The Jagged, Monstrous Function That Broke Calculus
An editorially independent publication supported by the Simons Foundation.
Calculus is a powerful mathematical tool. But for hundreds of years after its invention in the 17th century, it stood on a shaky foundation. Its core concepts were rooted in intuition and informal arguments, rather than precise, formal definitions.
Two schools of thought emerged in response, according to Michael Barany, a historian of math and science at the University of Edinburgh. French mathematicians were by and large content to keep going. They were more concerned with applying calculus to problems in physics — using it to compute the trajectories of planets, for instance, or to study the behavior of electric currents. But by the 19th century, German mathematicians had begun to tear things down. They set out to find counterexamples that would undermine long-held assumptions, and eventually used those counterexamples to put calculus on more stable and durable footing.
One of these mathematicians was Karl Weierstrass. Though he showed an early aptitude for math, his father pressured him to study public finance and administration, with an eye toward joining the Prussian civil service. Bored with his university coursework, Weierstrass is said to have spent most of his time drinking and fencing; in the late 1830s, after failing to get his degree, he became a secondary school teacher, giving lessons in everything from math and physics to penmanship and gymnastics.
