No really, by our current definition of 'void', does a void move or is its position and shape solely defined by the objects moving into and around it? Separately, is the void inside the universe the same as the void outside the universe, or is it fundamentally different somehow?
I don't expect we'll ever answer the second question, but the first is able to be answered by how we choose to define the term 'void'.
>Separately, is the void inside the universe the same as the void outside the universe, or is it fundamentally different somehow?
By definition they are different. Voids, as I said, are areas within the universe that have relatively less matter density. Key thing being that they are part of the universe, whereas 'outside the universe' is, well, not part of this universe.
I think that was exactly the point that your parent https://news.ycombinator.com/item?id=32342806 was making:
> Does a void move? No really, by our current definition of 'void', does a void move or is its position and shape solely defined by the objects moving into and around it?
That is, I think that they were not asking a factual question—"obviously voids can move, but do they?"—but rather a sort of ontological question—"does it even make sense to ask whether voids move?"—just as you are.
Of course, I'm almost certainly wrong on both accounts.