NANOGrav: Gravitational Waves (and other cool science) from Pulsar Timing

In 2023, NANOGrav and the rest of the pulsar timing array community announced strong evidence for the presence of a stochastic background of nanoHertz frequency gravitational waves. This has been the primary goal of the community for the past two decades, and it took thousands of hours of observations of many dozens of millisecond pulsars, and a highly sophisticated analysis effort to accomplish. In this talk I'll explain how these, and many other astonishing measurements, are all possible via the miracle technique of pulsar timing.