No. 55 · Risk · Physics
Butterfly Effect
In a complex system, a tiny change at the start can grow into a huge difference at the end.
In the Almanac
“Lorenz’s rounded number”, 1961 · “Fastly”, 2021
Both stories in full, three ways to use it and where it misleads.
Get the AlmanacQuestions
What is Butterfly Effect?
The Butterfly Effect is the idea that in complex systems, very small changes at the start can grow into enormous differences later. It's why long-range weather forecasts break down.
How do you use Butterfly Effect?
Use it two ways. Stay humble about long-term predictions and write your plans in pencil. And respect small actions: a slightly earlier alarm, a brief thank-you or a careful word can compound into outcomes far larger than they first appear.
When does Butterfly Effect matter?
Butterfly Effect is one of the 32 mental models for risk, the situations where you ask: What could go wrong, and what will I do if it does? Within that, it belongs to “The unexpected”, alongside Black Swan Event, Boiling Frog and Chaos Theory.
What is an example of Butterfly Effect?
Two stories show it at work: Lorenz’s rounded number (1961) and Fastly (2021). Both are told in full in The Mental Models Daily Almanac, which has two stories for each of its 365 models.
Which mental models are related to Butterfly Effect?
Chaos Theory, Compounding Effect and Unknown Unknowns. Butterfly Effect itself comes from physics.