The Physics of Music: Waves of Time and Rhythm

Time and rhythm are two elements that make up the very foundation of music itself. They are omnipresent and eternal elements that govern all movement in an orderly universe. The rhythmic motions of the heavenly bodies have been used for centuries to measure time, and in modern times, it is the rhythmic oscillations of the caesium-133 atom that do the job. And it turn, time governs the tempo (or speed) of rhythm; it can be safely said that one could not exist without the other, and music as we know it could not exist without them.

To understand the physics of rhythm, lets revisit frequency, the phenomenon that determines the pitch of a sound. Frequency is nothing more than the measurement of the number of repetitive movements (cycles) within a given time frame. Everything in the universe is cyclical, from the seasons on Earth to the predictable return of Haley's comet.

Everything that moves in waves does so in a rhythm. The wind-driven ripples across the tops of a vast wheat field, the endless waves of the seas that constantly lap at our shores, and, of course, sound itself, all have a rhythmic pattern to their natural cadences. Even the ultra-high frequency waves of the electro-magnetic spectrum (which gives us visible light, radio, and cosmic rays) pulse rhythmically through time and space.

Sound waves are mechanical waves, much slower than electro-magnetic waves, but are indeed the fastest of the mechanical waves. Even the lowest sub-sonic frequencies lie around 15 to 20 Hertz. So to examine rhythm, we must slow down the Pulse of the Universe even further; no longer can we measure things per second, but in minutes!

The Origins of Rhythm - Get very still and very quiet for a few seconds, if you will. Put your hand over your heart, feel, and listen to the natural cadence of your body pulsing your blood to everywhere it needs to go. Listen to the almost perfectly spaced "LUB-dub.....LUB-dub..." sounds of your heartbeat. One could very accurately guess that it is this natural biological rhythm that govern the first songs mankind had ever written!