August Kundt – a physicist – had an idea more than 150 years ago: He wanted to make invisible sound waves visible to us and thus show people that every sound is a vibration in the air. Therefore, he took a tube, filled it with cork dust and repeatedly sent sounds through it.

Look closely: Our experiment uses water instead of cork dust. Can you see how the sound has made a wave in the tube? A single sound has quite a lot of energy, right?