《那些古怪又让人忧心的问题》第42期:半空的杯子(1)
GLASS HALF EMPTY
Q. What if a glass of water was, all of a sudden, literally half empty?
Q．如果一杯满是水的杯子突然之间变成半空的杯子会怎么样？A. THE PESSIMIST IS PROBABLY more right about how it would turn out than the optimist.
A．相比起乐观主义者，悲观主义者大概更接近事实真相吧。
When people say “glass half empty,” they usually mean a glass containing equal parts water and air.
当人们说到“半空的杯子”时，他们通常指的是水和空气各占一半的体积。Traditionally, the optimist sees the glass as half full while the pessimist sees it as half empty. This has spawned a zillion joke variants-for example, the engineer sees a glass that's twice as big as it needs to be, the surrealist sees a giraffe eating a necktie, etc.
传统说法是，乐观主义者看到的是半满的杯子，而悲观主义者看到的则是半空的杯子。这个故事衍生出了数不清的笑话，比如工程师看到的是所需大小两倍的杯子，而超现实主义者看到的则是一只在吃领带的长颈鹿，等等。But what if the empty half of the glass were actually empty-a vacuum?The vacuum would definitely not last long. But exactly what happens depends on a key question that nobody usually bothers to ask: Which half is empty?
但如果杯子空的那一半真的是空无一物——变成真空——又会怎么样呢？我知道这种真空不会持续很长时间，但之后会发生的事情取决于一个一般人不会在意的关键问题：杯子的哪一半是空的？For our scenario, we'll imagine three different half-empty glasses, and follow what happens to them microsecond by microsecond.
在这里我们将讨论3种不同的半空杯子的情形，然后在毫秒尺度上观察那一瞬间之后会发生什么。In the middle is the traditional air/water glass. On the right is a glass like the traditional one, except the air is replaced by a vacuum. The glass on the left is half full of water and half empty-but it's the bottom half that's empty.
中间的那个杯子里是正常的一半水加上一半空气，右边那个杯子上面空的那一半变成了真空，而左边那个杯子则是下面一半是真空。We'll imagine the vacuums appear at time t=0.
我们假设在t＝0时瞬间出现了真空。For the first handful of microseconds, nothing happens. On this timescale, even the air molecules are nearly stationary.
在起初的几微秒内什么事情都不会发生。在这一时间尺度下，甚至连空气分子都几乎是静止的。For the most part, air molecules jiggle around at speeds of a few hundred meters per second. But at any given time, some happen to be moving faster than others. The fastest few are moving at over 1000 meters per second. These are the first to drift into the vacuum in the glass on the right.
大部分时间，空气分子以每秒几百米的速度动来动去。但在任意给定的时刻，一些空气分子会比其他空气分子运动得更快。运动得最快的少数空气分子的速度可能会突破每秒1千米，这些分子将是最先进入右边杯子真空部分的空气分子。
