What does a black hole sound like? Both “creepy” and “ethereally beautiful,” according to people who’ve listened to an audio clip posted on Twitter by NASA. The U.S. space agency tweeted what it called a remixed sonification of the black hole at the center of a galaxy cluster known as Perseus, which lies about 240 million light-years from Earth. The sound waves identified there nearly two decades ago were “extracted and made audible” for the first time this year, according to NASA. The idea that