阅读第四十六篇：不可思议的超材料

　　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 think of an idea for a new behavior for light, then the engineers can find a way to design a device using rnetamaterials. "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 respdnd to metamaterials。

　　At the Polytechnic University of Valencia in Spain5, José Sánchez-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。

　　Sánchez-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。

　　练习：

　　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 Sánchez-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。

　　译文：

　　如果尚未开发超材料的话，隐形衣可能永远不可能，只能在科幻小说中看到。在希腊语中，“meta”的意思是“超越”，超材料能完成我们在自然界无法看到的事，例如将转移某物体周围的光波，然后将光波全部收回。如果科学家能够做出完全成熟的隐身衣，那很可能是有超材料制成的。

　　工程师Dentcho Genov说，“我们创造的是大自然不存在的材料，这些材料的物理现象在自然中也不存在。这最令人激动。” Genov在位于拉斯顿市的路易斯安那理工大学设计和制作超材料，例如能运用到隐身衣中的超材料。

　　隐身衣可能不是超材料领域的第一个重要成果，其他应用也同样令人振奋。例如，很多实验室的科学家正致力于建造超透镜。透镜通常由玻璃制成，能够改变光波的方向。显微镜和照相机中的透镜能够聚光，因此研究人员能够看到微小的物体，摄影师能够捕捉远处的影像。

　　而超透镜是由超材料构成。由于超材料能够完成普通材料无法做到的事情，超透镜会成为强大的工具。研究人员能够利用超透镜看到想象当中最微小的事物——例如和可见光的波长一样小的事物。

　　Genov指出，超材料科学是由想象力推动的：如果能够想到光的新行为，工程师就有办法来设计使用超材料的设备。他说，“我们需要想象力丰富的人。”

　　从2006年起，许多实验室开始探索不仅仅利用可见光的其他超材料。事实上，科学家发现几乎所有种类的波都对超材料有反应。

　　西班牙瓦伦西亚理工大学的Jose Sanchez-Dehesa在研究声学。和隐形衣移动光波的原理类似，“隐声衣”会以自然界不存在的方式来移动声波。例如，“隐声衣”会改变音乐厅内声波的方向——这样，坐在柱子后面的人和其他观众收听音乐会的效果一样，不会受到任何干扰。

　　最近，工程师Sanchez-Dehesa表示有可能制成“隐声衣”，但他怀疑能否很快实现。他说，“这在理论上是可能的。”但他补充说，实际上可能无法制成。

　　其他科学家正在研究用更大的超材料为岛屿和石油钻塔进行防护的方法，以使它们免受海啸的侵害。海啸是强大的破坏性波浪，超材料可以让钻塔和岛屿周围的海啸改变方向，波浪会沿着相反方向继续前进，不会造成任何破坏。

　　答案：

　　理工类

　　第二篇

　　1.B  2.D  3.D  4.A  5.B

　　第六篇

　　1.B  2.D  3.C  4.A  5.C

　　第三十四篇

　　1.C  2.C  3.D  4.D  5.A

　　第三十八篇

　　1.D  2.B  3.C  4.D  5.A

　　第四十五篇

　　1.C  2.A  3.B  4.C  5.A

　　第四十六篇

　　1.C  2.D  3.C  4.B  5.A

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