Sean Carroll in Preposterous Universe:
Human civilization is only a few thousand years old (depending on how we count). So if civilization will ultimately last for millions of years, it could be considered surprising that we’ve found ourselves so early in history. Should we therefore predict that human civilization will probably disappear within a few thousand years? This “Doomsday Argument” shares a family resemblance to ideas used by many professional cosmologists to judge whether a model of the universe is natural or not. Philosopher Nick Bostrom is the world’s expert on these kinds of anthropic arguments. We talk through them, leading to the biggest doozy of them all: the idea that our perceived reality might be a computer simulation being run by enormously more powerful beings.