《那些古怪又讓人憂心的問題》第66期:人類大遷徙(3)
The first approach is the “space elevator” concept, a favorite of science fiction authors. The idea is that we connect a tether to a satellite orbiting far enough out that the tether is held taut by centrifugal force. Then we can send climbers up the rope using ordinary electricity and motors, powered by solar power, nuclear generators, or whatever works best. The biggest engineering hurdle is that the tether would have to be several times stronger than anything we can currently build. There are hopes that carbon nanotube-based materials could provide the required strength-adding this to the long list of engineering problems that can be waved away by tacking on the prefix “nano-.”
The second approach is nuclear pulse propulsion, a surprisingly plausible method for getting huge amounts of material moving really fast. The basic idea is that you toss a nuclear bomb behind you and ride the shockwave. You'd think the spacecraft would be vaporized, but it turns out that if it has a well-designed shield, the blast would fling away before it has a chance to disintegrate. If it could be made reliable enough, this system would in theory be capable of lifting entire city blocks into orbit, and could-potentially-accomplish our goal.
第二種方法就是核脈衝推進，這種方法能將極大質量的物體加速到很高的速度。它的基本原理就是你不停地往外扔核彈，然後藉助核爆的衝擊波前進。你可能覺得核爆會摧毀飛船，但事實是如果你能裝備一個精心設計的護盾，在護盾解體前衝擊波早就消散掉了。如果這套系統足夠可靠，那麼理論上它能把一整個街區送上太空，這樣離實現我們那個偉大目標也就不遠了。The engineering principles behind this were thought to be solid enough that in the 1960s, under the guidance of Freeman Dyson, the US government actually tried to build one of these spaceships. The story of that effort, dubbed Project Orion, is detailed in the excellent book of the same name by Freeman's son, George. Advocates for nuclear pulse propulsion are still disappointed that the project was cancelled before any prototypes were built. Others argue that when you think about what they were trying to do-put a gigantic nuclear arsenal in a box, hurl it high into the atmosphere, and bomb it repeatedly-it's terrifying that it got as far as it did.
這個方案背後的工程原理在20世紀60年代就已經被認定是非常健全的了，在弗里曼•戴森的指導下，美國政府曾一度想要造出這樣的飛船。這個項目被稱爲“獵戶座計劃”，弗里曼的兒子喬治寫的一本很棒的同名書裏詳細地介紹了這個項目。後來這個項目連一個原型機都沒造出來就被取消了，核脈衝推進的支持者們至今仍然對此耿耿於懷。但其他人則認爲當想象一下他們要做的事情——在一個盒子裏裝上大量核武器，把它拋到空中，然後不停地引爆核彈——這個項目居然還有目前的進展就已經讓人匪夷所思了。
So the answer is that while sending one person into space is easy, getting all of us there would tax our resources to the limit and possibly destroy the planet. It's a small step for a man, but a giant leap for mankind.
所以答案是隻把一個人送上太空是非常容易的事情，但要把所有人類都送入太空則會將我們的各種資源都推向極限，甚至還有可能毀掉整個地球。這時就真的是“一個人的一小步，全人類的一大步”了。1 There are probably around a million tons of pet dog in the US alone.
1． 單美國寵物狗的重量就有大約1億噸。Q. In Thor the main character is at one point spinning his hammer so fast that he creates a strong tornado. Would this be possible in real life?
Q．在電影《雷神》中，男主人公曾把他手中的錘子轉得飛快，以至於產生了強大的龍捲風。這在現實中是可能的嗎？Q. If you saved a whole life's worth of kissing and used all that suction power on one single kiss, how much suction force would that single kiss have?
Q．如果你把一輩子親吻的力氣都省下來，並且都用到一次親吻上，那麼你能產生多大的吸力？Q. How many nuclear missiles would have to be launched at the United States to turn it into a complete wasteland?
Q．需要多少射向美國的核導彈才能把美國徹底夷爲平地？
