As many, I wondered why FTL communication has problems with causality. Went over many posts here in PF, and wasn't satisfied. And then I read this explanation, by Richard Baker: (2015-4-2, link is still active) http://www.theculture.org/rich/sharpblue/archives/000089.html His explanation is a bit more clear, but there's something I still don't understand: 1) Alice is positioned at P, and sends an FTL massage (for example "Hi Bob, planet Zoton is right in front of me") to Bob, who is positioned at Q. 2) Bob transmits an answer ("OK, now push the red button") to Carol, who is also at Q (what's carol's use in the explanation, by the way? Didn't get it), and Carol transmits the answer to Dave at position R. 3) Dave then transmits the answer to Alice... who is also at position R??? How can she be at P and R at (almost) the same time? Didn't she just transmitted the instantaneous FTL massage 10 seconds ago from position P? Is it the same Alice at all? If not, when did she get replicated? Or... Are Dave and Carol even in the same universe as Alice and Bob? WHAT'S GOING ON???