真正在量的那個距離
這是這個字的本業：天文學用來量星星之間有多遠的單位。名字裡有 year，量的卻是長度。
noun · B2
A unit used for measuring the very long distances between stars: the distance that light travels in one year, about 9.46 trillion kilometres.
光年
核心畫面
You can picture a beam of light setting off and travelling for a whole year without stopping. The length it covers is the light year — so large that stop being useful and the number stops feeling like a number. That is the quiet trick of the word: it names a gap too big to picture. Once a word carries that feeling, people borrow it for any gap they want to call enormous, whether the gap is in quality or in years.
可以想成一道光出發，不停地跑滿一整年。它跑過的長度就是一光年——大到公里已經不管用，數字也不再像數字。這個字最厲害的…更多收起
可以想成一道光出發，不停地跑滿一整年。它跑過的長度就是一光年——大到公里已經不管用，數字也不再像數字。這個字最厲害的地方就在這裡：它替一個「大到想像不出來」的距離取了名字。一旦一個字帶著這種感覺，人就會把它借去講別的差距。不管那個差距是好壞上的落差，還是時間上的遙遠，借過來就都變得很大。Two branches
借來形容「差太多」
這兩個說法都不再量太空。它們把那個大到想像不出來的長度借過來，用在別的差距上。一定用複數，語氣都偏口語，帶誇張。
noun · B2
Used with ahead of, better than or more advanced than to say that one person or thing is so far in front of another that the gap between them feels enormous.
遙遙領先；差了一大截