I am in a rehearsal space in London’s Elephant and Castle watching four actors explain the mathematical significance of prime numbers through the medium of dance. They are telling the story of André Weil, a French Jew who in 1940 proved the Riemann hypothesis for curves. The scene changes to an argument about whether or not Weil might in fact be a Russian spy. “He said he’s a mathematician,” one character proffers. “That’s not a job,” another retorts. Marcus du Sautoy turns to me and whispers conspiratorially: “It is, actually.”
He should know. Professor of mathematics at New College, Oxford, Simonyi Professor for the Public Understanding of Science and author of several bestselling popular maths books (including The Music of the Primes, The Num8er My5teries and Around the World in 80 Games), Du Sautoy is the closest thing Britain has to a celebrity mathematician. He has spent his career attempting both to solve some of the discipline’s biggest questions and communicate the magic of mathematics to the world.
This play, which he is co-directing, is his latest venture in translating maths into art. The Axiom of Choice is described as “an exploration of free will, war and mathematics”; it is running in Oxford in November, before heading to India and then returning in 2025 for a UK tour. Weil, one of Du Sautoy’s mathematical heroes, proved his major theorem while in prison in France for disobeying the draft. Du Sautoy wrote the play in two months during lockdown, which he calls “a bit of an imprisonment for us all”. Mathematics, he muses, is “a very powerful place to escape to”.
Du Sautoy, 59, does not fit the stereotype of a maths professor. He loves playing the trumpet and tells me in passing he started learning Sanskrit during the pandemic to understand better the mind of Weil, who was obsessed with Hindu philosophy. In jeans and a black T-shirt bearing an infinity symbol, he bounces around the studio with as much energy as the actors.
“Maths and theatre actually have a lot in common,” he says: you create imaginary worlds then see where the rules you’ve constructed take you. This is far from his first theatre project – he has collaborated with the Barbican and the experimental theatre company Complicité on maths-related productions, and was the mathematical advisor on The Curious Incident of the Dog in the Night-Time at the National Theatre. He explains animatedly how episodes in Weil’s life map onto mathematical and philosophical concepts, such as when he is mistaken for a spy in Finland and about to be shot, saved only by a chance encounter. The play runs the scene twice, with two different outcomes that hinge on a butterfly brooch being dropped by accident – an allusion to chaos theory and the idea that weather patterns can be altered by a butterfly flapping its wings. Had Weil been executed in Finland, he never would have made his breakthroughs, which would impact all of us, as his work was foundational to particle physics and the cryptography used to protect systems such as air traffic control.
“What looks like totally abstract mathematics that shouldn’t have any application at all… they’re the things that are protecting us as we fly around the world,” Du Sautoy says. “We mustn’t forget that many of the applications we use in everyday life come from just pursuing mathematics for its own sake.”
Unfortunately, mathematics for its own sake is under threat. While adjacent subjects like computer science have been rising in popularity, the number of students starting maths degrees has been stagnating, with enrolments decreasing in particular at post-1992 institutions. Du Sautoy is a spokesperson for the Campaign for Mathematical Sciences (CaMS), which launched in 2021 when Leicester University closed its pure maths department. He is especially anxious about the impact fewer maths courses will have on the pipeline of maths teachers, who are increasingly unlikely to have a degree in the subject, especially in state schools. “Where are the maths teachers coming from?” he asks, adding that while he supported Rishi Sunak’s (now dropped) plan for maths in schools to 18, the teacher numbers just don’t add up.
In September, the government also scrapped plans for a £6m grant to establish a new National Academy for Mathematical Sciences. “This would be a crazy cut to make,” Du Sautoy warns. Mathematical sciences contributed to an estimated £495bn of the UK’s economic output last year. Politicians, he says, should fear the economic hit if the sector contracts. AI, data science, the algorithms used in everything from social media to computer animation – “If you let people cut out maths,” he says, “you’re not going to have the tools to be able to make the next big fundamental step.”
Du Sautoy sees mathematical patterns in everything: from the success of the band Radiohead (“Why is their music so amazing? It’s because they know how to use prime numbers!”) to tactics for Monopoly (always buy the orange properties; they’re the ones landed on most often). Surprisingly, he admits he found maths boring at school – at least until the age of 13, when his teacher (“a dour Scot, Mr Bailson”) asked to see him after class. “I thought I was in trouble,” he recalls. Instead, his teacher created for him “a mathematics course that I wish exists, a kind of literature of maths”, looking beyond the technical utility of algebra and geometry to the big ideas like fractals and infinity that reveal how the world works. “I owe that guy so much,” he says. “He was the person who said, you see that door over there? There’s an amazing secret garden behind there, and here’s the key to that garden.”
Everything he’s done since then – the books, the TV shows, the Royal Institution Christmas lectures aimed at children – is to try to share this key with the world and “pay back that mathematics teacher”.
“A mathematician is a storyteller – it’s just our stories are about numbers,” he tells me. Memorising equations should go hand in hand with learning what they can do: “Why aren’t we being told that sines and cosines are a telescope to understand the night sky?” he asks. I (vaguely) remember being taught to use sine and cosine to solve trigonometric equations, but I had no idea these functions were the basis for early astronomy.
I ask Du Sautoy about his own research. When he’s not writing books or collaborating on interdisciplinary projects with artists and musicians, he studies symmetry in more dimensions than the non-mathematician’s mind can comprehend. “Why is it useful? Frankly, I don’t care!” he laughs; he loves discovering new symmetries “just for the beauty of it”. But there are practical applications too, in encoding the data that gets sent through satellites in a way that can be corrected at the other end if it gets corrupted. We owe many of the images we have of other planets to “these very esoteric sophisticated symmetries”. Maths helping us understand the night sky, once again.
In a flash of satisfying symmetry, Du Sautoy’s work builds on the maths André Weil did in prison. As he says, it’s all interconnected – like Weil and chaos theory and the butterfly brooch. A small university maths department closes, and the teacher who might have inspired a future pupil to become a mathematician and make the next great breakthrough in pure maths – paving the way for leaps forward in AI, or space exploration, or nuclear fusion – never gets to exist. We think about maths all wrong, Du Sautoy tells me, before heading back to the rehearsal. It isn’t about doing sums or measuring triangles. “It’s a language that helps us read the universe.”
[See also: Ralph Nader: “The election is between the fascism of Trump and the autocracy of Harris”]
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This article appears in the 13 Nov 2024 issue of the New Statesman, Trump World