If Space is a vacuum with nothing in it, then what would the edge of the universe even mean

Question

…it would be a ‘border’ between nothing and nothing?

In: Planetary Science

Answer 1

I don’t think there is an ELI5 explanation for this. What I can tell you is that there are two concepts of “nothing” in this context. The first definition is the one where nothing has no properties at all: no mass, no charge, no dimensions, no space or volume, etc. It’s legitimately nothing. The second definition of nothing is empty space. Empty space has a volume and certain physical properties. The scientists of old might have called this empty space “aether,” while the modern day scientists call it space time. It has properties that can be measured and can interact with objects. Whatever it’s made of, it isn’t truly nothing because it has physical dimensions and physical properties. Theoretically it can be traversed whereas the first definition of nothing cannot be.