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Marvelous Metamaterials

Invisibility cloaks1 would have remained impossible，forever locked in science fiction，had it not been for the development of metamaterials2.In Greek，“meta”means beyond，and metamaterials can do things beyond what we see in the natural world-like shuffle light waves around an object，and then bring them back together3.If scientists ever manage to build a full-fledged invisibility cloak，it will probably be made of metamaterials.

“We are creating materials that don’t exist in nature，and that have a physical phenomenon that doesn't exist in nature，”says engineer Dentcho Genov.“That is the most exciting thing.”Genov designs and builds metamaterials-such as those used in cloaking-at Louisiana Tech University in Ruston，Louisiana4.

An invisibility cloak will probably not be the first major accomplishment to come from the field of metamaterials.Other applications are just as exciting.In many labs，for example，scientists are working on building a hyperlens.A lens is a device-usually made of glass-that can change the direction of light waves.Lenses are used in microscopes and cameras to focus light，thus allowing a researcher to see small things or a photographer to capture image of things that are far away.

A hyperlens，however，would be made of metamaterials.And since metamaterials can do things with light that ordinary materials can”t，the hyperlens would be a powerful tool.A hyperlens would allow researchers to see things at the smallest scale imaginable-as small as the wavelength of visible light.

Genov points out that the science of metamaterials is driven by the imagination：If someone can mink of an idea for a new behavior for light，then the engineers can find a way to design a device using metamaterials.“We need people who can imagine，”he says.

Since 2006，many laboratories have been exploring other kinds of metamaterials that don”t involve just visible light.In fact，scientists are finding that almost any kind of wave may respond to metamaterials.

At the Polytechnic University of Valencia in Spain5，Jose Sanchez-Dehesa is working with acoustics, or the science of sound.Just as an invisibility cloak shuffles waves of light，an“acoustic”cloak would shuffle waves of sound in a way that’s not found in nature.In an orchestra hall，for example.an acoustic cloak could redirect the sound waves-so someone sitting behind a column would hear the same concert as the rest of the audience，without distortion.

Sanchez-Dehesa，an engineer，recently showed that it’s possible to build such an acoustic cloak, though he doubts we’ll see one any time soon.“In principle，it is possible，”he says，but it might be impossible to make one，he adds.

Other scientists are looking into ways to use larger metamaterials as shields around islands or oil rigs6 as protection from tsunamis.A tsunami is a giant, destructive wave.The metamaterial would redirect the tsunami around the rig or island，and the wave would resume its journey on the other side without causing any harm.

词汇：

cloak n.斗篷，披风 hyperlens n.超透镜

metamaterial n.超材料 acoustics n.声学

full-fledged adj.完全成熟的，完全合格的tsunami n.海震，海啸

注释：

1.Invisibility cloaks：隐形衣。在《哈利·波特与死亡圣器》(Harry Potter and the Deathly Hallows)一书中，哈利通过邓布利多的转交继承了他父亲的隐形衣。该书是英国女作家J.K.罗琳创作的哈利·波特系列小说的第7部。

2.…had it not been for the development of metamaterials：……如果超材料尚未得到开发的话。该句使用的是虚拟过去时的倒装结构。虚拟过去时表示与过去事实相反的假设;因为是倒装结构，所以将情态动词had提到主语之前。如使用正常语序，该句可写为....if it had not been for the development of metamaterials.

3.“meta”means beyond, and metamaterials can do things beyond what we see in the natural world-like shuffle light waves around an object，and then bring them back together：“meta"的词义是“超越”，metamaterials(超材料)能做出我们在自然界看不到的事情，例如将光波移动到某个物体周围，然后将光波全部收回。

4.Louisiana Tech University in Ruston，Louisiana：路易斯安那理工大学，位于路易斯安那州拉斯顿市。该校为公立大学，1894年建校，是美国最为重要的研究型大学之一。

5.the Polytechnic University of Valencia in Spain：瓦伦西亚理工大学，位于西班牙东南部的瓦伦西亚市，该校建于1968年。

6.oil rigs：石油钻塔