According to Einsteins Theory of Relativity, the maximum speed in the universe is light velocity. But let's imagine a space ship - if it was possible - running at this limit speed in one direction in deep space, and other, at the same speed and time, running to the right opposite side. Aren't they going over that speed limit, in relative velocity to each other?

Now you can also imagine a very very far way galaxy, that is moving in deep space and withdrawing very fast from our Milk Way Galaxy. If the relative velocity of each other are over the light speed we will never be able to find and see that far way galaxy.