A wave is a disturbance. It is an interruption of space. So everything is just perfect until you get an idea that competes with the pre-existing emptiness for your attention. And this disturbance propagates through space, often transferring energy.
Video clips from the "golden age" of Mexican popular music: boleros, rancheras, huapangos and rumbas from artists who were popular from the '20s through the '50s.