We’re told there’s no sound in space; that it’s silent. But is that strictly true?

By Russell Deeks

Published: Saturday, 09 December 2023 at 08:33 AM


Is space silent? Well, you’re not going to need ear-defenders, put it that way!

The simple answer here, of course, is yes: space is silent because it’s a vacuum.

After all, what our ears perceive as ‘sound’ is just a pressure wave that passes through a medium, be that medium a solid, liquid or gas, and agitates the molecules within it.

When that pressure wave hits our ears, it causes small hairs and bones within them to vibrate, which sends an electrical signal to the brain that we interpret as sound.

Soundwaves hit our ears, which our brain interprets as sound. Credit: Jun / Getty Images

But in a vacuum, where there are no molecules of liquid, solid or gas to agitate, that can’t happen – so there is no sound.

But when you’re talking about space, the simple, easy answer is seldom entirely correct – and that’s the case here, too.

That’s because space isn’t actually a vacuum at all.

Yes, huge regions of it are, particularly in interstellar and intergalactic space.

But within galaxies and nebulae are huge, swirling clouds of gas and dust, and the molecules within those clouds are just as capable of being agitated and so passing on a pressure wave – ie, sound – as their counterparts here on Earth.

As if to prove the point, in 2022 NASA released a sound recording of a black hole, extrapolated from observational data from the Chandra X-Ray Observatory.