1. Time exists.
時間確實存在。

Might as well get this common question out of the way. Of course time exists — otherwise how would we set our alarm clocks? Time organizes the universe into an ordered series of moments, and thank goodness; what a mess it would be if reality were complete different from moment to moment. The real question is whether or not time is fundamental, or perhaps emergent. We used to think that "temperature" was a basic category of nature, but now we know it emerges from the motion of atoms. When it comes to whether time is fundamental, the answer is: nobody knows. My bet is "yes," but we'll need to understand quantum gravity much better before we can say for sure.
如果你覺得這個問題太過普通，大可以跳過它。時間當然存在——否則我們怎么上鬧鐘呢？時間將宇宙有序地組織起來——謝天謝地，否則我們的世界就會亂成一鍋粥了。真正的問題其實是：時間究竟是我們這個宇宙的基本組成要素，還是只是偶然出現的。我們曾以為“溫度”是自然的基本要素之一，但現在我們知道它其實是原子運動的附加產物。而對于“時間是否是宇宙的基本要素”，回答是：沒人知道。我認為它是，但要確認這一點，我們得先對量子引力有更好的理解。