July 17, 2009 -- A universal mirror, an object that reflects all light waves back at their source, has been created by scientists in Europe and Asia. Imagine a tennis player hitting a ball against a wall. The ball would bounce right back to the player no matter what angle he or she directed the shot. A universal mirror has the same effect, except with light waves. Unlike an ordinary mirror, which only reflects objects at 90 degrees, a universal mirror reflects objects back at any angle. In other words, a person positioned in front of a large, optical universal mirror would see his or her own reflection perfectly no matter where the person stands. "(A universal mirror) makes things become very visible," said Ulf Leonhardt, a professor at the University of St. Andrews and co-author of a paper in the current issue of Nature Materials. "It's the exact opposite of an invisibility cloak." Unlike a universal mirror, an invisibility cloak guides light waves around an object in order to conceal it. Although universal mirrors and invisibility cloaks might preform opposite functions, they each employ the same technology: metamaterials. Related Content:
While the properties of normal materials are predominantly determined by their chemical composition, metamaterials are artificial materials that derive their properties from their physical structures. Universal mirrors and invisibility cloaks both manipulate light waves by using tiny structures much smaller than the wavelength of light itself. This capability is engineered using the metamaterials from which universal mirrors and invisibility cloaks are created. Creating structures as small as metamaterials is a difficult task, which is why both invisibility cloaks and universal mirrors can only handle relatively long microwaves. Structures that perfectly manipulate shorter wavelengths of light -- wavelengths the human eye can actually see -- have yet to be produced. The universal mirror, or omnidirectional retroreflector as it's called in the Nature Materials paper, is about one centimeter high (0.4 inches), 10 centimeters (four inches) in diameter, and made of copper circuit boards covered in circles three millimeters (0.1 inches) across. When microwaves three centimeters (1.2 inches) long hit the small circles, they are forced backward at the same angle from which they came. When microwaves hit most other materials, they bounce forward at the same angle. Get More NewsSpiders, Scorpions Among World's Oldest CreaturesMany creepy crawlies have been on Earth much longer than previously believed.Blood-Sucking Vampire Bats Sing DuetsWhite-winged vampire bats "harmonize" with separated roost mates.Oldest Hebrew Writing Possibly FoundAncient inscriptions on a 3,000-year-old pottery shard could make history.Rare, Prehistoric-Age Reptile Found in N.Z.A tuatara has been spotted on the New Zealand mainland for the first time in 200 years.Iceman Has No Living RelativesOetzi, the 5,300 year-old frozen mummy, left no living genetic legacy.SLIDE SHOW: Landscapes of TerrorWhat makes a place feel scary? There are scientific explanations.It's Official: People Are Warming the PolesHumans are conclusively to blame for polar warming, say scientists.Eight-Armed Animal Preceded DinosaursWhat may be one of Earth's first animals was no bigger than a coaster and had eight arms.Phoenicians Live on in People's GenesOne in 17 Mediterranean men may be descended from ancient Phoenicians.Pesticides, Fertilizers Linked to Frog DeclineA pesticide is found to promote parasites among amphibians.Hubble Telescope Taking Photos AgainThe Hubble Space Telescope is once again snapping stunning photos of the universe.Andean Mummy Hairs Show Hallucinogen UseScientists find direct evidence of hallucinogenic drug use among ancient Andeans.Opals on Mars Reveal Planet's Long Wet PastOpals found on Mars suggest the planet has been wet for much longer. |
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