So the main thing and again I'm not really equipped to explain the relativity behind this but I do think I understand it somewhat. The main thing in the situat

So the main thing and again I'm not really equipped to explain the relativity behind this but I do think I understand it somewhat. The main thing in the situation you're describing is that it's one way. Make it two way, imagine getting a message saying "don't send that message" from someone who has already seen the message you're about to send. You can imagine this and that's part of the problem understanding the issue I think. But if this combination of events was possible very many things that we know to be true about spacetime would have to not be true.