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____”.
【視聽版科學小組榮譽出品】
give you a lift reflect off of something point away from plopped traveling light
(give a lift 搭便車) 物理學家利用光使微小的翼狀物飛起 一說到飛翔，你必定會想到空氣。風拂過你的臉頰，吹過你的后背，托起你的雙翼?，F(xiàn)在，物理學家們注意到，光也可以搭你一程。他們的研究成果發(fā)表在《自然光子學》雜志上。 懸浮空中取決于對壓力的利用。以飛機為例，它雙翼上方與下方的壓力各不相同，正是這不同的壓力使得飛行器保持懸浮。但是空氣并非產(chǎn)生壓力的唯一途徑。光也做得到。當光子穿過某物或由某物反射時，就會給該物體一個動量。這就是為什么彗尾總是背離太陽的方向。太陽輻射和太陽風使其如此。 因此，物理學家開始忖度能否利用輻射壓力使物體高飛。他們設計的飛行器是一個細菌大小的翼狀桿。他們讓這個翼狀桿落入盛有水的燒杯中，并用激光束從底部擊中它。研究結果表明，該翼狀桿會向上運動，移到一旁——這標志著是光造成的上升運動。這一發(fā)現(xiàn)可以為星際旅居設計太陽風帆?；蛟S，還會為短語“輕裝旅行（traveling light）”賦予新的意義。