Comment What does a black hole sound like? Both “creepy” and “ethereally beautiful,” according to people who have heard an audio clip tweeted by NASA. The US space agency tweeted what it called a jumbled echo of the black hole at the center of a galaxy cluster known as Perseus, which lies about 240 million light-years from Earth. Sound waves detected there nearly two decades ago were “extracted and audible” for the first time this year, according to NASA. The 34-second clip set social media ablaze, with many people freaking out that anything, let alone what sounds like an eerie, dull moan, could escape a black hole. But the idea that there is no sound in space is actually a “popular misconception,” the agency said. While most of space is a void, with no medium for sound waves to travel through, a galaxy cluster “has abundant amounts of gas surrounding the hundreds or even thousands of galaxies within it, providing a medium for sound waves to travel through.” explained. The misconception that there is no sound in space comes because most of space is a vacuum, providing no way for sound waves to travel. A galaxy cluster has so much gas that we’ve captured the real sound. Here it is amplified, and mixed with other data, to hear a black hole! pic.twitter.com/RobcZs7F9e — NASA Exoplanets (@NASAExoplanets) August 21, 2022 The clip, which NASA described as a “Black Hole Remix,” was first released in early May to coincide with NASA’s Black Hole Week — but a tweet on Sunday from NASA’s exoplanet team seems really incredible, with the clip has been viewed over 13 million times. The sound waves were discovered in 2003 when, after 53 hours of observation, researchers at NASA’s Chandra X-ray Observatory “discovered that pressure waves emitted by the black hole caused ripples in the cluster’s hot gas that could translate into a note. “ But people couldn’t hear that note because its frequency was too low — equivalent to a B-flat, about 57 octaves below the middle note of a piano, according to NASA. So the astronomers on Chandra remixed the sound and increased its frequency by 57 and 58 octaves. “Another way to put this is that they sound 144 quatrains and 288 four billion times higher than their original frequency,” NASA said. ‘Incredible’ images of Jupiter revealed by NASA’s James Webb Telescope Kimberly Arcand, principal investigator of the sonification project, said that when she first heard the sound in late 2021 – which she described as “a beautiful Hans Zimmer score with the moody level on a very high level” – she was blown away. “It was a wonderful representation of what was in my mind,” the visualization scientist and head of emerging technology at Chandra told the Washington Post. But it was also a “tipping point” for the ultrasound program as a whole, as it “really sparked people’s imaginations,” he said. It also indicates future areas of research. “The idea that there are these supermassive black holes sprinkled throughout the universe that … perform incredible songs is a very tempting thing,” Arcand added. A deep voice from deep space Experts have warned that the sound in NASA’s remix isn’t exactly what you’d hear if you were somehow standing next to a black hole. Human ears would not be “sensitive enough to pick up these sound waves,” Michael Smith, a professor of astronomy at the University of Kent in England, told The Post. “But it’s there, it’s the right kind of frequency, and if we amplified it … then we could hear it,” Smith said. He likened it to a radio — “you turn up the volume, it’s louder, and then you can hear it.” Arcand said the idea took shape during the coronavirus pandemic. He was working on converting X-ray light captured by Chandra’s orbiting telescope into images, including creating 3D models that could be printed to help people with low or no vision access this data. When the pandemic hit, this schedule became difficult to maintain remotely. So, along with other colleagues, she decided to try something new: sound editing, or the process of translating astronomical data into sound. The team included experts who are blind and inspired Arcand to “think differently” about the value of translating complex data sets into sound. Looking at 2003 data on the Perseus galaxy cluster, she and her colleagues worked to determine the properties of the pressure waves and infer the sound they would produce, then increased their frequency. The decision to release the “re-recording” of nearly two decades of data is part of the organization’s efforts to use social media to communicate complex scientific discoveries in plain English to its millions of followers. Through a partnership with Twitter, NASA discovered that “while fans were enjoying amazing space photos and behind-the-scenes missions, there was a group of people who wanted to know what space sounded like,” the company wrote in a press release. Some experts said the clip was confusing because it gave the impression the sound “was somehow what you would hear if you were there,” Chris Lintott, a professor of astrophysics at the University of Oxford, tweeted on Tuesday — as if you had a device recorder that directly translates the sound from the galaxy cluster to Earth. “Recording data is fun and can be useful — especially for those who may not be able to see images. But sometimes it’s used to make things look ‘deeper’ than they are, like here,” Lintott added. But Smith, the University of Kent professor, said “it makes perfect sense to say that there are sound waves [in the galaxy cluster]and if we were there, we could hear them if we had ears sensitive enough.” However, he acknowledged, “these galaxy clusters are so far away, they have to make a lot of assumptions to turn it into what we could hear if we were there.” Arcand said she understood criticism from some quarters that soundization risks oversimplifying a complex process — particularly because the combination of pressure, heat and gas that enables sound waves inside the Perseus galaxy cluster is specific to that environment. But the value of recording, she said, is that it made her “question things in different ways.” “It’s a great representation of science, in my opinion, and a rather haunting sound!” Carole Mundell, head of astrophysics at the University of Bath in England, told The Post via email. Supermassive black hole seen at the center of our galaxy The project, and NASA’s tweets about it, seem to have accomplished the space agency’s mission to share its science and research with the general public in a conversational way — though not everyone was a fan of the remixed black hole sounds. On the Internet, people were both excited and horrified by it, drawing colorful comparisons to the Lord of the Rings and Silent Hill series. Others have had fun with the audio clip, overlaying an image of an intergalactic puppy over it or mixing it with a recreated sound believed to be closer to a mummy’s voice. “I can confirm that the black hole noise released by Nasa is the sound of hell,” wrote one darkly humorous Twitter user. Another said: “New genre just released: Cosmic Horror.”
