By Andrew Grant
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Making something invisible does not require complex materials and techniques. Well-placed mirrors or lenses can cloak fish, cats and even people, two new studies show.
Since 2006, physicists have engineered intricate materials that can steer light waves around an object to render it invisible. But such cloaks can manipulate only a narrow range of wavelengths, a far cry from the full spectrum seen by people.
John Howell, a physicist at the University of Rochester in New York, realized that plenty of simple, off-the-shelf materials can also steer light. During Thanksgiving break last year, Howell and his 14-year-old son Benjamin designed three devices that hide life-size objects from sight. One uses L-shaped water tanks, another a network of lenses and the third a set of mirrors; all of them function on the principles of reflection and refraction that students learn in high school physics. The Howells reported June 10 at arXiv.org that they cloaked chairs, toy helicopters and people, though the cloaks worked only when viewed from one direction.