There is very interesting Video series by Issac Arthur about this topic
https://www.youtube.com/playlist?list=PLIIOUpOge0LulClL2dHXh8TTOnCgRkLdU
After reading Jacques Vallée book:
Passport to Magonia: From Folklore to Flying Saucers
i wonder, do alien civilisation at certain point in there existence,
Build artificial "universe" where they have better living conditions ?
From this point of view we are "alone" in universe, while more advance aliens life in realms, we not understand...
In my opinion, the biological phase of intelligence should be extremely short in astronomical terms. There are only two possibilities.
-Exterminated by a natural phenomenon, after a bucolic existence in perfect balance with nature, which would be unintelligent.
-They survive using increasingly sophisticated technology.
In the second case, survival should include the extension of life by technological means and (reaching a certain level) by the modification of the organic parts that deteriorate more quickly, such as the teeth, stomach, heart, and the ability to see well.
We have already achieved that but in my opinion the process will not stop here and will continue towards a form of non-biological immortality.
These entities should not be interested in contacting biological beings like us, except for scientific purposes, but for that it is not necessary to land in front of the White House and ask to speak with the boss, since his technical means of exploration must be fabulous.
Some of the earliest galactic civilizations, if they exist and have survived, may have several million years of technological and intellectual development.
And of course they did not communicate by radio emitting Wow signals!!
