Welcome to Quantum Magazine's podcasts.

Each episode, we bring you stories about developments in science and mathematics.

I'm Susan Vallett.

You're listening to the sound of metronomes.

If you place them side by side, they'll sway

in lockstep. During the summer, one cricket becomes what sounds like millions, chirping

together in unison. Neurons and our brains fire in synchronous patterns to operate our bodies

and minds.

Pace maker cells and our hearts sync up to generate the beat. These are just a few examples of how we live in a world of synchronization.

Now physicists have discovered new forms of synchronization,

and they're learning how to predict and control them.

Objects with rhythms naturally synchronize, but it was never documented until 1665, when Dutch

physicist and inventor Christian Higgins spent a few days sick in bed. Higgins had invented pendulum clocks, and two hung side by side on a wall near him.

He noticed that the pendulum swing exactly in unison, always swaying toward each other and then away.

He was curious as to why. Perhaps pressure from the air was synchronizing their

swings. What else could it be? He conducted experiments. Standing a table upright between the clocks

didn't affect their synchronization. But when he re-hung the clocks far apart or at right

angles to each other, they soon fell out of phase. Heiggins eventually

inferred that the clock's sympathy, as he called it, resulted from the kicks that their swings

gave each other through the wall. When the left pendulum swings left, it kicks the wall and the other

pendulum rightward, and vice versa. The clocks kick each other around until they kicks the wall and the other pendulum rightward, and vice versa.

The clocks kick each other around until they and the wall attain their most stable,

...