The bifurcation diagram was not created by Mitchell Feigenbaum, but he found a way to understand it that no one had thought of. Among other things, the bifurcation diagram represents an idealized version of how a system can become chaotic. As you can see from the diagram below, the diagram splits into two after a certain point (a bifurcation) and into four at a later point. The bifurcations come faster and faster until the system becomes chaotic. Feigenbaum discovered that the bifurcations were occurring at a ratio that approached an irrational number that is approximately 4.669 in the bifurcation diagram. This was found to be true by experiment in real life examples. 4.669 is a universal constant in much the same way 3.14 is. Feigenbaum's bifurcation diagram is often called the fig tree because Feigenbaum means fig tree in German (also the bifurcation diagram looks somewhat like a sideways tree).