[In Depth] In search of spacetime megawaves
Last month, the detection of gravitational waves from merging black holes made headlines and tweetstorms around the world. But a hunt for much bigger game was already afoot. The black holes responsible for last month's discovery weighed a few dozen times as much as our sun. Black holes millions or billions of times that massive, however, lurk at the centers of most galaxies—and they merge, too, creating waves like gravitational tsunamis. Three teams of radio astronomers are watching the heavens for hints of these megawaves, which should cause hiccups in the ultraregular pulses of distant energy beacons called millisecond pulsars. The researchers' latest results suggest that increasing sensitivity should enable them to see signs of the waves sometime in the next decade. Author: Daniel Clery