terminator

Originally Posted by muffles

Lol - I would say rather than him always failing when he tries to save himself, maybe he would find it impossible to fail to go back in time and save himself, when he is 19? Haha who knows...I have lost myself in the reasoning now

It's a bit mind boggling.
More likely still, of course, is that he fails to go back in time at all because time travel is impossible

If he has no legs, then the accident happened/happens to him. That can't be changed any more than you can change one of your own past life-memories or experiences.

Someone in an identical situation might be saved from the same accident by their future self. Perhaps neither of them ever knew the accident might happen, and it's just by luck that the future-person travelled back in time to the right moment to influence things. But of course the future-self never had the accident either, yet his arrival at that point is a certainty.

Or maybe the future-self remembers being stopped by himself as he stepped out into the road before a truck flies past. Having a nice chat and then saying goodbye. If that's the case then nothing the future-self can do will stop that event occurring. Whether he likes it or not he will travel back in time and have a chat with himself and save his legs.

If your 95 year-old self (you) appeared at your door, with incontrovertible proof of who he is, and says "You will live until you are at least 95"- then you're suddenly invincible, (although you could still be in a coma for much of that time ). He will remember the moment he opened the door to see his 95 year-old self, and in however many years it takes for you to get there, you'll remember what you said to yourself when you eventually knock on your own door and have the exact same conversation.

It's all so implausible that many-worlds makes (a little) sense, but it still means that sending things or people back through time is a pointless exercise if you want to change the things that actually happened to you.

It also means our fates are pre-determined, which is a bit depressing.