What Is The Sound Of A Black Hole?
QUICK ANSWER
NASA released audio of a supermassive black hole at the center of the Perseus galaxy cluster in May 2022. The sound comes from pressure waves rippling through hot gas around the black hole. The original frequency is 57 octaves below human hearing, so NASA scaled it up dramatically to make it audible.
Sound usually doesn't exist in space because there's no air for sound waves to travel through. But near a supermassive black hole at the center of a galaxy cluster, there's enough hot gas for pressure waves to propagate. NASA discovered such waves around the Perseus cluster black hole in 2003, and released audio of them in 2022 by scaling the frequency up dramatically.
Do black holes actually make sound?
Yes, but only in places with enough gas to carry it. According to NASA, the popular idea that there's no sound in space is true for most of empty space, but galaxy clusters contain copious amounts of hot gas that can carry pressure waves. The supermassive black hole at the center of the Perseus galaxy cluster generates such waves, which NASA's Chandra X-ray Observatory detected starting in 2003. The waves are real sound, just at frequencies far below what humans can hear.
What does the Perseus black hole sound like?
Eerie and haunting, when scaled up to audible frequencies. NASA released the sonification in May 2022 as part of Black Hole Week. The audio scales the original frequencies up by 57 and 58 octaves to bring them into human hearing range, that's 144 to 288 quadrillion times the original pitch. The result sounds like a low, wailing drone, with some comparing it to whale calls or ghostly howls. It went viral when released and has since been featured in BBC and Netflix documentaries about space.
How was the sound captured?
Through years of X-ray observations. The Chandra X-ray Observatory detected ripples in the hot gas around the Perseus cluster's black hole over decades of observation. The ripples are sound waves, propagating outward from the black hole at the speed of sound through the cluster gas. The black hole's activity creates the waves through periodic outbursts, with each ripple representing a cycle of compression and expansion in the surrounding gas. The original frequency works out to about one cycle every 10 million years.
Can other black holes be heard?
Yes, NASA has sonified several. After Perseus, NASA released sonifications of the M87 supermassive black hole and others. Each black hole produces a different sound based on the gas, accretion patterns, and other local conditions. The sonifications aren't direct sound recordings (which would be impossible across millions of light-years) but translations of measured data into audio. They've become popular ways to experience black holes through senses other than sight.
Black holes can make sound when there's enough gas around them to carry the pressure waves. NASA released audio of the supermassive black hole at the center of the Perseus galaxy cluster in 2022, scaling the original frequencies up 57 octaves to make them audible. The result is an eerie, haunting drone that went viral when released. Sonifications offer a new way to experience the universe beyond the visual.
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