Can one change the past?

Back to the Future 2 is on at the minute, maybe that will help everyone's understanding.

Quote:

Originally Posted by Neversoft

If time travel were possible, would you be able to change the past?

You're probaly thinking 'Why won't you be able to change the past?'. Well, I just watched the film, The Time Machine. The film is about time travel obviously, A man's wife is murdered, he loved her so much that he built a time machine so he could go back in time and change the past so that she would be alive and wouldn't have been murdered that evening. But when he goes back, she dies again. He finds out that he cannot change the past, no matter how many times he goes back. She will die again because it has already happened. Even if they went somewhere else, away from the murderer, she would still die another way.
He goes far into the future to try and get a question asked - 'Why can't one change the past?'. He then finds out his answer. He built his time machine because of his wifes death. If his wife had lived that evening, then the time machine would have never existed. So how could he have used his machine to go back to save her.

It is explained very well why he cannot change the past, but in all over films where time travel is possible, you can change the past.
My question is - If time travel was possible, would you believe that you can change the past? Or would you believe that you cannot change the past, due to the reason above?

A very complex question indeed. Please do not attempt to answer this question without reading all of the above.

The film is flawed since he has already substantaly alterd the past, he changed how his wife died, he interacted with a large amount of differnt people, take the mugger, he now has money he didnt before, and mugged someone differnt from who he may have insted mugged. Becuse of this, a completey differnt chain of events could unfold, profoundly changeing the future "/
The idea of time in the film is the same as the terminator movies, although with a few more flaws, aka he the time traveler is still part of the defult time strand, hence he cannot alter time in any way, all the changes he has made have already happened and has been set, hence why in the terminator movie, its the time traveler going back to save the son, who turns out to be his father. The time line is predetermined. The flaw in timemachine is he changes his wifes dead, causeing him being part of the defult time strand to become unworkable in that theary.

There is also the all possibltys idea, where every possible evntualty happens, so if you time travel you create a new universe and alter that, while your orignal universes time line is unchanged hence allowing you to exist.

Others tend to allow the time machine, to seperate you from any existing time line and exist outside of it completey, only this method can actualy allow you to change your own time line, although the side effect is you have to deal with existing at multiple points, This is the one dr who exists in, hence why he cant go back on someones time line, At least without the universe being eaten that is "/

Then again, do any of these thearys realy work, since time is simply an axis of direction. You move to spaces along the x axis. Your no longer at your orignal point. You travel 2 spaces in time, the universe is no longer at the orignal point. Hence if you time travel to the first point, no universe will exist there, since the universe is now at a differnt point on the time axis. Hence time travel in the sence used in most fiction simply would not work "/

I've never gone back in time, so I wouldn't know. And I wouldn't exactly base my
knowledge of time travel on a movie.