Non-interaction
Source: TW
I have not seen all the Star Wars movies but it involves numerous alien types various planets all over the galaxy. That makes an attractive and engaging story. At some point in my youth independently of seeing any Star Wars, I too used to think of the plausibility of such a universe, with numerous alien species interacting in interstellar conflict. I thought we were not yet part of it as we were primitive and uninteresting.
However, the more I thought I of it, the more I became Fermian. That will remain restricted to the realm of cinema fiction. I believe what is closer to reality is that there are indeed numerous alien species but they don’t interact like the Star Wars aliens. Instead, each type mostly remains on its planet. If they do interact, then they do so at the level of microbial life – like bacteria and archaea interacting to give rise to a new life form that includes us.
Extinction
Source: TW
I recently heard the famous Israeli astronomer Avi Loeb talk about intelligent aliens, objects potentially generated by them. I agree with him that by the “Copernican principle,” there should be a lot of intelligent life in the Milky Way. Even conservatively, there have been/are 300,000 to 3 million planets with such life in the Milky Way. But where I depart from him is that even hyperintelligence cannot break the shackles of biology – i.e., species life-span. An intelligent species that arose somewhere, say, a billion years ago, is unlikely to remain on that trajectory of a billion-year headstart. Rather, it would have gone extinct by now. I think that would apply even if they achieved much deeper intelligence than modern Homo. Hence, unlike him, I doubt they are around or managed to spread around the galaxy.
Entropy
I think life anywhere in the universe would have to exist in an entropic “sweet spot.”
Too little entropy and everything frozen in excessive regularity.
Too much entropy and there is too much disorder for the molecular structures of life to persist.
There are relatively rare belts that allow such a regime. But given the enormity of the number of stars in the Galaxy we can still say there might conservatively up to 300 million stars that have such conditions for supporting replicating life. However, dormant life could spread over greater zones.