Charles Phipps wrote:
The existence of parallel realities does not necessitate parallel realities from time-travel.
No, but common sense does. The idea of one timeline "overwriting" or "replacing" another is silly if you think about it -- it requires a "before" and "after" version of a particular set of events, a particular span of time, and how can a single moment in time come after itself? If there are two or more different versions of a specific date or span of time, then by definition they coexist simultaneously. It may look to the time traveler as if one comes before the other, but that's just because the time traveler has gone back and experienced the same span of time again. The altered timeline subjectively
appears to come "after" the original one, and thus the time traveler may perceive it as a "replacement" for the original, but as far as any objective observer of reality is concerned, the two versions of history exist at the same time, in parallel
. A different timeline cannot be anything but
a parallel timeline, regardless of how it was created.