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.
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.
It turns out black holes make a low-pitched warbling sound that sounds (appropriately enough) like something from the soundtrack of a 1950s sci-fi B-movie.
It’s such a low-pitched sound that your ear wouldn’t be able to hear it naturally, so NASA used a process called ‘sonification’ to render it audible.
Gravitational waves and plasma waves (such as the solar wind, the stream of charged particles that’s constantly being emitted by our parent star) also present a medium through which sound is able to travel.
Not loudly enough that you’d be able to hear it were you there, but clearly enough for it to be detected by Earth-based radio telescopes.
So yes, space is mostly silent – but not truly silent.
