Some of those will have (or will have had) subcultures that generate self-replicating colonies, probes, or whatever. Those visit every stellar system in the galaxy in a very short time frame.
Possibly viable solutions include:
- We are simulated.
- Stochastic colonization leaves long-lasting uncolonized voids at all scales.
- Wolves. (Ecological wolves intent on making everything look natural, but since they get to be unitary, they can be as odd as they want to be).
But non-wolf Great Filter arguments have the same issues as arguing that all civilizations sublime, or leave, or whatever. There is always going to be someone who doesn't.
The problem is we have no way of estimating the probability of life emerging given favourable conditions. It could be 1x10^-100 for all we know.
So, how do we know that there was only one biogenesis, and not multiple ones that happen to resemble each other (i.e., that DNA-based life is the only thing that ends up working, and it occurred multiple times)? From what I gather, there are many markers in biological molecules, such as the direction certain molecules form (left vs. right, etc), and that multiple biogenesis events would have gotten these in random positions (i.e., your heart on the right side instead of the left side of the body).
Sure, each niche favors a different specialist, but why do you think that whichever process led to the emergence of life will be any good at producing competing specialists? I'd think that evolution of existing organisms would be infinitely better at this task, as existing organisms have both a numerical advantage and the strategic advantage of DNA (a "playbook" of previous successful strategies to draw inspiration from).
Very few niches are available for the emergence of life, even though there are clearly many available for the evolution of existing life. The available niches require a level of sophistication that spontaneous process cannot achieve but that evolution can achieve (e.g. photosynthesis).
The first generation stars wouldn't have had anything but hydrogen clouds surrounding them, but second generation stars would have had similar amounts of other elements to what we have today floating around them.
Given that "our" biogenesis event happened only the second time it could happen (here and in billions of other solar systems in our galaxy), where the hell are the second generation societies ? Didn't they survive the supernovas ? (possible, I suppose, but not exactly hopeful for our own chances of spreading across the stars). Was there some kind of large scale disaster ? But the question is worse than that, because they should have been spacefaring ... if they had anything like our numbers of satellites, we should have been able to find something, somewhere, right ?
Elaborate. If you're referring to the anthropic principle, I don't see how it's relevant to my argument.
Let's say that a typical planet remains habitable for 8b years and it takes 4b years from the emergence of life to the emergence of intelligent life, so according to the anthropic principle life had a 4b year window in which to emerge. Under the model where P(emergence)/time is tiny, the probability of life emerging in the first billion years is ~.25. Under the model where P(emergence)/time≈1, the probability of life emerging in the first billion years is 1. With even priors, the posterior of P(emergence)/time≈1 is 80% and the posterior of P(emergence)/time≈0 is 20%.
It's not scientific proof of anything, but it's enough to make me consider alternative explanations for why life is rare.
If there's no FTL, but civilizations can accelerate massive projectiles to near light speed, there's basically no defense against devastating surprise attack. And there's little accountability to allow retaliation.
Basic game theory says either they all destroyed each other, or the survivors are staying very, very quiet.
Just because something should be visible doesn't necessarily mean we'll happen to be looking at the right place at the right time within the right spectrum. There could be a lot we simply don't see.
It would probably be in the best self-interests of whatever species launched an attack to make it appear like a natural event in any case, so as not to draw attention to their existence from unknown parties (like us.) And a collision that could wipe out a civilization is clearly within the realm of natural possibility since it's happened on Earth in the past (without the civilization part..) so it need not necessarily draw attention to itself.
I'm pretty sure he's talking about the Zoo Hypothesis. i.e. our presence is known to other intelligent civilization(s), and for whatever reason they've decided to hide themselves and not engage. Like a village would refer to wolves in the surrounding forest.
For this to work though, you have to have one advanced civilization that has either absorbed the others ("unitary") or powerful enough enforce the rules. Otherwise it would be pretty inevitable that out of a hodge-podge of civilizations one of them would say screw it and engage.
For this to be an explanation it would have to be that this "great filter" is so hard to avoid that someone escapes it maybe once per few thousand galaxies per many billions of years.
Actually there is a way to tell if the world you're living in is not a simulation. Our world fails this test.
People forget that our planet has been through several catastrophic events that happened at certain times in our planetary evolution, and on other planets those events did not happen, or happened at different points in their evolution, or those events had a more severe impact. Things like the snowball earth phase, and the comet that triggered the die off of most dinosaurs. Maybe most planets are inhabited by symbiotic colonies of advanced trilobites 20 meters long crawling the ocean floor eating the abundant sponges. Have a look at the wierd and wonderful pre-cambrian life forms that somehow combined to create the kind of animalia that we know today. What triggered that? And earlier, what triggered the abundant bacterial mats to start forming mobile colonies?
Sure, life is everywhere in the universe but the trajectory that life took on earth will be exceedingly rare and we may never encounter another such planet even if we develop advanced star travel.
