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SSS 2010-12-07

时间:2011-01-06 06:20来源:互联网 提供网友:tianshun   字体: [ ]
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    (单词翻译:双击或拖选)

This is Scientific American’s 60-Second Science. I’m Karen Hopkin. This will just take a minute.


Think about flying and you no doubt think about air--the wind in your face, the wind at your back, the wind beneath your wings. Now physicists1 note that light can also give you a lift. Their work appears in the journal Nature Photonics.

 


Staying aloft is a matter of dealing2 with pressure. In the case of a plane, it’s the difference in pressure on the top and bottom of its wings that keeps the craft afloat. But air isn’t the only way to generate pressure. Light can do the same. When photons pass through or reflect off of something, they give that object momentum3. That’s why comet tails always point away from the sun. Solar radiation and wind push them that way.

 


So physicists got to wondering whether radiation pressure could be harnessed to help an item soar. The craft they deployed4 was a wing-shaped rod the size of a bacterium5. They plopped this rod into a beaker of water and hit it with a laser beam from below and found that the rod moved upward and to the side—a sign of optical lift. The finding could aid the design of solar sails for interstellar sojourns6 and perhaps give new meaning to the phrase “traveling light”.

 


Thanks for the minute. For Scientific American’s 60-Second Science, I’m Karen Hopkin.


点击收听单词发音收听单词发音  

1 physicists 18316b43c980524885c1a898ed1528b1     
物理学家( physicist的名词复数 )
参考例句:
  • For many particle physicists, however, it was a year of frustration. 对于许多粒子物理学家来说,这是受挫折的一年。 来自英汉非文学 - 科技
  • Physicists seek rules or patterns to provide a framework. 物理学家寻求用法则或图式来构成一个框架。
2 dealing NvjzWP     
n.经商方法,待人态度
参考例句:
  • This store has an excellent reputation for fair dealing.该商店因买卖公道而享有极高的声誉。
  • His fair dealing earned our confidence.他的诚实的行为获得我们的信任。
3 momentum DjZy8     
n.动力,冲力,势头;动量
参考例句:
  • We exploit the energy and momentum conservation laws in this way.我们就是这样利用能量和动量守恒定律的。
  • The law of momentum conservation could supplant Newton's third law.动量守恒定律可以取代牛顿第三定律。
4 deployed 4ceaf19fb3d0a70e329fcd3777bb05ea     
(尤指军事行动)使展开( deploy的过去式和过去分词 ); 施展; 部署; 有效地利用
参考例句:
  • Tanks have been deployed all along the front line. 沿整个前线已部署了坦克。
  • The artillery was deployed to bear on the fort. 火炮是对着那个碉堡部署的。
5 bacterium BN7zE     
n.(pl.)bacteria 细菌
参考例句:
  • The bacterium possibly goes in the human body by the mouth.细菌可能通过口进入人体。
  • A bacterium is identified as the cause for his duodenal ulcer.一种细菌被断定为造成他十二指肠溃疡的根源。
6 sojourns cdcad5f3c1bec37c5d4342afd91e9adf     
n.逗留,旅居( sojourn的名词复数 )
参考例句:
  • As an example, Edgar Cayce during a reading described his most recent sojourns throughout the cosmos. 例如,埃德加·凯西在一次解读中,描述了他最近的在宇宙中的逗留。 来自互联网
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