When looking at the night sky, we see lots of stars. Several places tell you that the light of those stars has traveled to many light years to reach Earth and there may be others where light has not made it here yet. How can this be?
Assume we accept the Big Bang Theory that suggests the universe began in a single point (or at least very small space). When the "bubble" that is the universe reaches 1 light year in diameter, the light from one end should have been shinning the whole time, so the other side should still be able to see it. Continue on until the Universe is at present size, and the light should still be visible by the same logic.
So how can there be systems from which light has not reached us yet?