# Mutually inaccessible galaxies

It is said the farthest galaxy we can see in one direction is beyond the cosmic horizon of the farthest galaxy we can see in the opposite direction; they can't see each other. Doesn't this contradict the law of addition of velocities? The sum of two velocities cannot be greater than $c$ in our frame, and so the mutual velocity also cannot be greater than $c$, using the addition law again.