Question

Where does the universe end?

Answer 1

Border of the observable universe is about 46 billion light years away.

Explanation:

Unfortunately, the universe is expanding so fast that it is almost limitless from our perspective. We really only know that the observable distance is 46 billion light years.

How could this be if the universe itself is not that old?

What this means is that the light was actually 13.8 billion light years away, but while it came towards us, the universe was expanding, so the light ended up traveling 46 billion light years to get to us.

read this for more info
https://phys.org/news/2015-10-big-universe.html