Let said if there is a time travel machine, is it you can travel in time to be another person in the past? Or you will just like swimming back in a river? You see, unless there is a time recorder, otherwise if you travel back in time, whatever you have done are done. You won't be able to see it. Guess my question is complicated. Let's put in in this way, is it time is like a river, which when you swim harder, you can go in the reverse of the flow? Or is it you will go through some space to go back in time, and exist as another person on that time?