第四十六篇
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(fēng) hyperlens n.超透鏡
metamaterial n.超材料 acoustics n.聲學(xué)
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(zhuǎn)交繼承了他父親的隱形衣。該書是英國女作家J.K.羅琳創(chuàng)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(fā)的話。該句使用的是虛擬過去時的倒裝結(jié)構(gòu)。虛擬過去時表示與過去事實相反的假設(shè);因為是倒裝結(jié) 構(gòu),所以將情態(tài)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(xué),位于路易斯安那州拉斯頓市。該校為公立大學(xué),1894年建校,是美國最為重要的研究型大學(xué)之一。
5.the Polytechnic University of Valencia in Spain:瓦倫西亞理工大學(xué),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
練習(xí):
1.What is true for metamaterials?
A.They will always remain in science fiction.
B.They are already a reality.
C.They are nonexistent in nature.
D.Scientists begin to use them to build invisible cloaks.
2.A hyperlens is a more powerful tool than a traditional lens
A.as it can allow scientists to see small things.
B.as it can help photographers to capture images far away.
C. even if it is made of ordinary materials.
D.as it can help scientists to see even the wavelengths of visible light.
3.Scientists at the Polytechnic University of Valencia try to invent
A.an acoustic cloak that can shuffle waves of light.
B.an invisible cloak that can shuffle waves of sound.
C.an acoustic cloak that can shuffle waves of sound.
D.a cloak that is made of materials found in nature.
4.According to Sanchez-Dehesa,
A.it is of great possibility to build an acoustic cloak soon.
B.it is possible to build an acoustic cloak in theory but far from reality.
C.it is totally impossible to build an acoustic cloak.
D.it is theoretically impractical to build an acoustic cloak.
5.What ways are some scientists looking into to protect the island and oil rig from tsunamis?
(Read the last paragraph.)
A.Surround them with metamaterials as protective shields.
B.Stopping the tsunami with metamaterials hours before it reaches them.
C.Building them with larger metamaterials to keep away tsunamis.
D.Using the equipment made of metamaterials to forecast arrival of a tsunami.
答案與題解:
1.C A不是正確答案,因為短文一開始的句子使用了虛擬語態(tài),句子的意思是:如果超
材料尚未得到開發(fā)的話……。也就是說,科學(xué)家已經(jīng)在研發(fā)超材料。短文的后面部分也進(jìn)一步提到科學(xué)家正致力于超材料的開發(fā)。但是因為超材料尚未研發(fā)成功,科學(xué)家更沒有開始使用超材料來制造隱身衣,所以B和D也不是正確選擇。第二段的第一句提供了答案。
2.D A、B所述功效均是第三段中普通的lens能夠達(dá)到的功效,所以不是正確選擇。Hyperlens不是用普通材料制成,所以C也是錯誤選擇。短文第四段對hyperlens做了描述,
結(jié)合第四段內(nèi)容可以得到D選項提供的結(jié)論。
3.C短文的第七段提供了答案。該段的大意是:瓦倫西亞理工大學(xué)的研究者Jose Sanchez-Dehesa試圖研發(fā)acoustic cloak,其原理與invisible cloak相同,只是acoustic cloak移動聲波(shuffle waves of sound),而不是移動光波(shuffle waves of light)。所以,只有C是正確的選擇。
4.B 短文的第八段提供了答案。工程師Sanchez-Dehesa認(rèn)為,成功開發(fā)acoustic cloak在理論上是可能的,但他對是否能成功表現(xiàn)出懷疑。
5.A 短文的最后一段告訴我們,科學(xué)家也在研究如何將超材料應(yīng)用于抵御海嘯的襲擊??梢栽趰u嶼周圍使用超材料作為防護(hù)(shields),因為超材料可以讓海嘯 改變行走方向(redirect tsunami)。A表達(dá)了這層意思,所以是答案。文章沒有說,在海嘯到達(dá)之前數(shù)小時用超材料
將海嘯檔住,B不是答案。文章沒有建議用超材料建造海島和石油鉆塔,C不是答案。D的內(nèi)容是用超材料制作海嘯預(yù)警器,文章中沒有提及,也不是答案
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