2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/227951We show that if M is a hyperbolic 3-manifold which admits a quasigeodesic flow, then pi_1(M) acts faithfully on a universal circle by homeomorphisms, and preserves a pair of invariant laminations of this circle. As a corollary, we show that the Thurston norm can be characterized by quasigeodesic flows, thereby generalizing a theorem of Mosher, and we give the first example of a closed hyperbolic 3-manifold without a quasigeodesic flow, answering a long-standing question of Thurston.This is the version published by Geometry & Topology on 29 November 2006. V4: typsetting correctionsGeometric TopologyDynamical Systems57R30, 37C10, 37D40, 53C23, 57M50text