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You cracked a puzzle about the structure of strange crystals called approximants that had gone unsolved for eight years. Tell us more.
Sven: Approximants are related to quasicrystals, which are ordered atomic structures, but with symmetries that were believed to be impossible, for example fivefold symmetry. The approximants we studied have fivefold and 10-fold symmetry.

The result was Linus’s name on a paper that was published in this month. What did you make of that?
Linus: It’s rare and strange and cool. I don’t know how many other 10-year-old kids have done this.

How did this father-son collaboration begin?
Linus: Me and my father did some sudoku. He was, like, “Let’s put this number here and this number here”, but I said that he was wrong. Then he was, like, “You’re better at puzzles than me”, and he asked if I wanted to help with this thing that he’d been working on for a few years. We sat down and found the solutions to some of these crystals.

Sven: We cracked it together. We cracked four structures out of six remaining. It was pretty much a 50/50 effort.

Are there similarities between solving sudoku puzzles and piecing together diffraction patterns and electron micrographs to solve approximant structures?
Sven: Quite a lot actually. Linus’s main contribution was coming at it with a clear mind, being smart and able to put the puzzle together. I sort of knew too many things, and when you try to do it yourself, your brain just gets exhausted by all the different things you keep in your head at the same time. With a fresh, empty brain, so to speak, you can do something. When solving problems, it is always good to have someone to discuss them with.

Linus: What we did was to solve a set of puzzles, where the pieces were “wheels” that could be connected in different ways.

Did it take long?
Linus: It took two days to find the solutions.

Linus is obviously exposed to a lot of science. Does a career in research beckon?
Sven: Because of our interest in quasicrystals, we had Daniel Shechtman [winner of the chemistry Nobel prize for discovering quasicrystals] here for dinner after he got his prize. He talked a little bit with Linus and said he could become an excellent scientist. But we are not pushing him, he can be what he wants.

Linus: I don’t know what I want to do yet.

When you’re not solving crystal structures, what do you like to do?
Linus: I like to play computer games with my friends. I have met a lot of people in different countries when playing games, for example Cyprus and Denmark. I also like to watch videos on Youtube.