This is what a black hole sounds like 

If the Battlestar Galactica universe was real and you were a Cylon living in The Colony, which is right on the edge of a black hole, what would you hear?

Never mind anything that close to a black hole would be overcome by the beast’s gravity and fall towards its gaping maw — if it wasn’t already crushed. NASA’s Chandra X-ray Observatory was able to “hear” a black hole in the Perseus galaxy cluster through the detection of pressure waves that cause ripples in the cluster’s hot gas, but it was at a pitch way too low for human ears to make out (no word on what Cylons might have been able to pick up). Now NASA scientists have translated that data into a sound we actually can hear, and it’s spooky.

The black hole lurking in Perseus was previously known to produce some kind of sound. While there have been sonifications for other black holes, and a new one for M87, the first whose glowing accretion disc was ever imaged, this stands out because it is based on the actual sound waves that showed up in the data. Sound waves are pressure waves, so the idea really isn’t too far out. Visualization scientist Kimberly Arcand of the Chandra X-ray Center (CXC) was involved in morphing an inaudible noise from space into something that could have come off an ambient soundtrack for a haunted house.

“This project is a whole other way to translate ‘invisible’ X-ray data,” she told SYFY WIRE. “It showcases a unique approach to processing data about sound through sound, almost 20 years later, to help add new value for the scientific findings.”

Astronomers detected sound waves coming from Perseus in 2003, more proof that space has its own peculiar music, when they were found to be the equivalent of a note 57 octaves below middle C. The human ear is only capable of hearing 10 octaves lower than middle C. It used to be thought that space was silent. Now we know that phenomena such as gravitational waves, and even primordial sounds from the dawn of the universe, can be “heard” by telescopes. Galaxy clusters are ideal for the propagation of sound waves. The gas of hundreds of thousands of galaxies within such clusters creates a medium for those waves to travel through.

Along with astrophysicist Matt Russo and musician Andres Santaguida of SYSTEM Sounds (who were behind sonifying TRAPPIST-1, the Moon, our own black hole, and exoplanets), Arcand and her colleagues were able to make the voice of a black hole heard by loading the original data into python for translation. Think of it as the sound equivalent of a 2D image. There may be separate pieces of data, but just as data can be combined into images like a heat map of Venus or the inside of Mars, the same thing happens when sound information is put together. You get a soundscape instead of a landscape. Each black hole sonification has something different to say (or sing).

"With the black hole in Perseus we had a clear opportunity to let it have its grand moment on the stage with a deep bass solo, those eruptions as found in the X-ray data,” Arcand said. “With the data of M87, we were telling the story of the supermassive black hole’s jet.”

Sound waves that had gone unheard before were scaled up by 57-58 octaves, which made their frequency 144 and 288 quadrillion times higher. Watch the video above and you’ll see what looks like a radar scan. It shows waves emitted from different directions, while Chandra X-ray data is visible in cool blues and purples. Now watch and listen to the M87 black hole video below. This one, whose data was captured by several different telescopes, could fit into the soundtrack of a sci-fi show like Battlestar Galactica better than that of a haunted house.

The M87 black hole sounds like emergence. If that makes any sense to those of you out there who also have synaesthesia, it is the music of a jet emerging from the bowels of darkness and journeying into space. You can even see the sound going in that direction. The Event Horizon Telescope, whose visualization of this black hole almost broke the internet in 2019, didn’t actually supply the data for this one. The three panels you see represent X-rays captured by Chandra (highest tones), optical light (medium tones) from Hubble, and radio waves (lowest tones) from ALMA.

Arcand is excited for future projects that will bring the sounds of space to your EarPods. She and her colleagues have been using sonification techniques to look into star cluster and galactic geometries, and also adding sound to 3D astrophysical data, which could even be incorporated into virtual reality or augmented reality so it could be studied further.

“I’m just looking for data sets, or stories, where the sonification can add to the information quotient and the overall value of the experience,” she said. “That could mean uncovering science of interest, elucidating some nuance, or helping to make science come alive.”