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托福听力练习-科学美国人60秒:用光托起小机翼

2017-06-05 12:18:00来源：科学美国人60秒

点击查看>>科学美国人60秒音频：用光托起小机翼

　　科学美国人60秒听力练习：用光托起小机翼

　　科学美国人60秒英文文本

　　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 physicists note that light can also give you a lift. Their work appears in the journal Nature Photonics. [Grover Swartzlander et al., "Stable Optical Lift"]

　　Staying aloft is a matter of dealing 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 momentum. 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 deployed was a wing-shaped rod the size of a bacterium. 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 sojourns. And perhaps give new meaning to the phrase “traveling light”.

　　—Karen Hopkin

　　中文翻译请点击下一页

本文关键字: 托福听力 科学美国人60秒

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