It could be even worse. Maybe we're not finding "life" because the only thing we have to compare to is life on Earth. Maybe there is life at different physical / time scales that we completely miss. Maybe what we call life, and specially intelligent life, is nothing special at all.
I find amusing that the general expectation is to find slightly different humans, with civilizations and communication and interstellar ships.
If we found an advanced civilization of intelligent robots, would we shrug and say "too bad they're not alive?" Of course not. So it's not life we hope to find.
Of course, this depends on how frequent you think intelligence is. I think most people assume it's very frequent.
They don't. They really don't. Do you honestly think you're the first person to ever think of this?
We already have way more money going into entertainment than into space exploration, it's not that hard to imagine that all sentient species eventually learn how to hack themselves into permanent happiness, and then conclude they have no reason to risk death on the final frontier.
This ofcourse requires some projection of our ideas of happiness onto unknown alien beings, but then why not also project boredom? If anything, we have seen that nothing in nature really stays the same. It is ever changing and evolving.
If those probes are Von Neumann machines they can spread throughout the entire galaxy in as little as a few million years. That's the crux of the Fermi Paradox - on galactic timescales any sufficiently advanced civilization should be able to expand its presence to the entire galaxy pretty easily and quickly.
Modern day gaming is the beginning of something much more significant in my opinion.
Furthermore, perhaps there's value in things going wrong, and taking risks? I mean, sadness is necessary to happiness. In Brave New World, to create a Utopia free of negative emotions, it is necessary to remove sources of misery- relationships, family, and so on, because when you lose a lover or family, you are miserable. How could you have a perfect reality without these things? No family and no relationships in the first place? Immortality?
But then, perhaps happiness is only relative as well? If nothing ever went "wrong" in your virtual reality, would you really ever feel happy?
Interesting psychological and philosophical questions.
a) Desire to explore nature's imagination instead of that of another human or AI. Perhaps we never hit a limit of computation, but there is an entire expanding, constantly growing in complexity universe out there to understand!
b) Even with artificial penalties, I doubt any virtual world could carry the same perceived risk as going out into the real world and risking getting eaten by a black hole or burned by an exploding supernova (assuming of course, you knew of/could tell the difference).
We can't stop interacting with the real world, but I imagine in the future most people wont. Current boredom is a reflection of our current technology and creative state in virtual worlds, not indicative of what the future will hold, it's only going to get better and while nature is amazing is so many ways human imagination trumps it. Whenever we do see something new we take it and add to it.
Until we have the computational ability to simulate all possible permutations of the universe there will always be much to explore because no matter what technology you create, its own creativity is bound by the culture which gave birth to it. If intelligent life and advanced civilizations are even remotely likely, there will be many different forms of imaginations and virtual worlds created around the universe, each born of a distinctly different culture or artificial intelligence shaped by a distinctly different history (unless there is a global optimum towards which all greater intelligences converge on, essentially a global optimum for natural selection).
If you were born on earth and learned an earth language as your first, how do you come up with a language that is entirely uninfluenced by the culture you grew up in, a brand new protolanguage? How do you even confirm that anything you created is so new that it stands entirely outside of your culture's previous ingrained assumptions and interpretation of reality? If your imagination (and thus the collective imagination of the civilization) is bounded, as it is by language, your education, etc., how do you know it can ever "trump" everything this big, big universe has to offer?
Some individuals will remain active in the virtual society. Active and with lots of technical ability.
I'll add one to the above: it might be that there are enough hostile forces, or at least the possibility of enough hostile forces, to make every technologically capable civilization conclude to travel near the speed of light to protect themselves from relativistic bombs. (Objects going very close to the speed of light. Impossible to detect in time to deflect, a form of advanced weaponry.)
Each alien civilization sees that there are no observable civilizations and decides that the ones that have existed either died or fled into near-the-speed-of-light vehicles. They rationally conclude to do the same, at least while they advance their technology and search for life. The unfortunate part is that time goes by much faster for us than it does for them, (which negates the advantage that many early civilizations would have had).
This might also involve an element of self-interest on their part. Perhaps intervention has been shown to produce dangerous results.
That might not be the right question, or at least is isn't the only pertinent question. Other quesitons: "why can't we see the ones that are around now" and/or "what happened to the ones that aren't around now".
If we are detecting civilisations feom the RF output, then consider how quicly we went from no RF output to nearly blowing ourselves to bits. Many civilisations could have committed suicide in a short space of time too. Many millions of them could have shone breifly and vanished millions of years before we even started looking. That is a tad fatalistic: we haven't managed to wipe ourselves out even though we threatened it to an extent. But there is another good reason why an older civilisation would be difficult to detect: efficiency. As a civilisation's technology improves, unless they find an effectively unlimited energy source, it is likely that they will leak less and less out: communicating point-to-point methods most of the time rather than by broadcast, containing and reusing what would otherwise be waste products of enery production/use. Of course they would never be 100% efficient, but they only need to be efficient enough that by the time the side-effects of their activity reach us they are not descernable amongst the background noise from the stars, black holes and other parts of the cosmos.
