Time travel, if possible, can ONLY have you going into the future, as the past already exists.
You CAN'T go back and kill Hitler, because you were born in 1967.
Kill Hitler, time changes, your parents meet or don't, you can't possibly have been conceived so you can go back in time.
Fun to think about, though.
There’s another reason Time Travel is impractical, as well.
Remember the old physics law that says, “Matter and energy can neither be destroyed nor created, outside of nuclear reaction, it just changes form.”
There is a finite amount of matter and energy in this universe.
If you leave this time and travel, forward or backward in it, you would be ‘creating’ more matter than the universe had in it at that time. All matter in you and your machine was here, in some oth. form, at the time you chose to visit. The same matter cannot be in two places at the same time. Every atom and erg of energy must balance out and be accounted for.
So, in order to travel in Space-Time, you would have to transfer the exact same amount of matter and energy to the place you left, and vice versa when you come back, if possible.......