What is the butterfly effect?
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Taken from meteorology, the idea that a small change (like the flapping of butterfly wings) can cause a big impact somewhere else eg storm over California.
The idea comes from the study of chaotic systems. A chaotic system is one which can in concept be predicted (provided its initial state is known) but which is highly sensitive to initial conditions, producing very different results from slight changes to its initial state. Think about rolling a rock down a hill, a very minor change to which way it tips initially can lead to the rock coming to rest in a completely different spot. Even if you tried to roll the same rock in exactly the same way an invisibly small variation can lead to it glancing off a lump in the ground and taking a completely different path than before.
This aspect of chaotic systems is what is referred to with the “Butterfly Effect”, which is the idea that something as tiny as the flapping of a butterfly can influence the world such that the future turns out completely differently. The flapping is that tiny, seemingly inconsequential change which would result in the chaotic system turning out completely different.
A small events can bubble up into big effects which is why predicting things is hard without knowing every piece of data (which is impossible).
Give the lyrics to 99 luftballoons a read. Starts with some kids playing with red balloons and ends in a nuclear holocaust all with an upbeat tune.
It’s basically a description of chaos theory.
Chaos theory is a description of chaotic systems. A chaotic system is a system where every single action is deterministic based on the initial conditions, but if we even slightly change the initial conditions, the outcome is wildly different.
Basically, weather is a chaotic system. Let’s say we accounted for every possible variable in the weather but one butterfly. That means we know exactly how the weather is supposed to behave throughout all of time in a world where that butterfly doesn’t exist. And let’s assume that prediction says there’s supposed to be clear weather in Kanas in the next 3 days. Well if that butterfly flaps it’s wings, it just changed the conditions that we measured. Now the entire outcome is now completely different and now 3 days later there’s a tornado in Kansas.
A double pendulum is a very simple example of a chaotic system. If you watch some videos of that, you will see that they look as if they start from the same position, but slight variations in that starting position completely changes the path the pendulum takes.
The butterfly effect is a story told to make the point that small changes can *sometimes* have large effects. The story is that if a butterfly flaps its wings in the Amazon rain forest, it can alter the course of a typhoon half a world away.
That’s an exaggeration, and is made worse when people further exaggerate the story and say a butterfly can start a typhoon all by itself. A more realistic example is that small changes in Earth’s orbit can and do cause big changes in Earth’s weather.
But it’s just as likely that small changes will have *no* discernible effect, and there’s no way of predicting which changes will matter. Sometimes, to paraphrase Ben Franklin, for want of a nail a kingdom is lost — but much more often the lack of a nail has a negligible effect on the kingdom, as one would expect.
The story of the butterfly effect was originally used by a meteorologist, Edward Lorenz (1917–2008). Lorenz used the story to make the point that it’s impossible to perfectly predict the weather because it’s impossible to know all the necessary variables. Weather is so complex that small variables can — sometimes — change the direction of a typhoon.
But Lorenz always stressed that there’s also no way of knowing *which* small variable results in a big change. Thus we can’t harness the power of butterflies to change the direction of typhoons and hurricanes. The butterfly was just an example of a small variable, but there are innumerable small variables and we can’t tell ahead of time which ones will matter.
The butterfly effect is also invoked in fictional time travel stories, where time travelers change the past in a small way and cause a large change when the return to the future. Time travel into the past is, of course, impossible. The stories also exaggerate the effect by making it seem certain that *any* small change will result in a wildly different future, whereas it’s more likely that the nearly all small changes won’t have a noticeable effect — although it is true that some might.
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