In chaos theory, the butterfly effect is the sensitive dependence on initial conditions, where a small change at one place in a deterministic nonlinear system can result in large differences to a later state. The name of the effect, coined by Edward Lorenz, is derived from the theoretical example of a hurricane’s formation being contingent on whether or not a distant butterfly had flapped its wings several weeks before.
Although the butterfly effect may appear to be an esoteric and unlikely behavior, it is exhibited by very simple systems: for example, a ball placed at the crest of a hill may roll into any of several valleys depending on, among other things, slight differences in initial position.
The butterfly effect is a common trope in fiction when presenting scenarios involving time travel and with hypotheses where one storyline diverges at the moment of a seemingly minor event resulting in two significantly different outcomes.
You have noticed that everything an Indian does is in a circle,
and that is because the Power of the World always works in circles,
and everything and everything tries to be round.
In the old days all our power came to us from the sacred hoop
of the nation and so long as the hoop was unbroken the people
flourished. The flowering tree was the living center of the hoop,
and the circle of the four quarters nourished it. The east gave peace
and light, the south gave warmth, the west gave rain and the north
with its cold and mighty wind gave strength and endurance. This
knowledge came to us from the outer world with our religion.
Everything the power of the world does is done in a circle.
The sky is round and I have heard that the earth is round like a ball
and so are all the stars. The wind, in its greatest power, whirls.
Birds make their nests in circles, for theirs is the same religion as ours.
The sun comes forth and goes down again in a circle. The moon
does the same and both are round. Even the seasons form a great
circle in their changing and always come back again to where they were.
The life of a man is a circle from childhood to childhood, and so it is
in everything where power moves. Our teepees were round like the
nests of birds, and these were always set in a circle, the nation’s hoop,
a nest of many nests, where the Great Spirit meant for us to hatch our children.
Black Elk, Holy Man of the Oglala Sioux 1863-1950