• Question: As the universe expands, do we expand with it as well?

    Asked by Harry Oo to Jillian, Connor on 21 Jun 2015.
    • Photo: Connor Macrae

      Connor Macrae answered on 21 Jun 2015:

      Some people argue that as space-time is expanding with the universe, then so are we. But, physically, we are not expanding, we are a fixed point of mass. However, when we look at galaxies, we see they are on average moving away from us – and the most distant galaxies are seen to be moving the fastest!

    • Photo: Jillian Scudder

      Jillian Scudder answered on 21 Jun 2015:

      This is an important subtlety you’ve hit on! The universe is indeed expanding, but it’s more that the space between objects is expanding. However, there seems to be an exception for regions of space that are very tightly controlled by gravity, like the solar system – those regions are hard to stretch because the gravitational pull is so strong in the opposite direction. So our solar system isn’t expanding, but the distance between our cluster of galaxies and the next cluster over – where gravity can’t hold things together – is expanding.