A Butterfly in Brazil

Dozens of scientists were on the edge of their seats. Hundreds of eager onlookers from the general public listened intently to every word flowing from Edward Lorenz.

The American Association for the Advancement of Science (AAAS) had booked its annual meeting in DC for 1972. There was always plenty of enthusiasm from meteorologists, mathematicians, physicists, and experts in other fields, but this year’s talk on chaos theory, a newly budding field, attracted a more sensational and diverse group than usual.

Lorenz began to describe how an action as simple as a butterfly flapping its wings in the Amazon rainforest in Brazil could cause a tornado in Texas. In fact, this was the centerpiece of the title of the lecture:

"Predictability: Does the Flap of a Butterfly's Wings in Brazil Set off a Tornado in Texas?"

Like a lot of stunning discoveries and sensational ideas, chaos theory came about because of meticulous work. While studying weather models on early computers in the 1960s, Edward Lorenz was using simplified mathematical models to simulate weather patterns. This is no wonder, since saving computing time was incredibly important.

In doing so, Lorenz rounded off some initial conditions to the nearest hundredth. This turned out to be no good at all, wrecking his attempt at running the calculation.

Then, he ran the same simulation twice, starting with both the rounded and exact initial conditions. Unexpectedly, the simulations diverged wildly after a short time, leading to significantly different weather outcomes within just a few days.

Initially skeptical, Lorenz repeated the experiment, confirming the drastic divergence even with tiny initial differences. He realized this sensitivity to initial conditions was inherent in chaotic systems like weather, making long-term predictions practically impossible.

Portrait of Edward Lorenz, courtesy of Organ Museum

Why was this such a big deal?

Well, for starters, it allowed folks to think outside of the box, to leave the doorway to the absurd slightly ajar. Lorenz gave folks the ability to visualize what his experiment represented: that tiny variations could compound into mind-blowingly huge outcomes.

Envision that butterfly in Brazil with me. It takes flight in an unexpected direction, possibly avoiding a predator, or maybe just deciding to move to a different spot.

Flapping of its wings creates a tiny swirl of air, moving trillions of molecules around like an invisible baby hurricane in the air. The delicate breeze generated by the butterfly might slightly alter the path of a pollen grain, which in turn disturbs the flight path of another insect.

Now, the insect pollinates a flower it would have otherwise missed, tipping the balance in favor of a bird visiting that flower. Instead of a butterfly, we’re now discussing a more powerful, larger effect on the surrounding area: the movement of a bird.

Each of these small events, in turn, creates its own set of ripples through the ecosystem.

If other birds follow suit and start moving pollen around, it’s easy to imagine how this subtle change in the ecosystem could slightly alter the humidity or temperature in a small area. These variations can escalate over time and distance, eventually coming to influence weather patterns far removed from the butterfly's original location.

Weeks later, these accumulated atmospheric changes might contribute to the formation of a storm system in Texas.

The realization that small variations can lead to unpredictable outcomes led to major advances in fields way outside of meteorology. Economists began to reevaluate models of market behavior, and medical researchers developed a better understanding of the dynamics of human physiology and disease progression. After all, the human body is a very complex system.

In popular culture, the Butterfly Effect has transcended its scientific origins to become a metaphor for the interconnectedness and unpredictability of life. We use the phrase commonly to convey the idea that a small personal choice can have far-reaching consequences, both good and bad.

Think back on your own life. Have there been some small “butterfly flaps”, where you’ve done some kind of seemingly small action, only to discover far-reaching implications down the line?