Okay, Kyle Reese dies in T1. Then in T2, when John and the Terminator are under the truck (fixing it) the Terminator tells him that, " you are going to send your father (Kyle Reese) back into time". How is this possible if Kyle's already dead? Is this essentially a hole that can't be solved? Or is there a good theory out there?
Kyle is dead, but he also hasn't been born yet. Time travel is weird like that.
I think the confusion comes because we're looking at the events of Kyle's life from two different perspectives: Sarah Connors', and Kyle's own.
There are three immutable facts of everyone's life1. In order, they are:
- We're born
- Stuff happens
- We die
This is what'd I'd conservatively call a "personal timeline"; it's what your life looks like to you. Kyle's personal timeline is the same. From his point of view:
- He's born (in 2002 according to the wiki)
- Stuff happens
- He dies.
In real life, everyone has the same perspective of time: they see an event (Kyle's birth, say), and then they see the effect caused by the event (his death). Kyle sees his life the same way: he can't see himself die before he's born.
Time travel muddies the waters somewhat, because it lets us see an effect before the cause. In Terminator the audience sees Kyle's death, and then we see Kyle's birth 20 years later2.
This may seem like a paradox, but it's actually just time travel messing with our perspective of time. We see effect before cause, but Kyle is still experiencing his life the same as he would without time travel; from his perspective, the cause already happened. We just haven't caught up yet.
1 Four facts, if you count paying taxes
2 We don't literally see it, obviously. You know what I mean
For time travel to happen, it has already happened. If it hasn't already happened then it won't happen. Practical time travel can happen in the future, but has already happened and altered the past. If you have noticed any changes in the past few minutes then your personal time line has been altered, but you wont notice any changes because as far as you know it's always been that way. The terminator films are news reels from the future, but because they haven't happened yet, they are viewed as fantasy. This then causes a paradox. For something to happen it must have already happened. QED.
Quite simply, there are (almost) two Kyle Reeses. Sometimes time-travelers meet themselves, but this sort of thing is generally frowned on in science fiction; too weird I guess. The original Reese loops back from the future, and causes Connor's own existence. (In the Sarah Connor Chronicles, for instance, his brother brings John Connor to see Connor's younger self. But they do not meet. They do, however, occupy parallel streams for a while.)
It's not a plot-hole in fiction, it's a plot-hole in time-travel, and for many constitutes a reason why TT cannot exist.