We sort of assume without proof that every civilization optimizes for continuation of its own existence. What if it's false and civilizations just detach from the utility function of evolution and choose not to exist anymore?

What we seem to assume is that every civilization optimizes for technological progress and territorial expansion.

That a species would be capable of interstellar travel and not spend millions of years aggressively exploring and colonizing the galaxy as a first priority just seems too alien.

Based on the excellent documentary series "Star Trek" I think it's safe to assume there are species that would colonize the galaxy.

But on a more serious note. You make an interesting point. Our entire history has been a fight for survival against a merciless environment (and other species). It's a core part of our DNA to colonize, grow, and thrive.

But assuming that is representative of what all life would go through may not be safe. It's hard for me to imagine how evolution would create life without the threat of killing off bad mutations, but that doesn't make it impossible. Definitely good to keep an open mind.

Our history has been a fight to survive and thrive where it's been possible to survive and thrive within the environment of our own ecosystem. Despite some exploration, we haven't exactly built cities in Antarctica or the ocean floor, because we can't thrive there. Whatever drive to colonize and grow that might exist in our DNA doesn't extend into space. There's no natural evolutionary path into space - it's unimaginably vast, it costs a ludicrous amount of effort and energy expenditure just to reach orbit, and once you're there literally every aspect of it is hostile to life, and every step is exponentially more expensive and deadly.

I can imagine a species with the same drives as ours, but which doesn't advance beyond colonizing its own solar system, or sending probes to nearby stars, because I can imagine that happening with us. I suspect that, as far as space exploration (much less long term colonization) goes, politics, economics and culture matter far more than our innate drive to find whatever's over the next mountain. We had the capability for manned lunar landings, but didn't follow up with moon-bases or a colony on Mars because that initial drive was fueled by competition and fear between superpowers. We gave up that capability because there was nothing interesting on the moon, and the public stopped caring, and anything but probes started to seem like a boondoggle.

And we're lucky enough to have a moon and a couple of nearby planets to keep us curious. How many technologically advanced but "landlocked" civilizations might there be, who don't venture into space because there's nothing to even theoretically colonize for hundreds, if not thousands, of light years?

Of course, if we had warp drives, things would be different. But the Fermi Paradox suggests that such things are either not possible, or somehow not reliable over the long term, possibly due to energy requirements or something.

Very interesting indeed, and that makes a lot of sense. I wonder if the Elon Musk style reasons would kick in (such as Earth is no longer hospitable to us because AI has completely taken over), which would definitely change the fact that Earth is a thriving environment for us. But short of that, I could definitely see you being right.

I think this is an overly glorified twist on a very simple and very possible "great filter" : pleasure.

Sustenance of a species requires a major sex/procreative drive. If we stop having at least two children per couple, on average, our population begins to decline. If couples only have let's say 1.5 children on average, we'd start on a path to an asymptotic extinction. And it's an oddly extremely fast thing. If people just have 1.5 children that means your population is declining by 25% per generation. At the current world population, that'd be a population decline of just under 2 billion people - in a single generation. To merely sustain our species we need each and every couple to produce an average of more than 2 children on average to account for the fact that some people are infertile, others will die before maturity, etc.

It's easy to see a million and one ways a species could accidentally drive itself extinct without in any way ever intending or "consenting" to such. Mass devices of pleasure that supplant sex and procreation as primary drives, worldwide perfect birth control and a species that does not choose to procreate sufficiently, social views that result in unsustainable procreative rates, etc.

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The one thing I'd add is that I think the above is extremely unlikely because of natural selection. Evolution will simply select for those that choose not to utilize said entertainment devices, or those that choose not to utilize birth control, or those that have differing social views, etc. The problem here is dysgenics, but that's a whole heck of a lot better than a population going lights out not with a bang, or even a whimper, but a moan.

Civilizations that choose not to exist will stop existing, thus stop being civilizations, thus stop being in scope for discussions about threats and promises of alien civilizations.

In the long-enough run, evolution will select for civilizations that don't get bored and opt out.

It might be a bit dark and somewhat controversial to think about in light of mental health and what not, but maybe there is a point where civilized entities advance past a need of a survival instinct and just decide to turn off the lights?

When you have satiated your thirst for existence, whats next?

To my mind this always seemed the likely default...I was going to say psychologically convincing but of course there isn't a cosmological theory of psychology (or is there?).

Lem's Fiasco is a good exploration of how we project our idea of culture, progress and sentience onto other notional intelligences in the Universe.

Or, as human civilization currently does, ignores threats to its civilization because it would be inconvenient to change in response to that threat.

That is somewhat the premise of David Brin's novel Existence. I don't want to spoil the premise, but it's a wonderful read.

You are disappointed there isn't an alien race that can shoot us from space with advanced weapons?

Yeah, actually. Alien sapience would (almost) undoubtedly have a fascinatingly different perspective than our own, and learning about it could better inform our model of reality. So what if they're more advanced? We will have to come to terms with our collective delusion that humanity is divinely exceptional? Worst case we get wiped out, which is going to happen at some point anyway, but it is more likely that any species with the technology to survive in space long enough to make interstellar travel feasible has little use for our world or its resources and therefore little reason to be overly aggressive.

There are those who would argue that math says they should wipe us out because we might one day be a threat to them, but that's a clearly bankrupt philosophy. If that's really how things worked, then every nation, tribe, family, and individual on earth should be doing their best to wipe out every other on the same reasoning.

An earth could a few hundred LY from us we might not be able to detect it(1).

I guess maybe the silence is because of such threats out there.

1-https://www.centauri-dreams.org/2012/05/31/is-our-civilizati...

I haven't read the linked article completely. But I think unless we're able to manipulate our Sun's mass or luminosity, it will be extremely difficult to make our civilization difficult.

s/difficult/detectable ?

Thanks. Can't edit anymore.

"it will be extremely detectable to make our civilization difficult."?

I dont know why people are downvoting this.

Virtually every single creature on earth has defense mechanisms against others. Stealth, evasion are very common among the life we know--why would that be so likely to be different for alien life?

Discovering type II+ civilizations at this stage in our own civilization would indicate our almost certain impending doom. That would be very sad news for us.

As opposed to the almost certain impending doom of human-created origin?

the history of life on this planet is a story of immense and intense suffering.

are you sure you want life to be such a common phenomenon in the universe?

do you think the sense of wonder attached to zipping about in spaceships firing weapons at each other somehow redeems all that suffering?

If given the choice, would you end the human race to stop their suffering? Is life not worth some pain and suffering?

i would absolutely do so.

no, no amount of "good life" is worth the lives that experience:

- burning to death in a fire

- dying slowly of cancer

- being a transatlantic slave

- dying in a concentration camp

- slipping into schizophrenia in a medieval society

to name a very very few compelling examples.

no future can redeem our past.

and how can you imagine these things happening many many times over through countless civilisations across the universe, but then regard it all as some delightful space opera?

well of course, those who shrug and carry on breeding, or those who manage to rationalise it all to themselves, they populate the future.

my sincere hope is that if a super intelligence emerges, it regards this world with a mind free from the survival desperation which being the product of an evolutionary process has imbued us with, and that it then rapidly sets about sterilising as much of its light cone as possible.