How would altering past events throughout the series’ timeline effect those that occurred after it?
bloody-sauce
Banned
Hypothetically speaking, let’s say Aasim was a super genius all along, and miraculously found the right materials to build everyone time-traveling devices, 5 years after the events of Season 4.
He and the others then decide that because they can theoretically undo past events, such as the deaths of Ms. Martin, Marlon, Brody, Sophie, Violet/Louis/Tenn, and pretty much any other kid from the school that died, they should definitely do so.
If they went back in time and prevented the deaths of anyone/everyone who died, which reality would they “return” to?
Reality A:
A new future that’s different from the present they traveled from, where the deaths of their friends never occurred when they did, therefore altering the continuity from which they came, which lead to the creation of this new one 
Or...
Reality B:
The present they left before traveling back in time where everything is still the same, due to the altered past creating a separate continuity in which their friends are alive 
Is there another way altering the past would change the present/future I haven’t mentioned?
Would it be worth it, traveling back and undoing the deaths of everyone at the cost of all the memories and possibly friendships that have been formed?
Comments
With reality A, the Ericson kids would no longer remember traveling to the past, because the outcome would erase their selves that had done so, and their past selves would become their only selves, with no recollection of what they did not witness, who’d then live onward, or die, from the moment the natural coarse is changed and their friends are saved.
In order to save everyone from the school who died, they would need to travel before the death of the first student, save them, and live rest of that past saving all the others who will die from dying, until the day Marlon, Brody, Sophie and Minnie meet the Delta in the woods past the safe zone. From there, they’ll either have to avoid being discovered by Lily and her crew, or fight them until they win, although the kids who were saved from death are likely to die fighting back, so avoiding the Delta is their safest bet before returning back to their future where everyone will be alive, or their present where nothing will have changed at all.
If they wanted to retain their memories of everything that happened up until saving their friends AND be with them, the Ericson kids would just have to stay in reality B after saving everyone, along with their past selves, where there would then be two of everyone who came to the past to stay.
If the first kid or Ms. Martin died early in the apocalypse, and the teens travel back to the beginning where they’d live the rest of their lives up until the time TFS takes place or go back to their present/new future after saving everyone, they’d be 8+ years older by the time their friends reach their ages before traveling.
Why can’t they go back in time to warn people about the apocalypse, providing evidence that they came form the future, a few years in advance so that people can better defend themselves?