Introduction: (can be skipped) We know the problems around the collapse of the state (specially that we don't know how an outcome is selected from the preferred states). Now thousand of experiments shows us that this strange not unitary transformation of the states occurs when a measurement is made. Also Quantum mechanics is not local and there are many experiments of quantum entanglement that can argued in favor of this strange behavior (there is a debate about the validity of this experiments). The paradox between the intrinsic local nature of special relativity and the non-local nature of quantum mechanics is solved because a measurement will destroy the state. This mean that if a guy measure one of the entangle particle he will force the state of the other particle (we are assuming a collapse again) to some state, but the guy that have the other particle have no means to know in which state is his particle, then he will ignored the fact that the other particle was measured. No transfer the information, then no contradiction with special relativity. Now to the key point of this post. (paradox) Suppose that both entangled particles are measured and the differences between this events is spacelike. That mean that for some inertia frame both measurement were made a the same time. My question is which one of the measurement produce the collapse of the state? A person can answer that both measurement produced the collapse. That is wrong because in another inertia frame we can see that a measurement was made before the other and by conventional quantum mechanics was this measurement the one that produced the collapse. But in another inertia frame the order of the measurement is the other way around then the other measurement was the one that produced the collapse. The result of the experiment is the same and not information could be transferred, then in this sense there is not a violation to causality, except for the collapse. If we related the collapse as a effect of the measurement, then there is a problem here, causality is violated. I think that the reason of this paradox is that the collapse is not well defined. The paradox is that the collapse was produced by different measurements depending of the inertia reference frame, then we expect from a relation of cause and effect that the order of the events should be invariant, this is not the case. Then how can we said that the measurement cause a collapse? I hope to see some replies.