Humboldtians in private

Caution, Experiment!

By Heinz Oberhummer, recorded by Lilo Berg

Foto: Hubert Mican / ORF
Photo: Hubert Mican / ORF

Well, that’s a fine mess I’ve made. Even my redoubtable colleague Werner Gruber (on the right in the photo) has involuntarily taken a step back to avoid getting Diet Coke on his clothes – not something I have to worry about in my yellow coverall. We’re on stage at the Rabenhof Theatre in Vienna; our audience is yelling and clapping enthusiastically. And after an initial moment of shock, we two physicists are also pretty happy with the success of our experiment. I just dropped a few Mentos mints into the two large Diet Coke bottles, which promptly ejected torrents of brown liquid several metres into the air. There’s a scientific explanation for this effect, and when our third man, Martin Puntigam, appears on stage a moment later to quiz us, we’ll explain it all to him – and of course to our audience.

Werner Gruber is a physicist and, in his day job, the director of the Vienna Observatory. Martin Puntigam is a well-known Austrian cabaret artist. I’m a retired physics professor and together we’re the science cabaret act “Science Busters”. When we started out in 2007, we never imagined we’d be this successful. Today we have our own TV show with the Austrian state broadcaster ORF, our books and audiobooks are bestsellers and we frequently present our act in theatres. We cover topics such as brain research, climate change or extraterrestrial life, always focusing on making science entertaining and easy to under- stand. We want the audience to have fun – and we don’t mind if it’s sometimes at our expense.

“Those who know nothing must believe everything” – we’ve chosen this sentence by the wonderful Austrian writer Marie von Ebner- Eschenbach as our motto. We want to help our audiences overcome their unfounded fear of science and inspire them to think for themselves. For example when it comes to homoeopathy, which we consider a load of magical mumbo jumbo that we love to dissect. But there’s no wizardry to the Coke-Mentos experiment: when the mints are immersed in the beverage, they create vast amounts of foam that explodes upwards. It has nothing to do with the sugar in the sweets; the cause is the microscopic irregularities on their surface. These irregularities serve as nucleation sites for millions of carbon dioxide bubbles that are dissolved out from the fluid and shoot up. It’s pure physics, and also works with pumice instead of Mentos and champagne instead of coke. The experiment is child’s play – but we do recommend protective clothing.

published in Humboldt Kosmos 103/2014

Professor Dr Heinz Oberhummer was a Humboldt Research Fellow at the University of Tubingen in the 1980s and became professor emeritus at the Vienna University of Technology in 2007.