Humming deep space holds key to hidden black holes

Scientists have developed a new technology that can listen to background humming of deep space and unveil thousands of hidden black hole collisions missed by gravitational-wave detectors.

Deep space is not as silent as we have been led to believe. Every few minutes a pair of black holes smash into each other. These cataclysms release ripples in the fabric of spacetime known as gravitational waves.

The gravitational waves from black hole mergers imprint a distinctive whooping sound in the data collected by gravitational-wave detectors. The new technique developed by researchers from Monash University in Australia is expected to reveal the presence of thousands of previously hidden black holes by teasing out their faint whoops from a sea of static.

The first gravitational-wave was discovered in 2015, when ripples in the fabric of space time generated by the collision of two black holes in the distant universe were witnessed, confirming Albert Einstein’s 1915 general theory of relativity. To date, there have been six confirmed, or gold plated, gravitational-wave events announced by the LIGO and Virgo Collaborations.

The gravitational waves from these mergers combine to create a gravitational-wave background. While the individual events that contribute to it cannot be resolved individually, researchers have sought for years to detect this quiet gravitational-wave hum.