Picture of chalkboard with erased handwriting and desk with chair

The timeless beauty of a mathematician’s chalkboard

Mathematicians continue to calculate, solve, and create on chalkboards, even in the digital age. A photographer captures samples of their work.

Ideas explored on chalkboards—and erased and explored again and again—can lead to breakthroughs across disciplines, particularly in mathematics. At Princeton University, professor Noga Alon uses his board to study how graph theory can be applied to computer science, a relationship that has enabled modern advances in digital technology.

This story appears in the April 2021 issue of National Geographic magazine.

Detractors may deride mathematics as difficult, abstract, rigid, boring. But to admirers, mathematics is fascinating, creative, even an art form—and its canvases are chalkboards covered with scribbles, an odd mix of therapy and ingenuity known as board work.

Photographer Jessica Wynne learned about the beauty of mathematics from her summer neighbors on Cape Cod, Massachusetts. Both of them are theoretical mathematicians, and when their friends—also theoretical mathematicians—came over, Wynne noticed that chalkboard ponderings were how they communicated complex ideas and worked out knotty problems. They used chalkboards to collaborate and spar and, most of all, to explore the boundaries of known mathematics. Some described it as meditation.

At the Instituto Nacional de Matemática Pura e Aplicada in Rio de Janeiro, Brazil, Jacob Palis sees green at the chalkboard and out the classroom windows. A professor of mathematics, Palis does research in the areas of dynamical systems and ergodic theory.
At the Instituto Nacional de Matemática Pura e Aplicada in Rio de Janeiro, Brazil, Jacob Palis sees green at the chalkboard and out the classroom windows. A professor of mathematics, Palis does research in the areas of dynamical systems and ergodic theory.

In a world with plenty of paper, whiteboard, and digital screen space, why chalk? “That’s like asking a painter why they paint with oils,” says Wynne. But there are practical matters too, she says. Dry-erase markers stain clothes and hands. Then there’s how chalk sounds and feels when in use: a soft knock and rhythm, almost like a metronome. One University of Chicago mathematician vowed that if the math department replaced chalkboards with whiteboards, the faculty would revolt.

The quandaries of theoretical math are far more difficult than solving for x or balancing the quadratic equation. Some mathematicians try to find new universal truths, as Archimedes discovered pi and Pythagoras defined a right triangle. Board work also may be an end in itself—a place to record one’s thoughts, unrushed. Wynne photographed one heavily notated board, at Yale University, on which the professor had written in one corner: “Pls do not erase.” It had remained untouched for five years. 

A book of Wynne’s chalkboard images, Do Not Erase, is set for June 2021 publication by Princeton University Press.

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