>How does something infinite "expand" though? It's not expanding into anything, because it's infinite. I’ve found it easiest to think of this in one dimension

>How does something infinite "expand" though? It's not expanding into anything, because it's infinite. I’ve found it easiest to think of this in one dimension first. Imagine a number line. It’s infinite in both directions, in the sense that you can move along it and never reach an end. Suppose we’re sitting at X=0 and look in the positive direction at X=1. That point is distance 1 away from us. Look the other way at X=-1, and that point is distance 1 away, too. Now let’s multiply the number line by 2. The point that used to be 1 is now 2, and 2 is now 4. 0.5 is now 1. Look in both directions, and it’s still infinite by the same definition; you can travel in either direction and never reach an end. We’re still at X=0 and look in the positive direction. The point that used to be 1 is now distance 2 away. Same with what was previously -1. There’s nothing special about the location at the origin either. If we had originally sat at X=10 and looked at X=11, we’d now be at X=20 and looking at X=22: a distance of 2 away. In this way, every point has an equal claim to being the “center of expansion.” In one dimension, this is equivalent to saying that “space expanded,” it was infinite before, and it’s infinite after expansion.