In Pratchett/Baxter's The Long Earth, people learn how to 'Step', i.e. travel to another version of Earth where the dice were rolled differently. On some versions of Earth, the asteroid that killed the dinosaurs never hit, on others evolution lead to marsupials the size of brachiosaurs, others yet have seen some catastrophic event melting the poles and flooding most of the world, or the Himalayas never got formed.
In short, every Earth is separated from its neighbours by a degree of chance. For every event, there is an Earth that has had it happen, and one where it didn't. That doesn't go for every leaf that falls from a tree, but it does for the bigger things.
Thus far, every Earth shows what might have been based on events in the distant past (and I realize, we have a lot of 'past' behind us). I was wondering what would happen if we would have a major event in the present.
- Would a new Earth be added to the probability tree where it does or does not happen?
- Or would the number of Earths double (half of them having their history and evolution until that point plus the 'event', and the other half without it?).
- Or is the chain immutable, meaning that everything that can happen, is already predestined to happen on the worlds in the Long Earth? This would imply that there are at present (semi-)equal Earths that will start to differ once, in the future, this event does(n't) happen.
- Or would you imagine this working in a different way?
Additionally, all of the above are factors that affect one world only. How much of an impact do Steppers have on the above, by crossing over the probability boundaries?
Note that I'm currently nearing the end of Book 1, so if the above gets answered in later novels, please just say so.