And, as has been said elsewhere, inflation. The speed of light is the ultimate speed limit for travelling through space-time. Space-time itself can expand at whatever damn speed it feels like, apparently.

Inflation is a great theory, because it makes other problems go away, leaving you only with the problem of how the feck inflation could have happened. This is why you should love cosmology.

Sometimes I wish I'd actually done some work and been a proper scientist, instead of getting all my information from The Sky At Night.