SSS 2010-12-07
时间：2019-01-08 作者：英语课 分类：Scientific American(十二)月
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 physicists 1 note that light can also give you a lift. Their work appears in the journal Nature Photonics.
Staying aloft is a matter of dealing 2 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 3. 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 4 was a wing-shaped rod the size of a bacterium 5. 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 6 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.
- 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。
- 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。
- 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。
- 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。
- 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。