This is called the “lookback time”, and it's a cru cial tool for cosmology: by observing very distant objects, we can see the Universe when it was young!
这叫做“回溯时间”,是宇宙学的一个重要工具:通过观察非常遥远的物体,我们可以看到宇宙年轻时的样子!
经济学人(汇总)
Since four-fifths of the world's potash is traded internationally, the impact of price spikes will be felt in every agricultural region in the world, warns Humphrey Knight of cru, a consultancy.