"If you listen closely some morning, when the sun swells
Over the horizon and the world is still and still asleep,
You might hear it, a faint noise so far inside your mind
That it must come from somewhere, from light rushing to darkness,
Energy burning towards entropy, towards a peaceful solution,
Burning brilliantly, spontaneously, in the middle of nowhere,
And you, too, must make a sound that is somewhat like it,
Though that, of course, you have no way of hearing at all."
From George Bradley's 1986 poem “The Sound of the Sun," in full here.
Related: Astrophysicist Janna Levin's 2011 TED talk, "The Sound the Universe Makes," visualizing the tympanic rumbling of black holes. Although we're sure the universe isn't silent, we don't have any good recordings of it--the waves simply have too far to travel.
Levin is optimistic: "Imagine a billion years ago, two black holes collided. That song has been ringing through space for all that time. We weren't even here. It gets closer and closer -- 40,000 years ago -- we're still doing cave paintings. [...] Whatever year it will be when our detectors are finally at advanced sensitivity, we'll build them, we'll turn on the machines, and, bang, we'll catch it -- the first song from space." It seems that sound can't disappear. It's just a matter of when it will reach us, and the sounds from the start of the universe will reach Earth long after you and I are gone.
For the record, the first sound we heard from a black hole was a B-flat. Computers identified it since human ears can't pinpoint a pitch that low: 57 octaves below middle C. Amazing.