Sorry it's been so long since my last post. Life intrudes as it so often does.
This time I'd like to turn my attention to movies and some of the ways in which writers and directors have looked at time travel, both the paradoxes it creates and the ingenious ways in which they try to get around them.
In this post I'll look at the movie The Time Machine, based on the book by HG Wells. It's important to note that I'm talking about the movie since it takes a departure from the book in several important aspects. In the case of this post, it's in the way that the hero is prevented from changing the past.
As those of you who've seen the movie will know, the hero is prevented from saving his fiancee by the intervention of time. Every time he goes back in to the past to save her, he is prevented by the machine never arriving at the right time. The reason given is that since he invented the time machine purely to be able to go back in time to save her, if he then saved her he would negate his reason for inventing the machine in the first place. In short he would create a paradox.
On the face of it this seems like a cunning plan to prevent a paradox from occuring, but it leaves us with two problems. The first is of course, how does the machine know? Or failing that, how does time know? Conceivably he could be going back in time to do any number of things such as investing in a company who's stocks he knows are sure to rise. So how does the machine know that he is going back in time to save his fiancee? The fact that it does know implies that the machine or time is both sentient and probably telepathic. It knows his plans, knows it will create a paradox, and actually works to prevent them.
The second problem is much more difficult to get around. There were multiple ways in which he could have saved his fiancee. His plan which was very simple, was to go back to that point in time and rescue her from the gunman. But he could have done a great many other things to prevent her murder. He could have gone back a little further,perhaps to that morning and rearranged her day so that she would not be walking along soon to become crime scene later on. He could have gone further back and arranged for her to be perhaps overseas on a holiday at the time of her impending murder. Assuming the gunman was later identified he could have gone still further back, and had him arrested, prevented him from getting hold of a gun, or even stopped him from being born.
All of these actions would of course have created the same paradox, and so presumably the time machine or time itself would have had to have stopped him. But how? The machine would have had to have known at every step what his plans were. Or it could have simply prevented him from ever going backwards in time at all. In the end to completely prevent paradoxes from occuring it could only have done it one way, it would have become a one way time machine - it could only go forwards.
I'm sure you'd agree, that's not the sort of time machine we want to imagine.