Finally, it returns

Thu, 19 May 2005 22:25:08 GMT

Well, seeing how long it's been since the last article, I suppose it's suitable that this should be about time travel. After all, if I had the ability to do so, I could send the finished copy back to some point where you were still vaguely interested in this idea of articles.

Time travel's a popular concept, and understandably so. The chance to become rich. To change your past. To change history. One of the reasons Doctor Who was so popular, and is even today. People are fascinated by the possibilities, and I'm no exception.

What types of time travel, in fiction, are there in most cases? I reckon there are about three main types, into the past: spectator, creating and changing. Oh, and those stories that don't actually pay any attention to the direction history has taken/is supposed to take, but they're not nearly so interesting.

Spectator is a rare case. Quite often you get characters being told they mustn't do anything, as it'll cause problems, but they go and mess it up anyway. One example of a spectator time travel I do remember is a show called "Crime Traveller", which was written by Anthony Horowitz. Two cops used a time machine that the one's father had invented to solve murders, by going back to when they happened and trying to see who did it. There were the usual rules (don't change anything, don't let your past self see your face (universe would explode), get back to the machine by a certain time, possibly the time when it was used from - though never explained why the previous versions originally using it weren't there - and anything you tried bringing back would disappear). The characters were therefore always trying to remain spectators, although occaisionally they did things which had happened the first time: for example, in one episode a model had been shot on the catwalk. A silhouette had been seen behind some fogged glass, holding a gun, but had escaped after being chased by the male time traveller, who hadn't managed to see who it was.

The two go back in time and the male cop decides to stay in the area hidden by the glass, to see who's there...he sees a gun lying there so goes to check it, and suddenly the shot is heard. He drops the gun and runs, just managing to escape from his past version. Lucky universe.

Which leads me onto the second type - creation. Personally, I feel this is the most likely type of time travel that would be possible, because it seems the most logical. Then again, considering time travel, if ever it happened, would probably be due to quantum physics, which pretty much continually defies intuition. So, this may well not be what happens if time travel is possible, but you never know.

Creation is my term for the type of time travel that involves creating itself. It's riddled with paradoxes; in fact the large majority of what is involved is paradoxical - where did that watch originally come from? It was never made. How old is it and how is it supposed to age then get younger again? However, most of the paradoxes are consistent, in that, for example the watch exists because it was sent back to go forwards to be sent back again (by the way, this watch example I'm using comes from the film "Somewhere in Time", a soppy time-travel love story, which is OK as a film if you like that kind of thing, and has a score by John Barry, the main theme to which is possibly my all time favourite piece, even if it is just a "pretty tune", as Jon would probably put it). To put it another way, consistent paradoxes are logical impossibilities that are not self-contradictory.

Of course, there are non-paradoxical creation time-travel, such as the example from "Crime Traveller" above. The character had a perfectly logical and consistent world-line, except for going back in time, and so did the universe. No problems; the point was simply that he had already been back the first time he went through. This may be the only type of time travel; it's the type I certainly believe would exist if any. However, I'll be coming back to this.

The third type is changing. This is often a fear of time travellers, even in cases of creation. Sometimes, though it's an aim. Thing about this one is the ways that the author deals with the changed history - the favourite being the good old "Trousers of Time", where the traveller(s) go forwards again in time to find everything changed, with only themselves remembering how it used to be. Having accepted this, people then seem to think that there's a problem with the grandfather paradox. It's not really any different - you simply end up in a different course, where you were never born and hence no-one will know or remember you. You can still go back in time and kill your grandfather because the you is the one from the other history, where your grandfather wasn't killed and you were born. It's not really too different.

Also, of course, there's time travel to the future (HG Wells' "The Time Machine") but no-one ever seems to view that as problematic. After all, the future hasn't happened yet!

Hold on.

What is the present; where is the past and where is the future? Why should we be able to change one with no effects, through time travel, yet not the other? Moreover, say we invent time travel, and someone travels forwards to see what happens, and discovers there's going to be a nuclear holocaust. S/He tries to stop it, but fails and returns. After the holocaust, another person uses a machine to go back and try to prevent it happening. Why can they not change anything, or at least not change anything without altering history?

I suppose it could just be that the difference is where the traveller goes afterwards. Backwards obviously will not be affected; forwards will. But it seems to suggest ideas along the lines of "the universe will collapse if you change the past and cause a paradox" are a little flawed without a better definition of past/present/future - something that there is absolutely no chance of having, seeing as there is no absolute time.

There's an alternative, though. Let's suppose that my ideas of creation time travel, where all the travel has already happened (which seems logical if you start ignoring the idea of a present and future) are true.

So what's happened to free will? (He didn't like it and went back to captivity...sorry.) If it's already happened, then surely you can't actually do anything about it - you'll go back and time and become your own great-grandfather or protect the saviour of the human race, no choice about it. If there is, then you lead yourself into inverse Grandfather paradox territory, which is no longer creation time travel. So, it's fixed.

But we've just assumed there's no distinction between past, present and future - there is a passage of time, but no marking saying YOU ARE HERE, with a backwards and forwards arrow. So, if there's no free will in time travel to the past, how can there be free will anywhere else...including the so-called "present"? If this is logically sound, how can there be free will?

Yet if it's all pre-determined...by whom? How? Does the universe 'know where it's going'? - though that suggests a past/present/future, again.

Maybe it's just as well time travel is impossible.

For the moment, anyway.

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A short while ago (7th May, I think it was), the first Time Traveller convention was held. Theoretically, the only convention. The idea being that all time travellers from the future can hear about this in the past and travel back to attend. Leading this to be a bit like the Crucifixion problem.

This is that if time travel were invented, and made available to large numbers of people, there are certain events that everyone will want to go and see. Such as the Crucifixion. Problem is, that means that the event of the Crucifixion, and other major events through history, should theoretically be cram-packed with time tourists. Yet there are no records of this. Suggesting either they kept it all very well controlled (not allowing people there or forcing them to stay hidden somehow), or they implemented some clever jiggery-pokery of Douglas Adams, such as works in The Restaurant at the End of the Universe (wouldn't be the first time he ended up prophesising the future), or - sadly - that there never is safe, controlled time travel available, or at least not to before time travel is invented (there are some potential methods that are considered to work theoretically but would not allow people to travel to before the machine was set into operation).

I don't know how the convention went, though.

Stream of consciousness

Finally, it returns