Very sketchily, I’ll represent it like this: there is a possible world in which, let’s say, Hitler was not born, a possible world in which humans did not evolve, a possible world in which this universe did not come into existence, etc. Each of these possible worlds is successively less like the actual world that we inhabit, but they all are equally valid as possible worlds, and in a sense they all exist. So, it’s like parallel universes, kind of. Basically, you have to imagine an infinite cluster of infinitely diverging causal chains, where one possible world is one particular course along one of these causal chains; the ‘actual’ world is only actual in so far as it’s the one that we inhabit, the one we care about. But you can say, like I said before, that certain causal chains are ‘closer’ to each other than others.

Okay, so with regard to the fictional cases that are in discussion, there is a possible world, call it A, in which the Borg do not go back in time, one, call it B, in which the Borg do go back in time and “change history”, and another, call it A*, in which the Borg go back in time but our heroes stop them. Is A* closely related to A? Yes. Is A* identical with A? No. The causal chain in A to a great extent overlaps with the causal chain of A*, but from a logical standpoint, the two are distinct. You can call that “parallel universes” if you want, but I prefer to say that causal chain A* is the actual universe, because it’s the one we ‘inhabit’, the one we care about. I would make the same argument in regards to Tasha Yar & the Enterprise-C of Yesterday’s Enterprise.

As to #222, in general I think this stuff is fun, but I do believe Star Trek, as a franchise, has just about tapped out on it. The only reason I am enthusiastic about it being done again in STXI is that Bad Robot is doing it, and I think that team has done a great job with the subject on Lost.

Can’t argue with that…but what else have I got to do? (LOL)

If when the timeline is changed all that happenes is an alternate timeline is created or parallel universe is born, why the hell is the federation always making such a big deal of not interfearing the the past events?

I mean, using that logic then it would not be a big deal for Nero to go into the past and do….whatever….kill Kirk’s father, destroy the Enterprise, blow up Vulan, etc…. for Nimoy’s Spock. It would not effect Nimoy’s Spock. It would cause an alternate timeline or parallel universe to form.

I think that maybe this is the classic case of fans thinking about it maybe a bit more than the writers.

This is clearly an issue that still needs to be cover more clearly in the Star Trek stories, thus I dare say time travel has apparently not been done to death.

I can’t get on board with that. To me, if not for the interference of Picard in the natural course of history, the Federation would be losing a war with the Klingon Empire.
Unbeknownst to Picard, he is living in an alternate timeline due to his own interference under different circumstances. Of course she always comes back and changes history. Picard is going to make the same decision every time. But to me, unless the natural course of events is allowed to progress, then the result of the interference is indeed an alternate timeline.

The Borg are the ones who alter the timeline through the events of FC. Even though they are prevented from disrupting the birth of a human/Vulcan alliance, their very presence alters things somewhat–if only very subtly (the presence of Borg drones on Earth in the 22nd Century). Things will be slightly different in that timeline, as now Starfleet Intelligence will have some limited knowledge of the Borg.

I don’t disagree completely with your “loop theory”, but that does nothing to dismiss the existence of different timelines.

“Because common sense suggests that when the Borg tried to go back and change history, if they failed they could try it over and over again.”

But would they know exactly what failed and change their plan accordingly, assuming the enemy did not survive the attempt and return to the future? They could try the same thing over and over again and still get the same negative results. In fact, all things being equal, they would. That enemy would always come to the same conclusion and make the same attempt in the exact same way–getting the same result. In the case of the Borg, the Queen did not survive the trip. How could she then make a decision to change her tactics and try again?

Well the problem when you get too many is they start to cat fight.

In regards to TNG being an alternate timeline after the events of Yesterday’s Enterprise: I’m a believer that when something happens to change history, it had always happened that way. So in other words, Tasha Yar always came back in time and changed history.

Same goes with the Borg going back to stop the first warp flight.

The loop is part of the timeline, not a different timeline.

If you start to think too much about these sci-fi time travel scenarios, your head will explode. They don’t make sense, so just watch the movies or TV shows and enjoy them as entertainment.

Because common sense suggests that when the Borg tried to go back and change history, if they failed they could try it over and over again. Any enemy could go back in time and wipe out Earth at any point in our history. They haven’t.

I kind of like how the show Heroes handles changing history. Hiro tries to save the waitress from being killed. He succeeds, but she dies anyways. Because time and the universe demanded that she die, and she will no matter what.