有人會(huì)問：你怎么知道宇宙的年齡有137億年了？137億年前又沒你。你不必一定是天文學(xué)家，當(dāng)我們抬頭仰望夜空，我們所看的星光是從幾百萬光年遠(yuǎn)的地方射過來的，也就是這些光要花幾百萬年才能到達(dá)地球。因此如果你足夠遠(yuǎn)，你就能看到宇宙初期的情景。



聽寫方式: 全文聽寫。
Hint:
Big Bang
light-year

訂閱后不但能收到及時(shí)通知，還能看到列表哦。
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.