Suppose we have such a pair(A and B) and place detectors (not sure if more than one detector is possible or of use) along the path of particle A  but do not do so along the path of particle B   Is there any way to determine at which point (or between which points) particle B has any interaction?   Alternatively, is there any way at all it is possible to state  that there has not been any interaction (and so the particles are still entangled)?    As a related  (perha