Agreed -- I used the word "fundamental" to suggest that it emerges from pure mathematics. In that sense, Feigenbaum's constants are in the same class as \pi and

Agreed -- I used the word "fundamental" to suggest that it emerges from pure mathematics. In that sense, Feigenbaum's constants are in the same class as \pi and e, which is distinct from the traditional "fundamental constants" of physics like c, \hbar, fundamental charge, etcetera. The fundamental constants of physics have, as yet, no known mathematical origin. Feigenbaum's constants, on the other hand, emerge from pure mathematics and also appear in nature. That they are expected to be irrational, like \pi and e, only adds to the charm.