Re: Timeline branching going forward *spoilers*
How do we know that time travel wasn't responsible for the divergence of the Mirror Unvierse?
We don't, but that doesn't mean you can use that excuse to justify thinking it was.
“We have to learn again that science without contact with experiments is an enterprise which is likely to go completely astray into imaginary conjecture.”
- Evolution of the Solar System, NASA 1976, H. Alfvén & G, Arrhenius, p. 257.