Ada Palmer

This is what scientists call sensitive dependence on initial conditions, more popularly known as the butterfly effect.

A small perturbation, the flutter of a butterfly's wings, the assassination of a prince, can cascade into enormous consequences through chains of causation impossible to foresee.

Stand beside a river and watch the water flow.

In some stretches it moves smoothly.

Cast a twig into the flow and it drifts peacefully downstream.

The water follows predictable patterns.

This is what physicists call laminar flow.

It's orderly and stable and small disturbances quickly dissipate.

But look downstream where the river narrows to meet rocks.

The water churns and froths.

Whirlpools form and dissolve.

Sometimes you feel like you recognize a pattern but no two whirlpools are ever exactly the same.

Drop a twig at this place and you cannot predict where it ends.

It might circle three times and shoot left or catch an eddy and spiral right or get pulled under and pop up 20 feet downstream.

Small differences in exactly where and how it enters produce completely different paths.

This is turbulence.

And this is what chaos theory studies.

It looks at turbulent system and asks, what exactly can we say about it?

What predictions are possible when prediction seems impossible?

And given that history flows very much like a river, with political science studying its laminar aspect and Palmer students learning to navigate the turbulent moments, what can chaos theory teach us about history?