Simulations and Reality in WYSIWYG Universes

Pondering about the nature of the universe is always fun. So, this Oxford philospher "proves," mathematically, that either you're living in a simulated universe, or else the world is going to end soon. Wow, that's bleak, isn't it? Fortunately there are some flaws in his logic, leading to some even more fascinating ideas, which I've played with for fun in an article that was originally printed in the Bulletin of the Science Fiction and Fantasy Writers of America. Enjoy it before the universe ends! :)