I was thinking about time travel in pop culture last night and an interesting idea came to me. There are 2 types of time travel the way I see it 1 time travel that is dependent on going back to be able to go back in the future and 2 time travel that isn't dependent on going back to allow u to go back in the future. Of the first type I have 2 examples and of the second I have two examples which I'll list, but the conundrum I mentioned I will put at the end. The first type examples I have are Terminator and the Artemis Fowl books. The second type examples are the Back to the Future movies and Harry Potter 3. I'll be happy to discuss with u if u think I am wrong about this but the conundrum first. John Conner sent the man that is his father back in time to impregnate his mom, who sent him back to do that the first time?