The Fermi Paradox - Tim Urban. Stick-figure-enhanced explainer on why we’re seemingly alone in a universe that should be teaming with life according to the Drake equation.
Dissolving the Fermi Paradox - Anders Sandberg, Eric Drexler, Toby Ord. Revisits the problem to show that the paradox goes away if we slightly change the assumptions in the Drake equation.
Doomsday Argument, The Anthropic Bias - Nick Bostrom. Explains anthropic reasoning and what our human position in the universe can tell us about our chances for survival.