In June this year, a global survey found that only 59 percent of people in Western Europe believe vaccines are safe. The most powerful leader in the world thinks climate change is a hoax. We seem to be living in a post-truth world, where experts are derided and science has become just another point of view. So how do you promote science and common sense under these conditions? Well, the Big Challenge Science Festival in the Norwegian city of Trondheim focuses precisely on this issue. From there, I made this report for Deutsche Welle’s Spectrum programme.