Asked by Adam Lambert
If you were around in the 1500s, during the time of the Polish astronomer Nicolaus Copernicus, then the answer to this question would have been the Sun. Obviously, despite how we see the planets and stars moving across the night sky, our star is not at the centre of the Universe. So what is?
Today astronomers believe that there is no centre to the cosmos. You might think that there must be a central point – after all, the Big Bang must have started somewhere? While great explosions of say, a bomb, do start from one point, the Big Bang that is believed to have created our Universe nearly 14 billion years ago was a different matter entirely and appeared to happen everywhere all at once – time and space did not exist before the Big Bang and so there was no point from where it could have erupted from.
This does not mean that, if we were to see to the very edges of the Universe, that there would be more of it on one side of the Earth in comparison to the other. Imagine if you were small enough to stand on a balloon – small enough to see in a straight line across the balloon’s surface. You’re not able to see into or out of the balloon and, no matter which direction you look, the end of the balloon seems to be at roughly the same distance from you. If you start moving across the balloon’s surface, it would appear that you were at the centre of it. The reality of the matter is, however, that your two-dimensional balloon does not have a centre.
Now, suppose your balloon is being inflated with air and covered with pen marks around you. As the balloon gets bigger and bigger, these pen marks get further and further away from you and each other – no matter where you are it appears to you that you are at the centre of the expansion. Since space is curved, it is somewhat like the two-dimensional space on a balloon and just like there is no centre to its expansion there is no centre to the expansion of the Universe.
Answered by science journalist Gemma Lavender