although the time travel paradox explains natural boundries(fail safe mechanisms) it states you can't go back and kill yourself, but what stops somebody else from killing you? and further still can you only fail to kill someone in the past if you have that intention in mind? what about killing someone accidentally?. how can time or time travel read a persons intentions? I beleive it's possible to travel into someonele's future if your going at the speed of light because whilst what will actually be your present will be someones eventuall future because travelling at the speed of light slows your time down and they have already lived most of their life so effectively in earth terms you'll be the same age but have different physical and mental features. you still youthfull looking them grey and old)