A Book Metaphor

Let us compare a timeline to a novel. Imagine that the novel has ten chapters and that, for a later edition, the author revises the text from the beginning of Chapter 6. Thus, in the later edition, Chapters 1-5 are as before whereas Chapters 6-10 differ. A reader can compare the two versions. He might notice that character A who was still alive at the end of Chapter 10 in the first edition dies in Chapter 6 in the later edition.

This does not affect the fictional experience of the A of the first edition. He still lives until and beyond the end of Chapter 10 even though his counterpart in the later edition dies earlier. Another character B might be entirely cut out of the later edition. However, although B does not exist in that later edition, in copies of the first edition he continues to enjoy whatever experiences had been allocated to him in that edition.

No one (usually) publishes an edition in which, after Chapter 5, the text splits into parallel columns presenting the earlier and later versions of the narrative. Instead, we are presented with a volume containing either the entire original version or the entire revised version. If all surviving copies of the first edition were to be destroyed, e.g., by burning, then it would not make sense to ask at which point in the text the paper began to burn. It all burns together. Similarly, if timelines succeed each other along a second temporal dimension, then an entire timeline, when replaced by is successor, recedes into the past of the second temporal dimension - but its inhabitants are unaware of this. There is no moment in their timeline when they cease to exist.