The musical note that can trigger cold sweats and sightings of the dead

Imagine that all the frequencies nature affords were laid out on an extended piano keyboard. Never mind that some waves are mechanical, propagated through air or some other fluid, and other waves are electro-magnetic and can pass through a vacuum. Lay them down together, and what do you get?

The startling answer is a surprisingly narrow piano. To play X-rays (whose waves cycle up to 30,000,000,000,000,000,000 times per second), our pianist would have to travel a mere nine metres to the right of middle C. Wandering nine and a half metres in the other direction, our pianist would then be able to sound the super-bass note generated by shockwaves rippling through the hot gas around a supermassive black hole in the Perseus cluster – a wave that cycles just once every 18.5 million years.

Closer to home, how big do you think that piano would have to be for it to play every note distinguishable by the human ear? You’d have to add barely a single octave to either side of a regular concert grand.