《那些古怪又讓人憂心的問題》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．如果一杯滿是水的杯子突然之間變成半空的杯子會怎麼樣？A. THE PESSIMIST IS PROBABLY more right about how it would turn out than the optimist.
A．相比起樂觀主義者，悲觀主義者大概更接近事實真相吧。
When people say “glass half empty,” they usually mean a glass containing equal parts water and air.
當人們說到“半空的杯子”時，他們通常指的是水和空氣各佔一半的體積。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.
傳統說法是，樂觀主義者看到的是半滿的杯子，而悲觀主義者看到的則是半空的杯子。這個故事衍生出了數不清的笑話，比如工程師看到的是所需大小兩倍的杯子，而超現實主義者看到的則是一隻在吃領帶的長頸鹿，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無一物——變成真空——又會怎麼樣呢？我知道這種真空不會持續很長時間，但之後會發生的事情取決於一個一般人不會在意的關鍵問題：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.
在這裏我們將討論3種不同的半空杯子的情形，然後在毫秒尺度上觀察那一瞬間之後會發生什麼。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.
中間的那個杯子裏是正常的一半水加上一半空氣，右邊那個杯子上面空的那一半變成了真空，而左邊那個杯子則是下面一半是真空。We'll imagine the vacuums appear at time t=0.
我們假設在t＝0時瞬間出現了真空。For the first handful of microseconds, nothing happens. On this timescale, even the air molecules are nearly stationary.
在起初的幾微秒內什麼事情都不會發生。在這一時間尺度下，甚至連空氣分子都幾乎是靜止的。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.
大部分時間，空氣分子以每秒幾百米的速度動來動去。但在任意給定的時刻，一些空氣分子會比其他空氣分子運動得更快。運動得最快的少數空氣分子的速度可能會突破每秒1千米，這些分子將是最先進入右邊杯子真空部分的空氣分子。
