I don't remember who authored the following, but I thought it was amusing enough years ago to toss it into my interesting-quotes.txt:

I recall reading a science fiction story that involved the first human spaceship to reach the edge of the universe. When they tried to go through they bounced off, it was impenatrable.

Then we cut to 2 higher dimensional beings, and one says, "On that run it took life only 14.7 gigayears to reach the edge."

The other one says, "Great! Let's do another run. Sterilize the medium."