Droid803
Time travel in the DE universe must obey the Novikov self consistency principle, regarding bringing people from the past.
Stated simply, the Novikov consistency principle asserts that if an event exists that would give rise to a paradox, or to any "change" to the past whatsoever, then the probability of that event is zero. In short, it says that it's impossible to create time paradoxes.
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A common example of the principle in action is the idea of preventing disasters from happening in the past and the potential paradoxes this may cause (notably the idea that preventing the disaster would remove the motive for the traveller to go back and prevent it and so on). The Novikov self-consistency principle states that a time traveller would not be able to do so. An example is the Titanic sinking; even if there were time travellers on the Titanic, they obviously failed to stop the ship from sinking. The Novikov Principle does not allow a time traveller to change the past in any way at all, but it does allow them to affect past events in a way that produces no inconsistencies—for example, a time traveller could rescue people from a disaster, and replace them with realistic corpses if history recorded that bodies of victims had been found. Provided that the rescuees were not known to have survived prior to the date that the time traveler stepped into the time machine (perhaps because they were taken forward in time to a later date, or because their identities were hidden), the time traveler's motivation to travel back in time and save them will be preserved. In this example, it must always have been true that the people were rescued by a time traveller and replaced with realistic corpses, and there would be no "original" history where they were actually killed, since the notion of changing the past is deemed impossible by the self-consistency principle.
Basically, shortly after Mike was taken to the future, the First Event (read it in the techroom) happens, which results in a nuclear war on the scale that people basically stopped counting the dead. That resulted in many people being missing and never found. Mike was taken to the future, and since that happened, he was not seen prior to being brought into the future, thus there's no problem at all - everything is consistent.
Conversely, the jump to Sol has a much more out-of-universe explanation. It's basically standard sci-fi FTL with a bit of plot device usage as to why the whole damn allied fleet didn't jump there. It could have easily been "oh they have much better jump drives than we do...and we have a few fighter sized prototypes - take these!". I just picked something. I wanted to avoid BoE syndrome missions so I put a hard limit on the number of friendly capital ships present. Yeah, this is a very
meta-explanation of things.
I needed to get rid of the friendly fleet. I just picked a random explanation.
Yeah, the consistency principle
might just conflict with the entire idea of having FTL travel in the first place (not exactly certain about it), but I hope you're willing to overlook that like for every other sci-fi universe that has FTL travel and no going-back-in-time-and-causing-paradoxes. The long story short is no, they *shouldn't* be able to change events already recorded in history - they can't go back and prevent the attack on Earth because if someone did go back in time to try and prevent it, they obviously failed. Of course, they could still go back and rescue people like how they brought Mike to the future, but there's no real deadline for that....haha
If I've made any really dumb plothole...well...sorry XD
But sending him back with knowledge of the future is changing the past.
As a though experiment: If he simply thinks of it as an hallucination or dream, and never acts on that knowledge nothing really changed...did it?