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 ____1____. Their work appears in the journal Nature Photonics.
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 ____2____, they give that object momentum. That’s why comet tails always ____3____ 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 ____4____ 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 “____5____”.
give you a lift reflect off of something point away from plopped traveling light
(give a lift 搭便车) 物理学家利用光使微小的翼状物飞起 一说到飞翔,你必定会想到空气。风拂过你的脸颊,吹过你的后背,托起你的双翼。现在,物理学家们注意到,光也可以搭你一程。他们的研究成果发表在《自然光子学》杂志上。 悬浮空中取决于对压力的利用。以飞机为例,它双翼上方与下方的压力各不相同,正是这不同的压力使得飞行器保持悬浮。但是空气并非产生压力的唯一途径。光也做得到。当光子穿过某物或由某物反射时,就会给该物体一个动量。这就是为什么彗尾总是背离太阳的方向。太阳辐射和太阳风使其如此。 因此,物理学家开始忖度能否利用辐射压力使物体高飞。他们设计的飞行器是一个细菌大小的翼状杆。他们让这个翼状杆落入盛有水的烧杯中,并用激光束从底部击中它。研究结果表明,该翼状杆会向上运动,移到一旁——这标志着是光造成的上升运动。这一发现可以为星际旅居设计太阳风帆。或许,还会为短语“轻装旅行(traveling light)”赋予新的意义。