Current evidence indicates that the universe is "flat", which like "open", means that it is boundless (essentially infinite). Based on the finite speed of light, our "visible universe" (what we can see based on what light is available to us) is about 13.7 billion light years in every direction. So, our "visible universe" has a diamter of about 27.4 billion light years. Our visible universe grows by 1 light year per year. The whole universe is bigger than that. With Big Bang theory, you would expect that our visible universe is a typical slice of the whole universe. Of course, there are no actual observational data available outside of our visible universe, so there is some uncertainty in that. Anyway, an astronomer 13 billion light years away from us could see an additional 13 billion light years further IN THAT DIRECTION from us. He/she/it could no see the 13 billion light years of stuff on the other side of us that we can see.