The story goes man created an AI but the AI had independent thoughts and motives and called itself Skynet. Skynet decided to exterminate all humans. T1 future Skynet decided kill John Connor out of existence by killing his mother Sarah Connor. In the future Skynet creates a time travel machine “Time Displacement Equipment”. In 2029 Skynet sends a terminator to kill her to end the line of Connor’s. The Resistance sends a soldier by the name of Kyle Reese before the time machine was destroyed. We find out that future Kyle Reese (2029) is the father of John Connor. How can Kyle Reese be the father when future John is around the same age range as Kyle? How can future John exist if Kyle is in the same time period as him. There is no valid explanation for this in the movies unless…..
These 2 theories are the only ones that would make sense of T1 and T2:
1. Only one earth, original events in the timeline were changed (altered):
In the 1980’s Sarah Connor married a soldier (no relation to the Reese family line) and had a baby his name was John Connor. In early 21st century (2000) Cyberdyne turns on their AI and Skynet is born. Skynet saw humans as a threat and decided to terminate all humans, original judgment day. John Connor who grows up to lead the Resistance (with the knowledge of warfare taught by his father). Many years later after the Resistance was established John saves Kyle Reese from the extermination camps. In 2029 Skynet knowing its destruction, in a last attempt sends a terminator to travel to 1984 to kill Sarah Connor to wipe John from existence. John Connor then decides to send Kyle to protect Sarah Connor in 84’ (before the time machine was destroyed). Which then leads to T1 and T2.
So John Connor’s original father was not Kyle Reese but someone else. The John Connor we see in T1 and T2 is from a altered timeline. When Kyle was sent to 1984 and impregnated Sarah a new John was created the John we see in T2. But then how did Kyle Reese get the picture of Sarah that we see in T1? In the 80’s Sarah traveled to mexico on a vacation to learn more about the culture and during that time the picture was taken. In this theory everytime people travel through time (and changes events in the past) a new timeline is created (like in Back to the Future), the original one ceased to exist. Which is why John Connor in Terminator Salvation says, “This is not the future my mother warned me about”. Because its not, its an altered future. If Kyle Reese 2018 (Terminator Salvation) dies John can still exist because John’s father is Kyle Reese from the original timeline.
These are the events that are a prelude to Terminator Salvation.
2. Multiple Universes:
The story we see in T1 and T2 are on alternate earths. For this theory to be valid there has to be numerous alternate universes. Original earth (earth 1) a soldier (descendant of Kyle Reese) impregnates Sarah Connor (in the 80’s just like in T1) and has John Connor who grows up to lead the Resistance (side note John's father was probably a soldier and was alive to teach John about the tactics of warfare). Skynet (future) learns of alternate universes (parallel worlds) and creates a machine to travel to different worlds (which is also a machine that travels through time). Skynet plans to exterminate all humans in all different earths (after they exterminate humans on earth 1). But John Connor leading the Resistance terminated Skynet before they can execute their plan. Out of fear of other alternate Skynets traveling to earth 1. John Connor thinks that without him other universes will lose to the machines. So John uses the “Slider” machine and travels to earth 2 and time travels to judgment day. John hides in a hidden facility and makes plans on destroying Skynet. John makes a call to all survivors and forms the Resistance. Many years later after the Resistance was established John saves Kyle Reese from the extermination camps. They became close friends. John tells Kyle Reese about his mother Sarah Connor (earth 1) and gives Kyle a picture of her. From the moment Kyle saw the picture he falls in love with Sarah (coincidently just like Kyle did in earth 1). In 2029 Skynet knowing its destruction, in a last attempt sends a terminator to travel to 1984 to kill Sarah Connor to wipe John (earth 1) from existence. But John knows that that wont matter because he is from a different earth. But to play along with Skynet (because this version of Skynet doesn’t know of other worlds) John sends a soldier to protect Sarah Connor (1984). Then T1 starts… So what happens to John Connor from earth 1? He travels a few years in the future to make sure Skynet is destroyed and to make sure the machines doesn’t come back. After that he uses the “slider” machine to travel back to his time period, back to earth 1….
In earth 2’s original timeline Skynet would win because they don’t have John to lead the Resistance. Since John (earth 1) saved earth 2, he changed the original timeline which creates a different future.
Of the 2 theories the first one is more believable then multiple universes. Because it fits well with T1 and T2 it's a prelude to Terminator Salvation. But with theory 2 there’s more drama.
So what do you guys think? 
