Invisibility ring.Scientists can't yet make an invisibility cloak like the one that Harry Potter uses. But, for the first time, they've constructed a simple cloaking device Not to be confused with Cloak of invisibility. In several science fiction universes, a cloaking device is an advanced stealth system which causes an object, such as a spaceship or individual, to be invisible and extremely difficult to detect with normal sensors. that makes itself and something placed inside it invisible to microwaves. When a person "sees" an object, his or her eye senses many different waves of visible light as they bounce off the object. The eye and brain then work together to organize these sensations and reconstruct the object's original shape. So, to make an object invisible, scientists have to keep waves from bouncing off it. And they have to make sure the object casts no shadow. Otherwise, the absence of reflected light on one side would give the object away. Invisibility isn't possible yet with waves of light that the human eye can see. But it is now possible with microwaves. Like visible light, microwaves are a form of radiant energy radiant energy n. Energy transferred by radiation, especially by an electromagnetic wave. radiant energy Noun . They are part of the electromagnetic spectrum electromagnetic spectrum Total range of frequencies or wavelengths of electromagnetic radiation. The spectrum ranges from waves of long wavelength (low frequency) to those of short wavelength (high frequency); it comprises, in order of increasing frequency (or decreasing , which also includes radio waves Radio waves Electromagnetic energy of the frequency range corresponding to that used in radio communications, usually 10,000 cycles per second to 300 billion cycles per second. , infrared light, ultraviolet rays Ultraviolet rays Invisible light rays with a wavelength shorter than that of visible light but longer than that of x rays. Mentioned in: Sunscreens , X rays, and gamma rays Gamma rays Electromagnetic radiation emitted from excited atomic nuclei as an integral part of the process whereby the nucleus rearranges itself into a state of lower excitation (that is, energy content). . The wavelengths of microwaves are shorter than those of radio waves but longer than those of visible light. The scientists' new "invisibility device" is the size of a drink coaster and shaped like a ring. The ring is made of a special material with unusual abilities. When microwaves strike the ring, very few bounce off it. Instead, they pass through the ring, which bends the waves all the way around until they reach the opposite side. The waves then return to their original paths. To a detector set up to receive microwaves on the other side of the ring, it looks as if the waves never changed their paths--as if there were no object in the way! So, the ring is effectively invisible. When the researchers put a small copper loop inside the ring, it, too, is nearly invisible. However, the cloaking device and anything inside it do cast a pale shadow. And the device works only for microwaves, not for visible light or any other kind of electromagnetic radiation electromagnetic radiation, energy radiated in the form of a wave as a result of the motion of electric charges. A moving charge gives rise to a magnetic field, and if the motion is changing (accelerated), then the magnetic field varies and in turn produces an . So, Harry Potter's invisibility cloak doesn't have any real competition yet. http://www.sciencenewsforkids.org/articles/20061025/Note3.asp From Science News for Kids Oct. 25, 2006. Copyright (c) 2006 Science Service. All rights reserved. |
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