A newfound gravitational wave ‘hum’ may be from the universe’s biggest black holes

The timing of pulses from dead stars hints at ripples in spacetime that are light-years long

An illustration of a pulsar.

Dead stars called pulsars (illustrated) emit beams of radio waves that sweep past Earth like clockwork. Gravitational waves from supermassive black hole pairs (upper left) are thought to ripple the fabric of spacetime and alter the pulsars’ timing.

Aurore Simonnet/Sonoma State University, NANOGrav

Beneath the explosions, collisions and other intermittent bangs in the cosmos, scientists suspect a nonstop soundtrack plays, created by ripples in spacetime continually washing through the universe.