The dependence upon initial conditions of such a system means that it can be perturbed by the slightest degree in the beginning and be thrown completely out of an expected outcome. Allusions are made to the Butterfly Effect and turbulence, especially that characterized by the smoke rising from a lighted cigarette. All of this will no doubt seem dry and inexplicable to the average viewer, but the filmmakers understand it well. Julie's life echoes the problem of predicting weather studied by Edward Lorenz, then threatens to bifurcate and disappear into a Cantor dust. Even the careers of Julie's and Claire's husbands as policemen bring to mind the constraints inherent in a system which, however deterministic, cannot finally govern the outcome.
Lili Taylor was her usual fully animate and touching self as Julie, but I was more surprised by how well Courtney Love played the part of the loving friend who, in the end, can't follow Julie into her new world. Another watcher might see Julie as too self-centered, putting herself before her marriage and children, but I'm just selfish enough to say that she deserves to live at least as free as her husband and everyone outside the stilted realm of sports television, laundry, and dinners set for four. She has a right to pursue her dream, which has been suppressed by her husband. Moreover, as the chaos theme shows, once the threshold has been crossed, there is no return to 'normalcy'; either for waterfalls, curling smoke, or liberated housewives.