Note that in a closed universe you could start a journey off in one direction and, if allowed enough time, ultimately return to your starting point; in an infinite universe, you would never return.

请注意，在一个封闭的宇宙你可以朝着一个方向开始旅行，如果允许足够的时间，最终将返回到出发点；而在一个无限的宇宙中，你永远不会回来。

youdao

If the universe has a positive curvature, it's a closed universe.

正曲率的宇宙是封闭的宇宙。

youdao

Let's say we start in a universe that, at some particular moment, has no closed timelike curves.

我们在宇宙中是以一些特定时刻来起始的，没有封闭的时间型曲线。

youdao