June 15, 2009 -- A new invisibility cloak for sound could help doctors find tiny tumors or hide submarines from enemy sonar. "Our focus is not about dampening noise, but to guide sound waves around structures," said Nicholas Fang, a professor a the University of Illinois at Urbana Champaign and coauthor, along with Shu Zhang and Leilei Yin, on a paper that appears in the journal Physical Review Letters. Watch video: Scientists work on invisibility tech for soldiers of the future. For example, "if we have a coating on a submarine that bends acoustics waves before they hit the surface, guiding them around the submarine smoothly, then you won't be able to detect a submarine using sonar." The same technology that could render a military submarine invisible to sonar could also be used to create high-definition, in-utero baby pictures or detect previously undetectable, tiny tumors. Invisibility cloaks, whether for sound or light, both manipulate waves. Harry Potter-style invisibility cloaks manipulate beams of light. Acoustic invisibility cloaks manipulate waves of pressure. Whatever the wave type, the principle is basically the same; bend a wave around an object without breaking it. Related Content:
The concept is the same, but the design is quite different. One of the many differences between the two types of waves is size. Sound waves are larger than electromagnetic waves. To manipulate either wave requires structures many times smaller than the size of the wave. Because the properties of the material are determined by their physical structure and not their chemical make-up, as they traditionally are, they are called metamaterials. "If you need to build an ultrasonic metamaterial, the dimension of the physical structure is tens or hundreds of microns," said Fang. "Compare that with optical metamaterials, and you are talking about hundreds of nanometers. That makes it a lot more amenable for research." The sonic invisibility cloak works a lot like a musical instrument. Musical instruments amplify sound waves using shaped cavities. The sonic metamaterial uses cubes and octagons to create holes that can then bend the wave around the structure. The most obvious application would be as a coating for submarines that want to avoid detection from enemy sonar. 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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