At the dawn of the twentieth century, Einstein revolutionized our conception of reality, showing that space and time are not merely the stage on which the show unfolds, but dynamical entities that stretch, bend, and vibrate to give rise to the force we know as gravity. A century later, the vibrations of spacetime have been directly detected as gravitational radiation from colliding black holes, confirming Einstein’s prediction and ushering in a new era in observational astronomy. How did physicists measure these minuscule vibrations, and what does it mean for our understanding of the universe? And what is the next revolution, fomenting right now, in our conception of space and time?