UW Rainwater Seminar
Autumn, 2003



Speaker: Albert M. Fisher, University of Sao Paulo

Title: Fractals, Flows, and Randomness

Date: September 9 at 2:30pm

Location: UW Padelford C-401

Abstract:

We study fractal-like geometric objects by means of the flow defined by zooming toward a point of an ambient Euclidean space. This ``scenery flow'' provides an analogue for the geodesic flow associated to a Kleinian group. One consequence is a dimension formula for Julia sets which unites and simplifies the Sullivan and Bowen-Ruelle formulas to: Hausdorff dimension equals scenery flow entropy. For fractal sets, the translation scenery flow has a natural conservative ergodic infinite measure. This observation builds a bridge between fractal geometry and the probability theory of recurrent events, suggesting on the one hand new theorems for the Fuchsian case and on ther other a new interpretation of some results on countable state Markov chains due to Feller and Chung-Erd\"os. Interesting examples are seen in the intermittent return-time behavior of maps of the interval with an indifferent fixed point.