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

    Asked by SofiaB on 6 Mar 2026.
    • Photo: James Lazenby

      James Lazenby answered on 6 Mar 2026:

      I’m not a physicist, but did study physics so I’ll give it a go at explaining it. My physics professor once said the more you try and understand astro-physics the more you realise you don’t understand it.

      The universe is defined as everything, so there is nothing for the universe to expand into. So the universe is expanding into itself. Picture an un-inflated balloon and you draw dots on it. As you blow the balloon up, the dots will get larger and further away from each other as they expand, but the matter that made up that balloon is still the same, the distances have just increased. That’s how we know the universe is expanding. Looking at galaxies light years away we see evidence of them getting further away because the spaces between us are getting larger, but nothing extra is being added.

    • Photo: OLUWAROTIMI MICHAEL POPOOLA

      OLUWAROTIMI MICHAEL POPOOLA answered on 9 Mar 2026:

      The universe is not expanding but space does.

Comments

  • Photo: Cora U

    Cora U commented on :

    I like the answer I heard from a colleague in a public talk. The Universe isn’t really expanding into anything larger (as it is all there is), but you could say that it is expanding into the future. This is because we cannot treat space and time as separate but instead as one spacetime.