Question about worldlines


Temporal Novice
John Titor describes the problem with messing up time and possibly erasing yourself from history by going back in time and changing things is that there are different "worldlines," and when he goes back he is actually switching worldlines. Basically, each worldline is different with slight changes so that in the end you have a worldline for everything that could possibly happen ever. The time machine has sensors on it to keep him to a world line that is as similar as possible to his (Usually within 1.5% for every 60 years or something like that) meaning that if he went back far enough, the world would be nothing like what he knew it as. When he "came here" there was a small change in the way things were folding out in time (such as different sports teams winning and books never being written). But what would happen if he brought back some sort of key technology 60 years and pretended he invented it. That then would put that worldline ahead technologically by 60 years. My question is would that increase the percentage of difference from the worldline he was coming from and if it did, when he went back and the machine stuck as close as possible to the worldline he was coming from, wouldn't he end up in a totally different place than where he came from originally? I do realize that there was already a difference when he went back and so he could never really end up in the same worldline that he came from, but wouldn't it be drastically different if this happened?
The concept of worldlines mystifies me. On what factual evidence are they based? Wouldn't mulitple worldlines need: multiple sets of matter, mulitple consciences, etc.? I just don't see this as being practicle. Maybe a worldline expert could chime in? /ttiforum/images/graemlins/smile.gif
Look at it like this. your traveling down river seems like a nice ride but you look back and you see thousands of other streams connecting to the one you are traveling on. But you were smart enough to carry some string with you and reel it out from your starting point. But you can't have an exact way of getting back since that string is twisting and tangling along the way. The further you go the more tangled and strung out it gets. I would have to say it would be much easier to travel backward then forward. Or even laterally would be a bit more intresting.