Three masses pull on each other through gravity. Their motion has no closed-form solution — tiny changes in starting conditions explode into completely different futures. That's chaos.
F = G·m₁m₂/r². The system is integrated with a 4th-order Runge–Kutta scheme. For two bodies, orbits are perfect ellipses. Add a third and the equations become non-integrable: trajectories never repeat, never settle, and depend so sensitively on initial conditions that rounding errors at the 12th decimal place change the outcome within seconds. Hit Perturb & Compare — a ghost trail shows what happens if body 1 starts just 0.0001 units to the right. The two paths agree, then diverge wildly. That divergence rate is the system's Lyapunov exponent, and it's why long-term prediction is fundamentally impossible.