# I Does the Universe have a centre, yes or no?

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1. Jul 4, 2016

### KoenGerits

Does the universe have a literal centre (i.e. a physical point in space where the distances to the edges of the universe in all directions are equal)? Assuming the universe isn't infinite, which would make it far easier to understand that it doesn't have a centre, or is a 2d sphere like the skin of a balloon. Just to clarify: I'm not asking about the centre of the expansion of the universe. I understand that space itself is what's expanding, not the matter inside of it.

I hope someone can help me out,

Thanks!

2. Jul 4, 2016

3. Jul 4, 2016

### KoenGerits

Well... wow. I can see that I'm surely not the only one breaking my head over this. Thanks!

4. Jul 6, 2016

### grauitate

I'd like to imagine the situation as follows, as quoted often before but here maybe more radically:
No, the universe has no center, i.e. similar as there is no center on the curved surface of a ball, there is no center in the curved volume of the universe. This is valid for a stationary closed universe as well as for an apparently (quoting Hubble) expanding universe. Every observer at any point and at any time would see (in the mean) the same horizon with galaxies of growing redshift z and the blackbody-background radiation at 2,75 K.
Further more, e.g. an observer A on a galaxy A who observes a galaxy B at redshift z = 10 is as well observed by an observer B on galaxy B at redshift z = 10.
So, any observer A and B at any time have "equal rights and equal duties": Being an observer he or she feels as being in the center, contrarywise being observed he or she is in the distance or at the "edge" for the other far distant observers.
I think this is quite nice conceivable and provides interesting consequences (but I did not check, if it meets the current theory of standard cosmology).

5. Jul 6, 2016

### Alltimegreat1

Well these are all theories aren't they. We don't know for sure that the universe is completely flat. If it is not, it could be bounded with a physical border at the edges and a center.