Period doubling and the route to chaos — a map of dynamical systems
The horizontal axis is the growth rate r. The vertical axis shows the long-term values of x after many iterations. One dot = stable fixed point. Two dots = period-2 cycle. The "dust" region = chaos (infinitely many values visited).
As r increases, stable behavior splits: 1 → 2 → 4 → 8 → 16... The gaps between bifurcations shrink by the Feigenbaum constant δ ≈ 4.669. This universal ratio appears in all systems with period-doubling routes to chaos!
Within the chaotic region, islands of stability appear. At r ≈ 3.83, a stable period-3 cycle emerges, then period-doubles itself! "Period 3 implies chaos" — Yorke & Li's famous theorem. Order and chaos interweave.
Zoom into any branch of the diagram and you'll find smaller copies of the whole. This fractal structure reveals deep connections between chaos and geometry. The bifurcation diagram is itself a kind of fractal!