There is not a day that goes by when Heiner Claessen does not deal with languages. He picks up a dictionary and explores new ones. Currently, he speaks Japanese and Welsh, the last European language he has lost. But the mathematician prefers to log on to the Hypia portal, a platform for people who want to exchange ideas in different languages. “I prefer to choose something exotic and choose a partner who suits them,” says the 44-year-old. “Conversing in Lithuanian, Latvian, Hungarian, Finnish and Icelandic is a great pleasure for me. Unfortunately, I do not come across these languages very often in everyday life.”