What is the Butterfly Effect?

Tricia Christensen
Tricia Christensen

The butterfly effect is a term used in chaos theory to describe how small changes to a seemingly unrelated thing or condition (also known as an initial condition) can affect large, complex systems. The term comes from the suggestion that the flapping of a butterfly's wings in South America could affect the weather in Texas, meaning that the tiniest influence on one part of a system can have a huge effect on another part. Taken more broadly, the butterfly effect is a way of describing how, unless all factors can be accounted for, large systems like the weather remain impossible to predict with total accuracy because there are too many unknown variables to track.

The "butterfly effect" concept holds that a seemingly insignificant action -- such as a butterfly flapping its wings -- can have a dramatic effect on a system -- such as weather.
The "butterfly effect" concept holds that a seemingly insignificant action -- such as a butterfly flapping its wings -- can have a dramatic effect on a system -- such as weather.

Origins in Weather Prediction

The concept of the butterfly effect is attributed to Edward Norton Lorenz, a mathematician and meteorologist, who was one of the first proponents of chaos theory. Lorenz was running global climate models on his computer one day and, hoping to save himself some time, ran one model from the middle rather than the beginning. The two weather predictions, one based on the entire process, including initial conditions, and another based on a portion of the data, starting with the process already part way completed, diverged drastically. Lorenz, along with most scientists of his time, had expected the computer models to be identical regardless of where they started. Instead, tiny, unpredictable variations caused the two models to differ.

Intrigued by the results, Lorenz began creating a mathematical explanation that would show the sensitive dependence of large, complex systems like the weather. Sensitive dependence means that the development of the system depends on a wide number of factors. To simplify his findings, Lorenz coined the butterfly explanation that has since become so widely known.

Other Systems

The butterfly effect applies to systems beyond weather; indeed, any complicated system may be vulnerable to seemingly small factors. For example, the travel of asteroids in the solar system can be difficult to predict. This is because the paths of asteroids can be affected by many different gravitational pulls throughout the solar system, including the gravity of the sun, of planets, of moons, and even other asteroids.

In human behavior, it may be possible for small initial changes to render behavior unpredictable. For example, the loved ones of someone who has committed suicide are often left wondering what could have caused the death. They might agonize over the myriad small details they did not see, but which could have predicted the suicide. The butterfly effect might suggest that a huge range of experiences, dispositions, and genetic, physical, and emotional factors were too many to account for in the person's actions.

Counter Theories

Since its development, a number of contradictory theories have been described in opposition to chaos theory and the butterfly effect. These argue that the large systems in question, while being immensely complex, still follow some sort of order, and therefore do not merit the descriptor "chaos." While the number of factors may be large, it is suggested, they are nevertheless quantifiable and finite.

Although the mathematical explanation that Lorenz developed might show the possible effects of a butterfly's wings on weather patterns, there is no evidence that actually proves it. Observation has shown that the effects of a butterfly's wings seems confined to a very small, localized area. Any large-scale effects seem to be dampened by the system at large.

Popular Culture

The concept of small variations producing widespread effects actually predates chaos theory. Writers like Ray Bradbury were particularly interested in the repercussions that might occur if a person traveled back in time and changed one small, insignificant detail. This concept has been the basis of numerous films and stories.

Tricia Christensen
Tricia Christensen

Tricia has a Literature degree from Sonoma State University and has been a frequent wiseGEEK contributor for many years. She is especially passionate about reading and writing, although her other interests include medicine, art, film, history, politics, ethics, and religion. Tricia lives in Northern California and is currently working on her first novel.

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Discussion Comments


Time may not exist. No one knows for sure.


Okay. I know that time doesn't really exist. Our clocks help us measure the rotations of the sun and the Earth. Just like tomorrow, in truth, today never ends. We experience light and darkness depending on the position of the sun to the Earth. But there is experience. What if we could re-live an event that we have already lived?

Time travel is so complex because you couldn't actually pick a certain day or place because you have no connection with that day or place except for yourself.


I totally believe in the butterfly effect as it relates to events in life. So many major things in my life would not have happened the way that they did if just one or two small details had been different.

We never know what sort of far-reaching effect our small, seemingly insignificant actions are having on other people's lives on a daily basis. There's really no way to make the right choice, because we have no way of knowing which way things will go when they appear to be unrelated.


While the infinity of a prolific metaphor is true, all true, the Butterfly effect and so many little things can change the world. how do we find our orchestra leader so we do this in ways that are for our better?


I've been a believer ever since 2007, and it's simply astonishing how you can explain everything in life according to this theory.


Post 5: That would be a paradox, I think, although it does sound similar.


post 6 has an error. As you reach the speed of light, you turn to energy. Nothing can go faster than the speed of light, which is also relative, so if you went at 3 x 10^8 m/s then to you, the speed of light is 3x 10^8 m/s.


This is a dumb subject. I should know. I am a physicist and time does not exist; it is a perception and based on the laws of the universe. Even if time was real, you could not travel backward because anything faster then light turns to energy.


I saw online where a scientist goes crazy, then goes back in time to kill himself. Is that considered a butterfly effect? I was wondering about that.


but Michael Crichton had already addressed the Chaos theory long before in the novel and later movie "Jurassic Park," and these later versions are variations. Really, in my thinking. i feel one ought to explore this route with a more scientific inclination. --Kyalo


Donnie Darko is another interesting film adaptation of the butterfly effect. The movie stars Jake Gyllenhaal as the title character and has reached a cult classic status since its original release in 2001. Donnie's sleepwalking causes change for those around him, thus proving that small occurrences can have massive influence. The movie is particularly popular for its odd plot twists and the inclusion of Donnie's imaginary six-foot rabbit, Frank.


Edward Norton Lorenz received various research awards and medals honoring his impressive body of work. In addition to being responsible for coining the "butterfly effect," Lornez served as professor emeritus at MIT from 1987 until his death in 2008.


The Ray Bradbury book that is talked about here is titled "A Sound of Thunder", there was also a movie made from it of the same title. Personally I think they better portray the butterfly effect than the Ashton Kutcher movie (Butterfly Effect)does.

The Butterfly Effect movie holds that the main character is able to manipulate his reality in "real-time" by reading his diary of past events. It isn't really about the butterfly effect in relation to Chaos Theory. But as mentioned, it certainly makes the range of possible negative effects hit home.

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