:)

Outer space isn’t a perfect vacuum. Even the most desolate stretches of space contain a few atoms per cubic centimeter. The sound waves coming from the singing black hole were traveling through the hot gases that fill the Perseus galaxy cluster (where this particular black hole is located).

I have come across this fact a couple times recently, and it leaves me a bit confused. I was under the impression that sound waves cannot travel through the vacuum of space (I think read that in an article in an old issue of Mental Floss about the physics of Star Trek?). The above fact seems to contradict that, can someone please explain so I’m not confused anymore? please and thank you!! :)