有人会问：你怎么知道宇宙的年龄有137亿年了？137亿年前又没你。你不必一定是天文学家，当我们抬头仰望夜空，我们所看的星光是从几百万光年远的地方射过来的，也就是这些光要花几百万年才能到达地球。因此如果你足够远，你就能看到宇宙初期的情景。



听写方式: 全文听写。
Hint:
Big Bang
light-year

订阅后不但能收到及时通知，还能看到列表哦。
People ask the question, "How do you know that the universe is 13.7 billion years old? I mean, smarty-pants, you weren't there 13.7 billion years ago." Well, when you watch television on videotape, you hit the stop button when you see an explosion, and you can run it backwards and see when it actually took place. The same thing takes place with cosmology. We can run the videotape backwards and then calculate when it all came from a cosmic explosion. You don't have to be an astronomer to look back in time. If you gaze up at the night sky, you're seeing stars that are millions of light-years away, meaning it took the light from those stars millions of years to get here. So if you look far enough, you should be able to see the beginning of the universe.