• Question: If the universe is expanding, what is it expanding into?

    Asked by JazzTea to Stewart, Miriam, Marton, Laura, Kathryn, David on 13 Nov 2018. This question was also asked by Anonymous.
    • Photo: David Ho

      David Ho answered on 13 Nov 2018:

      This is a great question. The answer takes a bit of getting your head round — the universe isn’t expanding into anything, because space itself is getting bigger. It’s like the fact that it’s meaningless to talk about “outside” the universe, because the universe is the word we use to describe everything we can observe. When we say the universe is expanding, what we mean is that points in space get further and further apart as time goes on. So a faraway galaxy will be even further away in a hundred million years time than it is now.

    • Photo: Stewart Martin-Haugh

      Stewart Martin-Haugh answered on 13 Nov 2018:

      David gave a great answer.

      This is one of the cases where how you think about the world around you can make things in physics more confusing: sometimes it’s useful to relate things to everyday experience, and sometimes it’s just confusing!

    • Photo: Miriam Hogg

      Miriam Hogg answered on 13 Nov 2018:

      David answered this fantastically.

      I think the confusion happens because people often say the universe is like a bubble or balloon blowing up so we’re thinking about it in the wrong way. There is no outside. The universe is where all the matter and laws a physics are, without those things there is nothing! It’s hard to imagine, its a bit like trying to think about infinity, humans brains don’t like the idea.