kvs wrote:There is no hint of any advanced civilization on this planet outside the human one…..
Not only that, there's no evidence in the fossil record for any evolving intelligence besides our own.
Advanced civilizations in my opinion must exist on other planets. It is absurd for the Earth to be unique in the mind-numbing vastness of the(known) universe. There is more than likely a whole spectrum of civilizations out there at all stages of development.
I incline toward the view that civilizations undergo fairly rapid development, reaching spacefaring status after several thousand or a hundred thousand years or so. Considering the possible brevity (relative to the age of the universe) of the "developmental phase," at any given time there may be mostly just far advanced civilizations.
Also, the Earth is not a rule as to how long it takes for intelligent life and associated civilizations
to form. Other planets could see evolution of intelligent life much earlier. Some planets may never develop dinosaurs, etc.
I dunooo…it was said that the long dominance of dinosaurs led to increased emphasis on brains in mammals.
The question is why there is no EM pollution from these civilizations reaching us…..
So SETI and other such efforts are a waste of time.
Agreed, albeit for a different reason--advancing technology. It's been claimed that if there was peace and we switched to fiber optics earth would disappear from the radio map of the heavens; Sagan spoke of "tight beam transmission" in which case there'd be no leakage into space. If virtually all civilizations are far advanced it's no wonder SETI--with the possible exception of the '70s "WOW!" signal--hasn't produced results.
The only information we get out of these failed efforts is that the average distance
between advanced civilizations in the universe is very large.
If you mean civilizations which are indigenous to certain planets
they're certainly few and far apart. It is possible, though, that colonization has long been underway. Sagan estimated a single civilization could colonize the galaxy in a billion years--and I doubt he invoked some method of exceeding or bypassing the speed of light.
Some believe we have visitors from other planets, but I do not buy it since the distances are mind numbing as well. No less than speed of light travel is feasible.
It may not be absolutely necessary, if colonization has shrunk average distances. And it's just so rash to assume our understanding of what is possible is the last word…
You would need multi-generational colony ships to get anywhere and such entities are sci-fi fantasy.
I tend to doubt serious spacefaring is for purely biological entities. AI, cyborgs, whatever, seem more likely.
Btw getting back to this beneath-the-earth notion: It seems so implausible, even idiotic, that an underground civilization would become so incredibly adept at areonautics
How the hell would it develop and test aircraft while remaining hidden underground??