• Question: Do you have any idea how big space is ?

    Asked by oifeherb to Mark on 27 Apr 2020.
    • Photo: Mark Kennedy

      Mark Kennedy answered on 27 Apr 2020:

      That’s a very good question. First, let’s start with what we mean by the Universe. We think that the Universe is infinitely big – there are no sides to it, there are no edges, it goes on forever. So, that’s the easiest answer – it is infinite.

      However, that’s not the full story. There is very good evidence that the Universe is expanding. That is, every point in the Universe is slowly getting further away from every other point (so if you look at your hand, it’s actually ever so slightly further away from your eyes than it was a second ago, but the change is so, so small that you can’t see that). Because of this, and the fact that the Universe is only 13.6 billion years old, it means we can only see so far into the Universe before everything gets blocked.

      To try and visualise this, think of the surface of a bath that has a bubble in it. The surface of the bath is the entire Universe, and the Earth is the in middle of the bubble. On Earth, we can only see as far as the bubble (even though the surface of the bath is WAY bigger than the bubble). But, if you were able to blow air into the bubble, it would keep expanding, and you could see further and further into the Universe. We all this “bubble” the Observable Universe. So, the size of this “bubble” is roughly 93 billion light years, or:

      880,000,000,000,000,000,000,000,000 meters.

      I hope that helps answer your question, and thank you for asking it.