This recording is a product of a glissando of sound waves that a team of MIT physicists sent through a carefully controlled gas of elementary particles known as fermions. The pitches that can be heard are the particular frequencies at which the gas resonates, like a plucked string. The way that sound travels through this fluid can be used to calculate the sound, and “quantum friction,” in neutron stars and other perfect fluids.

Read the related story: https://news.mit.edu/2020/sound-perfect-fluid-1203