nikola tesla said "if you want to find the secrets of the universe, think in terms of energy, frequency, and vibration."
the video below shows the "chladni plate experiment" which beautifully visualizes complex patterns that form as a result of resonant vibration on a solid surface. this experiment is achieved by connecting a metal plate to a speaker then, sprinkling sand on the plate's surface, change the pitch (frequency measured in Hertz (Hz)) of sound that vibrates the plate, and watch the sand jump into the resonance pattern that results from each different sound wave vibration.
the patterns are beautiful, and i particularly like the transitions between different frequencies. 5201 Hz is my favorite pattern!
this is what the chladni patterns for a square plate look like:
chladni first performed this experiment by running a violin-type bow along the side of the metal plate to find the resonance, so it shouldnt be as much of a fascinating surprise as i found it to be to see these patterns on a violin's surface!
a similar thing happens to guitars, mandolins, cellos, cymbals, etc. super cool.