Finite-scale geometric invariants for chaotic and weakly chaotic dynamics

Abstract

We introduce a finite scale geometric observable that quantifies the growth rate of localized sets under time evolution in dissipative dynamical systems. Defined at finite time and resolution without reference to symbolic dynamics or Markov partitions this observable converges, in uniformly hyperbolic systems, to a resolution dependent plateau whose logarithmic scaling coefficient equals the Kolmogorov Sinai entropy. In merely hyperbolic systems, it decays to zero, reflecting the absence of entropy production, while remaining well defined at finite scales. Numerical results for the Henon map and Feigenbaum point illustrate these behaviors. Our findings yield a finite scale geometric characterization of chaotic dynamics, consistent with classical entropy theory where applicable. We further demonstrate that the observable remains well defined in open intermittent systems, where trajectories escape and classical asymptotic invariants fail, revealing finite scale signatures of transient weak chaos.