Supermassive black holes in galaxy centers draw closer like dancers in a crowd. But to start the waltz, they need more than a nudge from stars — they need a gas cloud. Otherwise, the cosmic gravitational hum would sound different. And that's a key to unlocking the growth of galaxies.
🎯 Supermassive black holes can be billions of times heavier than the Sun, but their mergers generate gravitational waves with periods of years — this 'hum' is detected by comparing the rhythm of pulsars across the entire Galaxy, which itself becomes a giant antenna.