What Space Really Sounds Like (Mostly Nothing)

Why it's quiet

A sound is a push that gets passed along from one bit of stuff to the next. With no stuff, nothing gets passed along. NASA says it this way: "most of space is essentially a vacuum, providing no medium for sound waves to propagate through".

The film Alien turned that into one of the best-known lines in science fiction. Its poster said: "In space no one can hear you scream." That was 1979.

The catch

NASA also calls the idea that there's no sound in space a "popular misconception". Not all of space is empty. A cluster of galaxies is filled with thin gas, and gas can carry a sound wave.

In May 2022 NASA released the sound of the black hole at the centre of the Perseus galaxy cluster. Astronomers had found pressure waves rippling out through the cluster's gas in X-ray telescope data. Those ripples are sound in the proper sense.

You couldn't hear them if you were there. NASA says the note sits "57 octaves below middle C". To make it audible they shifted it up by 57 and 58 octaves. For scale, a whole piano keyboard covers a little over seven.

So even the one true sound of space I found is a translation.

What should a Space world sound like, then?

This was my problem when I built the third world in my app. I couldn't copy the real thing, because the real thing is silence.

What I could work from was the feeling. I asked what a big empty place would feel like, and tried to build that feeling out of sound.

• Gaps. Fewer sounds are allowed to play at once in Space than in the other two worlds, and there is a forced pause between the bigger events. Emptiness is something you can hear.
• Nothing to stand on. Space has no pulse at all. Its notes all belong to one wide, open chord, so nothing pulls toward an ending and nothing clashes. It began on a scale with no home note: more on that in whole tones have no home.
• Distance. There is almost no room sound, because space has no walls. In its place is a long echo. A sound leaves, and a few seconds later it answers from far away. The echo itself drifts: how long it takes, how often it repeats and how loud it is all wander slowly, and sometimes it nearly disappears.
• A radio, not a landscape. The sounds are the kind a radio picks up between stations: faint static, soft crackle, slow humming tones, a rising whistle, a short run of beeps. Nothing ever becomes a song. The quiet between signals is as much a part of it as the signals.

None of this is what space sounds like. It's what being alone in a huge empty place might sound like, if it sounded like anything. I think that is a fair thing to build, as long as I say so.

Space is one of the two paid worlds. Ocean is the free one.

Sources

• New NASA Black Hole Sonifications with a Remix, NASA
• Alien (film), Wikipedia