Dimension Split (Time Travel)

1. Is the split of the dimensions retroactive? 2. Could someone prevent the dimensions from splitting?

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1. Retroactive Split

Inquiry

The dimensions split at 1010 A.D. Does this mean that if two people travelled back in time from either dimensions after 1010 A.D., there'd be two of them in a single dimension?

Answer

Probably not. It is suggested that the dimensions are now complete, separate entities. Since dimensions are self-contained universes, Home World simply has the same history as Another up to 1010 A.D., after which it diverges. The Chrono series avoids paradoxes and probably would not create a case where the dimensional split literally happens at a branch on one worldline.

Inquiry

But can someone prevent the dimensions from splitting if they traveled back in time to Another World before 1010 A.D.?

Answer

This depends on whether the split of dimensions is protected by time traveler's immunity. Since acts of time traveling are, and since the dimensions, once split, are self-contained universes that exist all on their own, it would probably be impossible to prevent the split. Home World exists parallel to Another World and apart from it; even if you prevented the action that made things split in Another World, it still happened before you traveled back in time to stop it.

From: Common Questions