There are several double pendulum videos on YouTube that demonstrate its chaotic motion, however only a few illustrate one key property of chaotic systems — very tiny differences in starting conditions can yield very large variations in the eventual path that the double pendulum follows. This is not true of a single pendulum. To illustrate this, I created a release mechanism to ensure that the double pendulum would always start in the same configuration and filmed multiple releases. Overlaying four trial runs in the same video reveals the very divergent paths followed by the same double pendulum in spite of starting from almost identical initial conditions. Very minor, near imperceptible deviations in the repeatability of the release mechanism were enough to cause this.

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