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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.

詞匯：

cloak n.斗篷，披風 hyperlens n.超透鏡

metamaterial n.超材料 acoustics n.聲學

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

注釋：

1.Invisibility cloaks：隱形衣。在《哈利·波特與死亡圣器》(Harry Potter and the Deathly Hallows)一書中，哈利通過鄧布利多的轉交繼承了他父親的隱形衣。該書是英國女作家J.K.羅琳創作的哈利·波特系列小說的第7部。

2.…had it not been for the development of metamaterials：……如果超材料尚未得到開發的話。該句使用的是虛擬過去時的倒裝結構。虛擬過去時表示與過去事實相反的假設;因為是倒裝結構，所以將情態動詞had提到主語之前。如使用正常語序，該句可寫為....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"的詞義是“超越”，metamaterials(超材料)能做出我們在自然界看不到的事情，例如將光波移動到某個物體周圍，然后將光波全部收回。

4.Louisiana Tech University in Ruston，Louisiana：路易斯安那理工大學，位于路易斯安那州拉斯頓市。該校為公立大學，1894年建校，是美國最為重要的研究型大學之一。

5.the Polytechnic University of Valencia in Spain：瓦倫西亞理工大學，位于西班牙東南部的瓦倫西亞市，該校建于1968年。

6.oil rigs：石油鉆塔