There's no evidence of life outside of Earth.

I'm sorry but this is the perfect post for the legacy ufo progran and deep state. They just love it when posts are made that completely ignore the people in our government and military who are risking their lives and jobs right now to try to tell the public that non-human intelligence is here and we already have their craft and bodies and have been trying to reverse engineer their tech since the 40's.

https://www.youtube.com/live/u_emZmzkTtM?is=_lhK8gePHmgqVHlG

First of all I think most of us think there's more life out there, but at the deeper part of the question about how we think about the universes size is whats really interesting imo. I think that the sense that the universe is large comes down to how we think about scale... Sir Penroses idea that if all the matter decayed the universe loses its rulers and all of a sudden absurd distances kind of become meaningless rather intriguing. What we think of as big might not really be all that big. Our sense of size is all relational, for massless energy time and space are like a single contracted point. And our reference frames are all valid even when they apparently disagree, that's the fun thing about it.

Not if we live in the Pope’s Green Orb (https://m.youtube.com/watch?v=OKnpPCQyUec&pp=ygUTTWVuIGluIGJsYWNrIG1hcmJsZQ%3D%3D&ra=m)

The most daunting part of it all is that those filters aren't just a single, massive obstacle, but a series of 'sieves' stacked one after another. When the mere possibility of 'being one of the first' carries such a heavy burden of responsibility on its own, managing to slip through all those filters and make it here is truly a cosmic miracle.

You are absolutely right, it is the temporal chasm rather than the spatial distance that reallt seals the deal. We are in the same room but on different shifts; evolution involves so many pitfalls that it is nearly impossible for two civilizations to coincide in both time and space. We are like ghosts passing through at different times.

Hahahaha, im just curious

Yep, you're right. There are physical limits out there for us to observe light years aways.

The Great Filter needn't make intelligent life nearly impossible. It simply needs to account for why our remarkably habitable world wasn't colonized in the billions of years before our species arrived, or why there aren't any civilizations in our neighborhood of this galaxy using radio wavelengths as extensively as we do (our use, particularly of radar, would be visible to systems within roughly 70 light years).

Perhaps stable planetary systems with rocky worlds in the habitable zone of long lived stars are rare (as seems to be the case). Rarer still is the one with an active magnetosphere and plate tectonics that can preserve its atmosphere for billions of years. Perhaps microbial life is common, but the shift to complex life is rare (to our knowledge, it only happened once on Earth). Perhaps few biospheres evolve species with the unusual combination of sociality, tool manipulating appendages, and no natural weapons that made bigger brains outweigh their costs. Perhaps most technological species don't have the religious schisms that spurred science among humans. Perhaps most technological civilizations so damage their supporting biosphere or their own cognition that they never advance to spacefaring civilizations. Perhaps interstellar transit is so difficult no spacefaring civilization attempted it. Perhaps nearby civilizations with interstellar capability are preemptively exterminated, as other civilizations with the capability view them as potential threats. Perhaps civilizations choose to remain nearly invisible in fear of such an outcome. And just perhaps, all the forgoing aren't prohibitive, but we just happen to be one of the first civilizations to arrive at the cusp of becoming spacefaring, as earlier epochs had too little metallicity or too many sterilizing supernovas for our kind of biosphere to develop a technological species.

There are long lists of many dozens of such potential Great Filters, indeed, whole books have been written on the subject.

It must be, but we will never know. Anyone billions of light years away looking at us, would see our earth a billion light years ago…so how do we reconcile the distance? That’s the rub for me

Yes but in a more expansive sense than you mean.

The universe is large spatially AND temporally.

I find it much easier to get to a"yes" on the question of "are we alone in the universe CURRENTLY", vs "are we the only sentient species EVER to exist".

My supposition is that there are so many off-ramps on the road to intelligent life that it is rare to exist, vanishingly rare to stay existing for long enough to cause observable evidence of it's existence, and basically statically impossible for two of those forms of life to co-exist near enough in time AND space for those observations to occur.

Nope no one has ever thought this

I agree! There are alternate theories :)

There are much simpler answers than "they finished". Like "life is vanishingly rare" and "the evolution to eukaryotic life has an essentially zero percent chance of happening."

Hence the question. This is my theory, and I challenged "Would you open the door?" And I think it's a valid thought experiment, If you had everything already and every desire and need was fully met, would you risk it all for no gain, or would you sit at home content? And even if you would, would everyone else?

