Time travel isn't real because time itself isn't real. Time is a side effect of our perception of this simulated (without a computer) false reality that God has us experiencing/dreaming in (God is good, just saying) and even if you could time travel, you wouldn't want to because everything is as exactly as it should be. Even your mistakes and bad things that happened are important because they shaped you. It's not even important to try to make life perfect because life was designed by God as perfectly imperfect. Heaven/God is perfect and that's where we're gonna go eventually so just make the best of this hell (because this is actually hell) and wait patiently for heaven. Remember, God is eternal. (outside of time) because God is heaven, and God is real reality.