Astrophysics Colloquium - You cannot find what you do not look for, or Welcome to gravitational-wave astronomy

The first decade of gravitational-wave astronomy has proceeded in the grand tradition of all good science, i.e., not as anyone expected. I will summarise what we have, and have not, learned. I will then look to the next two decades, when the science potential will increase dramatically, but so will the challenges. I will discuss three: theoretical calculations of an entirely new population of black-hole binaries, the ever-growing scourge of systematics, and the dream of discovering new sources and new physics.