As an aside, since you actually seem interested and fairly comfortable with speculative physics, you may find this Everett FAQ quite fascinating. If not, that's OK too!
Not only am I prejudiced against wormholes, but I'm really prejudiced against the "many worlds" hypothesis (or more properly, wild conjecture). Anyway, let's give the causality thing a break for a while ... unless RadioAstronomer has a new viewpoint to contribute.