Robert Monroe travel outside of his body and then wrote about his experiences in a 3 book saga over his lifetime. In the second book he talked about projecting his consciousness into the future and he was "physically" prevented from getting close to a certain person by an invisible barrier. My speculation is that the other person was actually his consciousness in the future and the universe is already built to prevent those kinds of interactions, or maybe the impact we can have. But I guess that could also tie into the "we have no free will" theory. Maybe Steemit sc-fi writers could make it work lol