Cosmic B♭

The lowest note in the known universe is caused by the rumbling of a black hole in the Perseus galaxy – 57 octaves below middle C.

— UberFacts (@UberFacts) February 20, 2014

I read this on Twitter this morning.

I think it’s a bit hard to justify this as a sound, for two reasons. Firstly, a frequency of 57 octaves below middle C would be far to low for the human ear to detect – a single oscillation of takes about 9.5 million years. Secondly, in the vacuum of deep space there would be no medium for the sound to propagate through, again meaning we wouldn’t be able hear it.

Even so, that’s very low! It’s caused by the inflation of bubbles of plasma in the centre of the Perseus galaxy cluster and oscillates at the frequency of a B♭. The note was discovered by Cambridge University professors in 2003 using the Chandra X-ray Observatory. I think that’s quite interesting!