In the model we propose in the post, the above parameters are held to be constant throughout the entire history of the universe.
You might also try a model in which these aren’t constant, because the presence of neighboring civilizations can change the probability of going from one type to the next.
Thank you for being concrete!
You might also try a model in which these aren’t constant, because the presence of neighboring civilizations can change the probability of going from one type to the next.