I thought the SG-1 S8 finale was an interesting take on the time travel plot, particularly because it also tied into another classic plot device: the so-called “groundhog day” plot.
If you want to improve the future in a very specific way (say, make sure the Z.P.M. remains hidden on earth rather than taken away), but you’re afraid of the consequences of modifying the timeline too much and make bad things happen (say, Carter not joining the military which in the canon means that earth falls to Apophis), how do you do that?
Well, you can realize that where there’s timetravel, there’s groundhog day: you can travel again and again, until the desired combination is reached. How? Well, bury a video camera with a video having everyone describe the future as they know it. Whenever this future is not correct, go back in time and fix it. This can end in one of several ways:
- The result is achieved. The team does not travel back in time, thus, having the Z.P.M. but still not causing any damage. Note that minor differences can occur (say, fish in O’Neill’s pond). However, no serious damage.
- A waaaaay better future is achieved — say, the Go’auld are eradicated and there is peace on earth. Stop going back in time, and count your blessing.
- The loop gets too out of whack — say, the time-travel device is destroyed. You’re stuck with what you have.
Nowhere near fool-proof, as we can see — but still, a reasonable plan in the face of dangerous circumstances, because it has (some) built-in safety features. We can call that “Implemeting Groundhog Day with Time-travel”…