until you have to figure out where you put it
after you take it off...
Harry Potter isn't the only academic with an
invisibility cloak. A professor at the University of Tokyo has created an
optical camouflage system that makes anyone wearing a special reflective
material seem to disappear. Here's how: a video camera records the real-life
scenery behind the subject, transmits that image to a front-mounted projector,
which then displays the scene on the reflective material.