Musica universalis

 Music of the spheres lives whenever black holes merge, proving Einstein to be right yet again.

When two black holes slam together, they don’t make a sound. And yet, this is what we hear if we listen closely.

[CLIP: Black hole “chirp”]

Let’s listen again. 

[CLIP: Black hole “chirp”]

That “chirp” is what we heard from two black holes that slammed together about a billion light-years from Earth. The tone rises as they spiral closer together, and abruptly stops when they merge.

But sound can’t travel through the vacuum of space. So what exactly are we hearing?

Each of these black holes weighs as much as several stars; hefty enough that as they pass through space they make waves— gravitational waves, specifically.   

These waves are undulations in the fabric of spacetime that fan outwards at the speed of light, like ripples on a cosmic pond. 

Albert Einstein predicted this phenomenon in 1916, based on his theory of general relativity, but was skeptical that gravitational waves could ever be detected.

Even the strong ones from colliding black holes produce ripples roughly a thousandth the size of a proton.

It took almost a century for scientists to prove him wrong. 

Harmony of the World from Ebenezer Sibly's Astrology (1806)

The musica universalis (literally universal music), also called music of the spheres or harmony of the spheres, is a philosophical concept that regards proportions in the movements of celestial bodies – the Sun, Moon, and planets – as a form of music. The theory, originating in ancient Greece, was a tenet of Pythagoreanism, and was later developed by 16th-century astronomer Johannes Kepler.