We know that the universe is expanding,but do we know from which point it is expanding outwards?
Please read the FAQ in the cosmology section along with several of the threads on this exact subject. The short answer is that there is no center. If you were 5 billion light years from Earth you would observe the universe expanding away from you exactly like we see it expanding for us here.
Think of it as if you were on the surface of a balloon, where the only access is the surface, you can't access inwards to the center, so any place on the surface of the balloon can be thought of as the center, lines leading away will converge at the other side but that happens no matter where you are on the balloon.
So the universe is like that but on a higher dimensional reference. That's about as close an analogy as I can come up with.
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