2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/89223Contrary to the opinion of J. Polchinski [Phys.Rev.Lett. {\bf 66}, 397-400 (1991)], the phenomenon of superluminal messages in nonlinear versions of quantum mechanics is not a specific difficulty in a class of theories formulated by S. Weinberg [Ann.Phys. (N.Y.), {\bf 194}, 336-386 (1989)]. It appears in all schemes which try to enlarge the orthodox class of observables, while conserving the traditional structure of the pure and mixed states.style changes, one reference addedQuantum PhysicsHigh Energy Physics - Theorytext