It began with a déjà vu: Rolf-Dieter Heuer started his anniversary lecture with the slide "In search of the blueprint of the universe". It was precisely this slide that had started everything back then, on 13 September 2007, at the Science Café. Fifteen years later, the former CERN Director General and Research Director for Particle Physics at DESY picked up on the big questions about the origin and structure of matter and spoke about the great progress that has been made in the meantime. The European research centre CERN, literally founded on the ruins of the Second World War in Europe to enable joint cutting-edge research across borders, played a decisive role in this progress.

The Science Café at DESY is a success story in its own right. The idea, which came from Waldemar Tausendfreund and Britta Liebaug, was simple: to offer particularly interested young people the opportunity to get in touch with scientists once a month in an informal atmosphere. The meeting place is the DESY bistro. The Science Café always begins with a lecture that explains a specific research topic in an exciting way. This is followed by a discussion round, the heart of the event, where guests can get up close to the researchers. The "Tausendfreund Rule" ensures that the young science fans are the main focus of attention, with questions being asked in order of age. The Science Café now has fans in all age groups.

In the 15 years of Science Café, we have discussed numerous science topics in this way: the really big questions about the universe, dark matter or black holes, for example. Just as exciting are current topics from research with photons or accelerator physics. But also everyday things led to interesting discussions in the Science Café – physics in Hollywood films, for example – or questions about possible energy sources of the future.

In the beginning, Waldemar Tausendfreund moderated the events, later Werner Brefeld, Bernhard Schmidt, and then I took over. The soul of the Science Café remains Britta Liebaug, who has come out of retirement to continue to take care of exciting lectures and speakers.

In 2020, the COVID pandemic forced us to hold the Science Café virtually. This change brought an unexpected advantage: we reached new fans through Zoom, participants from all over Germany, even people from abroad. That's why the Science Café now takes place as a hybrid event. The anniversary was the first event of this kind: with 50 participants live at DESY and dozens per livestream.

We are looking forward to all that is coming – and to all who will come to the Science Café. Our next event is on 25 January 2023 with Axel Lindner. The topic is "Axions – the holy grail of the largest and smallest?"

(Text: Karsten Büßer)