If you’ve ever had the chance to see one in physics class, you may have come across a Ruben’s Tube when learning about acoustic standing waves. For those who haven’t (or need a quick brush-up), a Ruben’s Tube is a hole-riddled hollow tube filled with flammable gas; it shows how normally invisible sound waves and pressure interact in the physical world (and also allows for some spectacular on-the-spot cooking shows).
Nowadays, the apparatus isn’t used as much apart from the occasional school presentation, but the Fysikshow team of chemists and physicists from Denmark are bringing the Ruben’s Tube back into the spotlight:
The team’s ‘Pyro Board’ is made up of 2,500 holes and is connected to a sound processor that pumps sound waves through the holed board—effectively making each flame from each of the 2,500 holes dance to the beat of the music.
At the lowest frequency using a standing wave, the Pyro Board delivers a steady flame throughout all the holes. Increasing the volume increases the intensity of each flame, but for the most part, all the holes still operate on the same frequency. At high volumes, the maximum sound amplitudes (antinodes) become the areas with the most flame while the minimum sound amplitudes (nodes) produce less flame.
Where it gets fascinating, however, is when a multi-textured beat is passed through. Since a multi-textured track has a ton of notes and bass fluctuations, the flames move in rhythm with the music. Subtle notes, such as treble chirps within the track make the flames dance— while deep bass notes increase the flame intensity in the center.
Ultimately, as the music and tracks change, so too does the behavior of the flames. While seeing this Pyro Board at any nightclub would undoubtedly make for an entertaining night, the guys at Fysikshow are content to show the wonders of physics and the Ruben’s Tube to lucky kids in schools across Denmark. Possible Kickstarter campaign in the not-too-distant future, fellas?