A shrunken, refrigerated balloon is expanding to normal size because a presenter blows hot air on it. Photo: Thomas Hjort Jensen

20th anniversary for explosions and wild colours

Wednesday 24 Nov 21


Maria Bundgaard
Personal Assistant & ScienceShow Manager
DTU Chemistry
+45 45 25 24 60

About DTU ScienceShow

Based on day-to-day life, DTU ScienceShow performs experiments that - in a clear and understandable way - explain some of the natural science phenomena that we experience every single day.

Source: DTU ScienceShow. Read more and book the show here.

Over the past 20 years, DTU ScienceShow has provided entertainment with fascinating experiments and brought science to thousands of people.

DTU ScienceShow does about 90 shows annually at libraries, schools, conferences, and DTU, where especially elementary school pupils and high school students can experience science experiments. Over the past five years alone, almost 52,000 people have watched the show. A figure that does not even include major festivals and Open Day events at DTU.

Mathilde Krogsgaard Vester — show presenter and MSC student — explains the idea behind DTU ScienceShow:

“If a flame suddenly changes colour to a sharp minty green, most people would like an explanation of what they’ve just seen,” she says, and elaborates:

“When we add copper chloride salt to the flame, the electrons in the salt are excited by the heat, causing a wild colour reaction as the electrons return to their ground state. This visual experiment is our tool for explaining to the audience that the electrons in the salt have undergone a quantum leap before their eyes and what it means more precisely for science and our everyday lives.”

Ved at tilføje et salt til en flamme fremkalder show-foreviserne et skarpt grønt lys, der minder om udstødningen på en raketmotor. Foto: DTU Kemi
By adding a salt to a flame, the show presenters produce a bright green light that resembles the exhaust from a rocket engine. Photo: DTU Chemistry

Chasing ‘Aha!’ reaction

The idea for DTU ScienceShow originated with Professor Kristian Speranza Mølhave from DTU Nanolab when he started his PhD at DTU in 2001.

“I helped start the physics show at Aarhus University and could see that DTU lacked a counterpart to this. I wanted to develop a concept in which several sciences were part of the show. That is not ‘just’ a physics or chemistry show,” he says and explains that the first period was spent calling schools, inserting ads in teacher magazines, and finding like-minded fellow students who wanted to ignite young people’s curiosity.

Based on day-to-day life, DTU ScienceShow was to show experiments that — in a clear and understandable way — could explain some of the natural science phenomena that we experience around us.

“The driving force has always been to chase the Aha! reaction. Especially among young people who sit at the very back of the classroom. When you see them react or become involved in a show, the show is a success,” he says, and points out that it is obviously also the intention that young people will become interested in studying engineering.

Explosions fascinate

One of the teachers who has repeatedly booked DTU ScienceShow to perform for his classes is Christian Dencker from Roskilde private Realskole. According to him, it is important that they focus a lot on the fascination value of their experiments.

“In the schools, we teach the models and laws of natural science, but it’s limited what we’re allowed to and can show our pupils in the classrooms. It’s therefore brilliant when DTU ScienceShow arrives with ‘old school’ explosions and reactions that catch the pupils' eyes and interest. In addition to the young people learning a lot during the show, I can also use their experiences as pegs to hang my teaching on,” says Christian Dencker.

He highlights an experiment with liquid nitrogen in a cola bottle as a sure hit that arouses the youngsters’ interest.

Nitrogen has a boiling point of approximately minus 200 degrees and expands 175 times in the process of converting from liquid to gas. This creates an enormous pressure in the closed cola bottle, which ends up exploding with a loud bang. 

Benjamin Bjørke — former show presenter and current consultant at the Danish Technological Institute — says that it is also one of the experiments he enjoyed the most when he was out performing.

“Even if the young people stop their ears, the explosion is surprisingly loud, and the experiment always manages to impress,” he says.

Flydende kvælstof i en lukket colaflaske skaber et højt brag i en tønde. Andre ting i tønden får en flyvetur. Foto: DTU Kemi
Liquid nitrogen in a closed cola bottle creates a loud explosion in a barrel. Other objects in the barrel are thrown into the air. Photo: DTU Chemistry


“Don't try this at home” is not enough

The safety aspect is a constant focus area of DTU ScienceShow, says Benjamin Bjørke.

The show is anchored at the Department of Chemistry and has an attached Advisory Board and an advisory group, which ensures that the actual experiments and the show presenters’ training comply with all DTU’s safety regulations.

“Safety and procedures have always been the object of great attention and dialogue. Therefore, peer training and ongoing training in the proper handling of chemicals are essential to sending out the students to perform the show safely,” says Benjamin Bjørke, who now works with chemical safety in the metallurgical laboratory at the Danish Technological Institute.

Kristian Speranza Mølhave — DTU ScienceShow founder and member of the advisory group — highlights another focus area as part of the safety assessment.

“It’s not enough simply to say “don't try this at home” and then otherwise just go for it. We have a huge responsibility to communicate the experiments properly and scientifically, and to select the right experiments.”

Kristian Speranza Mølhave is proud of the reach that the show has acquired, but hopes that the concept can develop into a kind of ScienceShow alarm centre:

“I imagine that—in principle—a teacher or a parent can pick up the phone and call our alarm centre to say: “here we think the natural science classes have become too boring”. We can then respond with a callout and give them a boost of inspiration. But with thousands of spectators every year, we’re already fulfilling that role in a way,” he says.  

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