Peter Scholze, a German mathematician, created perfectoid spaces and was considered perhaps the greatest living mathematician at the time.

“This is not frontier math." And Kevin's like, "Okay, that's true. What is frontier math?" And in this period, uh, around 2018, frontier math is this object called perfectoid spaces, which is something that was created by a German mathematician named Peter Schulze, who is today and then as well considered maybe the greatest living mathematician.”