Gravitational Tails: How Waves Leave Their Mark
Drop a stone into a pond — the ripples spread evenly and then fade. Gravitational waves born from black hole mergers behave differently: even after the main wave passes, a faint 'tail' remains. It's as if, after the ripples on the water, a tremor persists for a long time, caused not by the stone itself but by how the water 'remembers' the impact.