If the universe is 13 billion years old and Hubble can pick up images that come from 13 billion years ago, then logically there must be nothing further away than that. This is of course if we assume Earth to be the ground zero of the big bang.
If the earth were not ground zero for the big bang and the probability is it wasn't, then some point 6.5 billion years away could have been the ground zero so we should be able to see another 6.5 billion years away because of the different directions travelled.
However it is reasonable to assume the universe is not expanding at a uniform rate so every day the furthest point might get twice as far away, so the universe may only be 6.5 billion years old.
Or some supreme being could have created it all at around Wednesday 3:30pm August 17 4000BC
Eventually Hubble will be able to take a photo of the man who carries the sack that contains the whole universe including himself and the Hubble.
Utter twaddle the lot of it!