Two metronomes began ticking at different times. They sat on the same movable platform, each keeping its own beat. Gradually, their rhythms came together. No one adjusted them. The connection beneath them was enough.
When I photographed Steven Strogatz at Cornell in November 2025, he demonstrated this small experiment with obvious pleasure. We worked in his office at Malott Hall and later in the Space Sciences Building. He seemed to enjoy watching the metronomes as much as explaining them. I liked that about him. Here was something he understood deeply, and it could still delight him.
As each metronome swings, it gives the platform a small push. That movement nudges the other metronome in turn. Over time, these small adjustments can bring their rhythms together.
Steven has spent much of his career studying how this happens. Fireflies can coordinate their flashes. Cells in the heart produce a regular beat. In each case, individual parts influence one another until a shared rhythm emerges. The mathematics helps explain when that coordination will develop and when it will break down.
No single part needs to know what all the others are doing. A firefly responds to nearby flashes. A metronome responds to movement beneath it. From these limited exchanges, something larger takes shape.
In the 1990s, Steven and his graduate student Duncan Watts began investigating how the arrangement of connections affects a system’s behavior. Their work led to a paper published in 1998 that helped establish the modern study of networks.
Think about a circle of friends. Many know one another, and their acquaintances overlap. Someone in that circle also knows a person in another city, who belongs to an entirely different group. A few such connections can dramatically shorten the distance between people who otherwise seem far apart.
Watts and Strogatz showed mathematically how a network could preserve close local groups while gaining short routes across the whole system. They found similar patterns among actors connected through films, in an electrical power grid, and in the nervous system of a worm. A few connections reaching beyond the local group could make the whole network surprisingly small.
Steven has a gift for making ideas like these approachable. He is warm and funny, and he listens carefully. You feel that a question is welcome, including one you might hesitate to ask someone else. He can give you enough of an idea to begin thinking with it yourself.
His books extend that invitation. In Sync, he explores how order arises among interacting parts. The Joy of x takes familiar experiences as starting points for mathematics. In Infinite Powers, he explains how calculus gave us ways to understand continuous change. He writes for people who may have decided years ago that mathematics was closed to them.
During our time together, he gave a simple demonstration the attention it deserved. There was time to watch, to wonder what was happening, and then to understand a little of it.
I could follow the movement of either metronome. The surprise was what happened between them. Watching with Steven, I began to understand why a mathematician might spend a lifetime studying the connection.
