak that goes way beyond simply not being visible. That might seem a tall order, yet researchers are racing to perfect the technology. So could their devices make you disappear completely? This is where the future of concealment begins to look hazy. An invisible man needs to be more than just unseen (Image: Paul Reed/Associated Newspapers/Rex) First, consider what it would take to make you vanish. If you could wear something that bends light rays from the wall behind you smoothly around your body – like water flowing around a rock – then steer them towards someone looking in your direction, they would see nothing but the wall: no outline, no shadow. This trick is not too difficult to accomplish. Last year a team led by Hongsheng Chen from Zhejiang University in Hangzhou, China, used special optics to diffract light around a cat, making it vanish from view. Unfortunately, the effect only works at certain viewing angles. And the system isn’t portable – it uses a large and very heavy glass prism. Less cloak, more bunker. Video: