Sale, un altoparlante ed una lastra di metallo.
I pattern che vedete apparire sono detti Pattern di Chadlni.
Ernest Florens Friedrich Chladni (1756 – 1827) performed many experiments to study the nodes of vibration of circular and square plates, generally fixed in the center and driven with a violin bow. The modes of vibration were identified by scattering salt or sand on the plate, these small particles end up in the places of zero vibration. Ernst Chladni first demonstrated this at the French Academy of Science in 1808, it caused such interest that the Emperor offered a kilogram of gold to the first person who could explain the patterns.
Magari un chilogrammo di polvere di oro, da usare al posto del sale.