User blog comment:Crimson Storm Mich/Future Units Preview v2/@comment-27498603-20160922033354/@comment-27498603-20160923231602

Changing history creates alternate realities, that is a constant fact of time and space. If you went back in time and changed even just one thing it would create an alternate reality. Time is that fragile when messed with, it creates alternate realities. Even if it's a very small and insignificant change it still creates an alternate series of events aka an alternate reality.