How the 18th-century steam engine helped physicists make a quantum breakthrough

The hissing sound you hear in the background when you turn up the volume of your music player is called "noise". Most of this hiss is due to the thermal motion of electrons in the music-player circuitry. Just like molecules in a hot gas, electrons in the circuitry are constantly jiggling about in a random fashion, and this motion this gives rise to an unwanted noise signal.