I might be late to the party but, I just realised that time travel is impossible.
Because time doesn't actually exist objectively, all ‘time’ is to humans is the way we perceive the movements of particles. As particle shift from one form to the next it looks to our brains like ‘time’ is moving. But there is no time, it’s only things moving. So all time-travel would be is when all the particles are returned back to that ‘time’, just as they once were. And this is impossible, surely. You’d need a stupidly powerful machine to move all the particles in the universe back to where they were. Of course, this machine would have to be made up of those very particles in the universe, creating a paradox. Don’t forget your own particles, those would be all over the place – literally. You actually couldn't be there even if you could time-travel.
Also, just for good measure, the universe itself would have to rewind. It’s inflating at a phenomenal rate and would have to be returned to a specific point in ‘time’ so you could “be” there.
Am I wrong?