[Arizhel]

>Out of all the branches of the space-time continuum, what's the chance that we are on the original one?

None, because there's an infinite number of branches. And every time someone travels back in time, it creates a new branch.

What'd be interesting is to do an experiment to disprove this: invent a time machine that allows traveling both backwards and forwards in time. Use it to send two people back in time. Person A goes first, and the person B warps back to a time an hour later in the same place, and tells person A a secret. Then person B comes back, then person A comes back an hour later. Have person A repeat the secret, and see if they met each other in the past. With a new universe created every time someone goes back in time, will person B go back to the same new universe that was created when person A went back in time, or will they go back to the original universe that person A tried to go back to, and which still exists without person A which would change the course of history there? Does person B create a new universe? Will person A have met person B, and will they have seen person B go back to the future before them?