When two black holes collide, the noises scientists hear are birdlike.
This morning, scientists from the Laser Interferometer Gravity Observatory announced that LIGO had detected gravitational waves from the collision of two black holes, an event so cataclysmic that it converted the mass of three solar systems into pure energy in about a tenth of a second.
Scientists have been trying to figure out how to “listen” to gravitational waves—and to prove their existence—ever since Einstein predicted them in 1915. But until September 14, 2015, when the colliding black-hole event was first detected, this was beyond our technical abilities. In the words of Scott Hughes, “Gravity is a weak force. Measuring these things is bloody hard.”
Hughes is a theoretical physicist at MIT who has been contemplating LIGO since its inception in 1992. He has struggled with a question at the heart of the observatory program: Once we do hear gravitational waves, how will we know where they come from? How can we use them to explore the mysteries of the cosmos? To this end, Hughes has modeled the “sounds” of a host of astrophysical events, including colliding black holes. (You can listen to his impressions of these sounds below.)