《那些古怪又让人忧心的问题》第32期:小世界(3)
日期:2016-05-18 11:24

(单词翻译:单击)

Tidal forces would act on you in several ways. If you stretched your arm down toward the planet, it would be pulled much harder than the rest of you. And when you reach down with one arm, the rest of you gets pushed upward, which means other parts of your body feel even less gravity. Effectively, every part of your body would be trying to go in a different orbit. A large orbiting object under these kinds of tidal forces-say, a moon-will generally break apart into rings. This wouldn't happen to you. However, your orbit would become chaotic and unstable. These types of orbits were investigated in a paper by Radu D. Rugescu and Daniele Mortari. Their simulations showed that large, elongated objects follow strange paths around their central bodies. Even their centers of mass don't move in the traditional ellipses; some adopt pentagonal orbits, while others tumble chaotically and crash into the planet.
潮汐力会以不同的方式作用在你身上。如果你的双手下垂,那么手受到的引力就会比身体其他部分受到的引力大很多。如果你一只手往下伸,那么你身体的其他部分就会被向上推,也就是说,你身体的其他部分感受到的引力要更小一些。实际上你身体的不同部分都试图待在不同的轨道上。如果一个很大的物体——比如说月亮——处于这种潮汐力作用下,那么它一般会裂成碎片并形成一个光环。3但这事不会发生在你身上,只是你的轨道会变得很随机,并且很不稳定。拉杜•D.鲁杰斯库和达尼埃尔•莫尔塔里在一篇很有意思的论文里研究了这些轨道。他们的模拟结果显示,大型细长的物体会绕着中心星球以诡异的轨道运动,即使质心并不在传统的椭圆轨道上。在一些情况下,质心甚至会以五角星轨道运动,而另一些则像无头苍蝇一样乱转,最后一头栽倒在星球上。
This type of analysis could actually have practical applications. There have been various proposals over the years to use long, whirling tethers to move cargo in and out of gravity wells-a sort of free-floating space elevator. Such tethers could transport cargo to and from the surface of the Moon, or to pick up spacecraft from the edge of the Earth's atmosphere. The inherent instability of many tether orbits poses a challenge for such a project. As for the residents of our superdense asteroid, they'd have to be careful; if they ran too fast, they'd be in serious danger of entering orbit, going into a tumble and losing their lunch. Fortunately, vertical jumps would be fine. Cleveland-area fans of French children's literature were disappointed by the Prince's decision to sign with the Miami Heat.
这种分析并不是无聊为之,它其实可以用于实践。这几十年来一直有人提议使用极长的旋转绳索来将货物搬入或搬出重力阱——就像自由飘浮的太空电梯一样。这种绳索能够将货物运到月球表面或从那里运回,也可以在地球大气层边缘搭载航天飞机。只是这种绳索轨道内在的不稳定性给这些设想带来了巨大的挑战。但对于在这颗超级密实的星球上居住的人来说,他们可要小心一些:如果他们跑得太快,就很有可能飞进轨道,翻转成一团,并把午餐吐出来。不过你要是竖着跳就没什么问题。听说小王子和迈阿密热队签约了,克利夫兰的《小王子》迷们很不高兴。
1 Although not everyone sees it this way. Mallory Ortberg, writing on the-toast.net, characterized the story of The Little Prince as a wealthy child demanding that a plane crash survivor draw him pictures, then critiquing his drawing style.
1. 但并不是每个人都这么想。马洛里•奥特伯格曾在the-toast.net上撰文称《小王子》讲的是一个富有的小孩儿强制要求一位坠机幸存者给他画画,还批评他的画风。
2 . . . which is why it should really be called “escape speed” - the fact that it has no direction (which is the distinction between “speed” and “velocity”) is unexpectedly significant here.
2. ……这也是为什么它实际应该被称为“逃逸速率”——这里速率的无方向性(速度有方向性)莫名其妙地变得重要起来。
3 This is presumably what happened to Sonic the Hedgehog.
3. 这大概是刺猬索尼克的遭遇。

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