Black holes and sound waves.

[yewtree]

Did you know..



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

[rachmaninoff_forever]

At what point would you consider that a rhythm then?

Cause the low A on the piano is 27hz I think.

But 57 octaves below middle c???  We would just hear that as a rhythm

[georgey]

Trying to do the math here with a quick spreadsheet.  60*60*24*365 = 31,536,000 seconds in a year.
Middle C is about 261 Hz.  The means a string on the piano would vibrate 261 times per second with middle C
1 octave below middle C would vibrate about 130 times per second.
2 octaves below middle C would vibrate about 65 times per second.
8 octaves below middle C would vibrate about 1 times per second.
57 octaves below would vibrate once every 17.5 million years if I did the math right. 

[georgey]

Maybe a physics person can do the calculation.  My crazy wild guess might be something like:

Take a string that is 100 million miles thick made up of some kind of material and stretch it between 2 points that are a light year apart and give it the proper tension to tune it to 57 octaves below middle c.  Give it a pluck (or hit it hard enough) and you will get your low note.  

[Bob]

I vaguely remember seeing an article mentioning the Hz where people could hear either the pitch or individual clicks.  I think it was 14Hz.  General human hearing is 20-20,000Hz, so that's making sense.  I can't find anything on it now.


Kind of sounds like music of the spheres information.

[piulento]

To anyone wondering how this happens - the heat emitted from the black hole's accretion disc creates small periodic oscillations in the density of the gas clouds around it, which spread outwards, sort of like sound waves that spread through the air.
I wouldn't really call it a note at this point, or even sound for that matter. It's more like a repeating disturbance in a gas cloud.