"If you think time travel is like a tower - one moment is put on top of all other moments, and order/causality is maintained at any time - then any attempt at time travel would either be rectified instantly, either by recreating the only possible timeline, or by recreating another timeline, erasing the change (depending on the amount of determinism in the universe)."
Feel free to be the first
Please review the linked page for context.
If you can think of something better than this,
please add it to the database