Take a subwoofer of a computer speaker system and glue a petridish to the subwoofer cone. Pour some silicone oil (20cSt) into the petridish and vibrate it vertically by driving the speaker with a sinusoidal audio signal composed of 80Hz and 40Hz along with a phase difference. Flick a toothpick or use a syringe to create millitmeter-sized droplets on the free surface of the liquid that will start walking horizontally. These are superwalking droplets that constitute self-propelled classical wave-particle entities. Such wave-particle entities can exhibit hydrodynamic quantum analogs whilst also forming a fascinating active-matter system, but above all, observing their motion and interactions is mesmerizing.
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