《那些古怪又讓人憂心的問題》第112期:地球擴張(5)
t = 100 years
After 100 years, we'd be experiencing over 6 gees of gravity. Not only would we be unable to move around to find food, but our hearts would be unable to pump blood to our brains. Only small insects (and sea animals) would be physically able to move around. Perhaps humans could survive in specially built controlled-pressure domes, moving around by keeping most of our bodies submerged in water.
100年後，我們將感受到6倍重力。我們不僅沒法四處走動尋找食物，就連心臟都無力把血液泵到大腦中去。只有一些小昆蟲（和海洋生物）還有可能四處活動。也許人類可以在專門設計的控壓屋裏生存，要移動的話也要先把大部分身體浸在水裏。Breathing in this situation would be difficult. It's hard to suck in air against the weight of the water, which is why snorkels can only work when your lungs are near the surface.
在這種條件下呼吸是十分困難的。由於水的壓迫，你很難吸入空氣，這也是爲什麼呼吸管只在淺水裏纔有用。
Outside of low-pressure domes, the air would become unbreathable for a different reason. At somewhere around 6 atmospheres, even ordinary air becomes toxic. Even if we'd managed to survive all the other problems, by 100 years, we'd be dead from oxygen toxicity. Toxicity aside, breathing dense air is difficult simply because it's heavy.
出了控壓屋，你還是無法呼吸空氣，不過原因和之前的不一樣。在約6倍大氣壓下，即使是普通的空氣也變得有毒起來。即使我們能夠克服其他所有困難，100年後我們還是會死於空氣中毒。除去毒性不說，呼吸緻密的空氣也非常困難，因爲它太重了。Black hole?
黑洞？When would the Earth eventually become a black hole?
什麼時候地球會最終變成一個黑洞？It's hard to answer that, because the premise of the question is that the radius is steadily expanding while the density stays the same-whereas in a black hole, the density increases.
這個問題很難回答，因爲問題中說雖然半徑一直在變大，但密度一直不變——而在黑洞中，密度會增加。The dynamics of really huge rocky planets aren't often analyzed, since there's no obvious way that they could form; anything that large will have enough gravity to gather hydrogen and helium during planet formation and become a gas giant.
很少有人會去研究那些超大型的岩石行星的動力學，因爲它們很難形成：任何這麼大的東西在形成過程中都足以吸引大量的氫和氦，從而變成一顆氣態巨行星。At some point, our growing Earth would reach the point where adding more mass causes it to contract, rather than expand. After this point, it would collapse into something like a sputtering white dwarf or neutron star, and then-if its mass kept increasing-eventually become a black hole.
在未來的某一刻，不停擴張的地球總有一天會變成這樣的狀況：每增加一點質量，它都會縮小而不是變大。自那以後，它會不斷坍縮，直到變成一顆白矮星或者中子星——如果質量還是不停增加，它最終會變成一個黑洞。But before it gets that far . . .
但那要等好久……
