Discussions about molecular science are not usually interrupted by shouts of "More beer for anyone?". But that is par for the course during this science festival with a difference in Hamburg. For the second year running, physicists, biologists, and chemists have swapped their labs and computers for the city's pubs to talk about physics, biology or astronomy with people there.

The Heisenberg Bar is one of 46 taking part in the 'Knowledge on tap' ('Wissen vom Fass') festival – and it is aptly named. Werner Heisenberg, born in Würzburg in 1901, was a pioneer of quantum physics. No better place, then, for a talk by Professor Bernhard Schmidt about the Large Hadron Collider and the science of small particles. He is a senior physicist at DESY in Hamburg, Germany's largest particle accelerator.

Electron models and beer mats

The bar is filled with people who sip their beers and ask occasional questions. Professor Schmidt has brought industrial magnets, hand-made models of electrons and oozes passion about his subject. Occasionally, a beer mat is used to illustrate the point that nothing can move faster than the speed of light.

It is a brilliant way to make science accessible. The festival slogan is "we quench your thirst for knowledge” and Professor Schmidt visibly enjoys doing so. "I am always amazed at the well-informed questions people ask from the floor," he says later. "This event breaks down the barriers between science and society. We need to bring science out of universities, out of laboratories, and into places like this."

Across the 46 venues there are talks on black holes, the science of coincidence, whether plants can feel pain, and how loud the big bang was. One, titled "Give peas a chance – the revival of legumes" explores whether beans, lupins and peas can help in the fight against cancer.

Popular science

It is popular science at its best and in the Heisenberg Bar it leads to a lively question and answer session about particle acceleration. Admittedly, the questions become a little more vague as the night goes on. At one stage an entire tray of beer also accelerates and is sadly lost, but no one seems to mind.

Carsten Koschmieder is one of those enjoying the talk with his beer. By day, he works with transformers. "I normally go to my own local pub," he says. "It's called the Big Bang. But tonight they had a talk about Madagascan snails there and that just wasn't my thing. I preferred the topic here because that's an area I'm interested in."

The bar owner, Andreas Deichert, has offered his pub to the festival both years running. "In Germany, too little is being done for education," he says. "Science does not reach the right places. Bars are great for this sort of thing because everyone meets there – from unemployed people to solicitors."

Science in unexpected places

Last year, 30 bars took part. This year's expansion came about because many who wanted to see the talks in 2015 were turned away. The idea of taking science out of scientific institutions and into the pub scene came from Israel, says Dr Thomas Zoufal from DESY, which organises the festival together with the University of Hamburg.

"The Weizmann Institute does something similar there and Professor Jan Louis from Hamburg University thought it was a fantastic concept. You need to catch people where they don't expect you and that way we may just be able to spark a passion for science in them.”

As the night draws to a close, it remains unclear whether the moderate consumption of alcoholic beverages actually aids our understanding of complex scientific concepts. The relaxed surroundings certainly do. But this is an experiment that looks set to continue.