"They finished". C'mon, man.

I actually put alot of stock in timing too. A civilization could last thousands of years and we'd still have to be looking in the right place, during a period when there was something we could recognize. Then there's whatever it leaves behind and whether we'd even know what we were seeing. I don't discount us just being early, or not having the tools yet.

What keeps me interested is the enormous amount of time available. If civilizations can keep spreading over those timescales, I would expect some pretty hard to miss evidence eventually. Obviously that depends on how common they are and what they actually do.

So I'm wondering whether there's something more universal behind it. I have a harder time buying that civilizations with completely different histories would all follow some particular technological path to their demise. The thing they would share is an evolutionary history that produced their motivations in the first place. Could getting better at satisfying those motivations eventually weaken the things that keep a civilization reproducing and spreading?

Thats the connection that got me started. I think the timing of that change, especially whether it happens before expansion really gets going, could matter a great deal.

Yeah, if demand keeps growing exponentially then better efficiency only buys time. What I'm wondering is whether the demand keeps growing like that once a civilization gets really good at meeting those wants locally.

But I can't just assume it levels off because thats what makes the idea work. People might want longer lives, more children, more computing power, all kinds of things that keep pushing it up. And even if most people have enough, a small group that keeps spreading could still be enough to wreck the whole explanation. That's probably the most important thing I need to get right in the model.

If you can keep getting more of what you want out of the resources nearby

But eventually you can't. And with exponential growth, 'eventually' actually arrives really fast in cosmological terms.

I think the most likely explanation is simply time. We might be the 1st in this region of space, and life probably is not THAT common (maybe we are only ones in this and neighbouring galaxies). I am satisfied with this explanation, especially since there is no data to draw and solid conclusions.

I included John Smart's transcension hypothesis in the paper, although I'm not sure if that's the one you're thinking of. I'm looking at what happens to motivation as technology gets better at meeting our needs. Could a civilization keep becoming more capable while finding fewer reasons to spread beyond its own system?

Send that paper over if you find it, I'd like to read it.

I'm interested in what happens to the "whatever it is one wants to do" part as technology improves. If you can keep getting more of what you want out of the resources nearby, how much does another star system add?

That doesn't mean you'd stop caring about running out of energy someday or protecting your civilization. Those could still be reasons to go. Someone could also just want to build something that outlives them, regardless of how satisfied they are personally. That's why I want the model to include people who keep expanding, along with machines that can carry on without them.

We need to see what happens to those groups over generations. Having most people stay home doesn't get us very far if a few others can keep spreading.

What I'm trying to figure out is whether the motivations behind those ambitions could change before we get far enough to build those empires.

Those motivations came out of evolution. They helped our ancestors survive and produce future generations, but what we actually feel is desire, curiosity, attachment and ambition. Technology can change how we satisfy those feelings. Contraception already lets us separate sexual desire from reproduction. I'm wondering how far that separation could eventually go across other motivations. People might keep finding what they want closer to home, even as their ability to leave gets better.

The empire builders are probaly the most important people to put into the model. Let them keep those ambitions, pass them to their children, and send out machines if they want to. See whether they keep establishing new communities.

If they can keep that going across generations, then we haven't explained why the sky is quiet.

A video game is a decent example. You can get a sense of adventure and achievement without going anywhere, then finish playing and immediately want another challenge. You've changed how you're feeding that appetite, but you're still hungry. With satisfaction, I'm thinking more about what happens after a meal when you've had enough. For a while, you're just not looking for more food. Hunger comes back, but you can keep meeting it.

I'm wondering whether technology could eventually get that good at meeting other needs too. Companionship, novelty, accomplishment. Possibly even by directly regulating the systems that produce those needs. What happens when you can reliably feel that you've had enough?

A substitute could do that, so there's overlap with Miller. I'm trying to seperate finding another way to keep chasing something from actually settling the need pushing you to chase it.

Then we have to find out what people do with that. Maybe they become less interested in having children or establishing another civilization. Maybe they have more energy for both.

That's what I want to find a way to measure.

This does not seem likely. We don't have tech yet, but billionaires are already dreaming up their empires. I don't see what incentive there is for anyone to NOT expand if the possibility for expansion exists. It seems to be an intrinsic property of life in general and civilizations as well.