Born in 1995, Stefan gained a master’s degree in philosophy in Leiden at the age of eighteen, after which he moved from Sweden to work on a PhD. Within eighteen months (instead of the usual four years) he gained his doctorate, making him one of the youngest ever PhDs. He is currently studying the philosophy of mathematics as a post-doctoral researcher. Along with Govrien Oldenburger he is the author of a children’s book The Kingdom of Sums (2018). He lives in Amsterdam.