A great question that humanity faces is this: Given the age and size of the Universe, why don’t we see evidence of alien civilizations?
This is the so-called Fermi Paradox: “Where is everybody?”
My interpretation had always been the very pessimistic view that technological civilizations self-destruct. Meaning, atomic bombs or super-virulent viruses are created that wipe everyone out, just as we’re getting started. There are lots of ideas though, and there are reasons to think that extinction is not inevitable. Perhaps humanity’s future is actually bright, rather than explosive.
Let’s presume at least one alien civilization exists. Why is it so silent out there?
These ideas overlap, but here are some hypotheses, neatly summarized:
“Upon developing world-destroying technology, intelligences wipe themselves out.”
Would every civilization do this? Every single one? By itself it doesn’t seem plausible. So perhaps there are other, more realistic reasons.
“Instead of expanding into outer space, civilizations compress information density until creating black-hole-like conditions and disappearing from the observable universe.”
This is perhaps the most optimistic possibility. Instead of expanding out we create simulated universes and live in those. It seems a good reason for why, even if most civilizations wipe themselves out, the remaining civilizations are invisible.
“Alien civilizations have a Prime Directive not to interfere with other life.”
Seems to require every civilization to be following some rule.
Phase Transition Hypothesis
“Life is periodically wiped out due to incredibly destructive natural events, which we are only just emerging from.”
Is life that rare? The hypothesis is a little small in scope compared to the amount of time the universe has been around.
Rare Earth Hypothesis
“Life is super rare, intelligence even more so.”
There are billions and billions of plants, and the arguments for why intelligent life requires such exact circumstances seem somewhat artificial. Life may be rare, but it may be hardy and simply end up traversing a different Hypothesis.
“It is costly to move about the Universe, so aliens communicate in an unknown fashion.”
Related to Transcension.
“Humans are as ants to aliens, and we have very little to offer each other.”
Radio Silence Hypothesis
“Aliens either use different methods of communication than we know of or are purposefully silent so as not to influence nascent intelligence.”
Evil Alien Hypothesis
“Evil beings wipe out any life that reaches a certain level of sophistication.”
I find it unlikely because humans have become more friendly as we’ve aged, so aliens would probably experience the same phenomena.
The Self-destruction and Evil Alien hypotheses are truly disheartening, but there appear to be good reasons to suspect them false. The rest of the hypotheses (and there are more than just these) seem basically neutral or positive predictions for the future of humanity.
I certainly have been disturbed by fear of the self-destruction of my species by some unavoidable technological weapons, such as biotech viruses, nanotech grey goo, evil artificial intelligences, or some other truly nasty event.
Now armed with some refreshingly optimistic hypotheses for our future (Transcension, Zoo, Ant, Expense, Radio Silence), perhaps we can rest easier.