I figured out why time travel to the past with the idea of changing things to affect the present is not possibleYou can go back in time but if you did there would be nothing there. Imagine if time were like riding in a car with friends the car is the universe, if you personally went back to a place where you had been previously you would be there alone, without the car, without the rest of the universe standing alone in the road.

The atoms that make everything up exist through time, if you went back in time and didn't take all the atoms on earth with you you would be alone in time without any ability to affect the atoms which exist in another time period.

This is why you can go forward in time but not backward, you could get out of your car that is the universe and if you could go faster than the car you could stand alone in the road and wait for the car to catch up with you. This is what going near light speed does, slows you to go faster through time than the rest of the universe and then it catches up to you in the future

but you can't change the past because it's already happened, there is nothing there for you to change