/me wonders if Andrus will show up to help explain things...
Yes, Anna, there was a team from Utopia who showed up in "Lois and Clarks." As for when they'd show up, whenever you feel like it, pretty much. Most FoLCs probably won't think of them if you don't mention them, or, if things turn out okay without them, you could just say they knew that things would work out and didn't want to interfere unnecessarily.
If you do need them to show up, they'll try to do so at the time when they're most needed. It's up to them (and you) to determine when, exactly, that is.
As for what Terry was saying, there are a variety of options.
You can have one single universe which can be changed by time travellers. The travellers are outside of the timestream when the changes take place, and so are unaffected. Tempus existed. He went back in time to change things. Now Utopia doesn't exist, so the man who would have become Tempus (if he's even born) will not grow up in the same way. Tempus still exists, however, because he separated himself from that future when he went back into the past.
There isn't really support for this theory in L&C canon, though, because in Tempus Fugitive, Tempus threatens baby Clark. Future Clark starts to fade, even though he also went back in time. Tempus, however, does not start to fade, which, really, is kind of confusing but can probably be explained in some way or other.
There is, however, canon support for parallel universes. There's the Alt-Universe, and there was mention of an infinite number of others.
To explain this theory, I suggest listening to Doc Brown's mini lecture in Back to the Future, Part II. Basically, it goes like this...
A given timeline is linear.
A-----B-----C-
Stuff happens at point A which leads to stuff happening at point B which leads to stuff happening at point C. Time marches on at a steady rate of one second per second (unless you're travelling at close to light speed, but that's another matter), and life as we know it goes on.
Now, though, let's say there's a time traveller. He leaves from point C and goes back to point A. For him, A, B, and C have all happened already, but for everyone else, point A is the present and points B and C are just possibilities that haven't happened yet.
Now, our time traveller changes something in point A. This can have a major effect, no effect, or anything in between. It depends on what the change is and how important you think every little detail is.
If you think a butterfly can flap its wings in South America, thus causing changes in the air currents which cause other changes which start to work off each other, causing ever larger changes until you eventually end up with a thunderstorm over Europe, then you believe that even a small change can make a difference. In that case, going back in time and stepping on said butterfly will very likely cause a large change to the future.
If, on the other hand, you think that the weather is a large system affected by a huge number of variables and that whatever a butterfly can do will just be damped down by larger currents, then you believe that it would take a large effort to make a change (if a change is even possible) and going back in time to step on a single butterfly won't make any noticable difference at all.
In between those two views is a whole range of possibilities, and, since I have no personal knowledge of any actual time travellers, I can't tell you where along that range the truth lies.
You, however, are more or less free to determine where the truth lies for your story's universe. (Just remember that we did see some rules established in Soul Mates. You and your readers may or may not care about that.)
Now, let's get back to our time traveller. He went from point C back to point A. Then he made some changes to point A. We don't know what difference, if any, that will make.
One theory says that any changes he made were, in fact, already made before he left, so that when he goes back to the future, he'll just wind up right back at point C. That can make for a cool story, where you explain to the reader just why that change had already happened and why he didn't know about it before he left. It does kind of narrow your choices, though.
Another theory (Doc Brown's), says that making any change will result in the creation of a new timeline.
A----,,,,B,,,,C,,
........\___B____C'__
(The periods are there because the boards delete extra spaces. Ignore them as best you can. The commas indicate the old timeline, which may or may not still exist in another universe.)
Here, because of the changes, there's a new future. Shortly after point A, the time traveller's changes cause things to happen differently. From there, history will write itself out along a new direction, leading to a new future with B' and C' and so on. Whether or not the original point C still exists in some parallel universe is up to you. The thing is that to anyone other than the time traveller, the timeline now looks like this...
-----A---B'----C'--
They don't know there was a branching. They don't know that things were supposed to go to B instead of B'. They just know that after A, what happened was B' and then C' and so on.
What happened to the time traveller is up to you. Generally, convention says that he continues as he was. For him, history looks like this:
A----B-----C-- ~ A---B'----C'--
He lived through A, B, and C (or, at least A and B were established history for him), went back in time at point C (causing a personal discontinuity which I've denoted with a ~ ), and is now living in a new timeline. This means that when he gets to C', he'll be older than when he left at point C, because he'll have lived through A, B, and C in addition to A, B', and C'.
Other theories say that, since he wiped out point C, he no longer exists, either, and the universe, thanks to his changes, will simply continue down the new track without him.
It's up to you to decide what works and what doesn't. As long as you stay consistent, you shoul be fine.
And don't worry, even professional authors have written things that, to me, make no sense. It can be hard to avoid it. Just do your best, and know that your readers are willing to give you some leeway because they can't say how things should work, either.
Paul
