1. Time exists.
时间确实存在。

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.
如果你觉得这个问题太过普通，大可以跳过它。时间当然存在——否则我们怎么上闹钟呢？时间将宇宙有序地组织起来——谢天谢地，否则我们的世界就会乱成一锅粥了。真正的问题其实是：时间究竟是我们这个宇宙的基本组成要素，还是只是偶然出现的。我们曾以为“温度”是自然的基本要素之一，但现在我们知道它其实是原子运动的附加产物。而对于“时间是否是宇宙的基本要素”，回答是：没人知道。我认为它是，但要确认这一点，我们得先对量子引力有更好的理解。