Evidence of other life could be passing us by right now and our attmepts to detect it are simply insufficient, in fact the more civilisations there are out there the harder the problem could become: the signals from each would interfere making the attempt to spot any one signal amongst the background noise (in part natural noise and in part that from the other signals) that but harder.
It is all moot at the moment of course: unless they are on our doorstep, to the point where we couldn't miss them, meaningful communication in our lifetimes is very very unlikely.
Of course there are other equally possible explanations, such as us being in a simulation of sorts.
"Consciousness is the only thing that is fundamental. Everything else is derived from consciousness, including this physical reality."
Similar to what others have said, I think the spectrum of 'intelligence' might be exponentially larger than anything the human mind can comprehend at this point in our development.
Since we're at the top of our planet's bio-hierarchy I think we tend to marvel at our own cleverness, yet wonder 'Where are the others like us?"
If other lifeforms are around us, they don't necessarily have to attempt to contact us or make themselves known to us in a way we could understand. There are millions of microorganisms around you right now, but they could never 'contact' you or even observe you in any meaningful way.
J. B. S. Haldane. Possible Worlds and Other Papers (1927), p. 286
In this tale, Earth would have several species achieving intelligence, all of them failing on interestelar colonization, and the last one, the wisest, figured out from the basic physics knowledge they develop, that this kind of travel would be impossible.
This basic assumption is very strong for me. Even if one civilization can travel at light speed, the multiple civilizations on our universe right now could be at millions of years of distance one of other.
If so, then shouldn't we be encountering these AIs?
It's also worth remembering that for 99.9% of our existence as a species, we lived on a much smaller energy budget. So maybe that's the norm, and planets where Saudi Arabia scale reserves of free energy are just sitting there for the taking are quite rare. Then, of those that do, what percentage successfully make the transition to become long-term spacefaring civilizations?
For a good read on the Fermi paradox, be sure to check out David Brin's The Great Silence.
Maybe there are a lot more evolutionary paths life can take on a world than just something similar to what happened here on Earth. Maybe typically it's unlikely for life to evolve to become much more than plant-like life forms.
I'm sure there are species in the universe which have evolved intelligence but I think they're much rarer than we would assume here on our perfect example world, Earth.
At the same time, it makes sense that more advanced life will try to be more efficient with its use of resources. This is a lot easier to do when you're smaller. Perhaps, they would try to minimize their size, allowing them _expand_ into _smaller_ space.
I'm sure this thought has been considered (e.g., see Men in Black 1), but I felt like sharing it anyway.
I've always believed that there was no evidence for ETs and life out there. I thought it was fiction. Then I spent all of last year trying to find legitimate proof of their existence. I just kept my mind open yet skeptical and looked at all the evidence I could find and simply analyzed the data. I was shocked that my conclusion was that ETs exist, they have been visiting us for quite some time, and they are generally benevolent.
You don't have to believe anything I say, in fact I wouldn't want you to. All I can ask is that you also spend some legitimate effort doing your research. Here's something to start your path down the rabbit hole:
Sigh, I hate crippleware.
I do love this paradox though, it makes for enjoyable conversation over a bottle of wine with just about anyone.
What if net-positive-EROEI controlled fusion is impossible?
We have only succeeded in producing nuclear fusion in two ways: atomic bomb primers and net-negative-EROEI reactors. Atomic bombs are technically usable as space propulsion (Google Project Orion), but the max velocities reachable are only on the order of 4-8% the speed of light. At that rate, interstellar travel is severely curtailed to only the closest groups of stars. We're talking over a hundred years to Alpha Centauri if you leave time (and reserve extra mass) for acceleration and deceleration.
Net-positive-EROEI controllable fusion is the only power source I know of that could allow anything near practical interstellar flight, so if it's not possible for fundamental physical reasons I'd conclude that interstellar flight is either impossible or nearly so.
If net-positive-EROEI fusion is impossible you could get very large, very complex, and very long lived intelligences but they'd be confined to their own solar systems.
For completeness I'll throw in two more, though they're ones I often see discussed:
(1) They're here, and that's what (some) UFO sightings are. They choose not to make explicit contact for some reason that we are not aware of, and that all visitors have so far shared. This could include an altruistic prime directive (intervention may harm us) or a selfish prime directive (intervention has been shown in the past to produce dangerous results, like post-singularity medieval warrior kingdoms or Nazis). A second reason for lack of explicit contact might be extreme alien-ness. Perhaps they are making contact but are doing so in ways that are so goddamn bizarre that we do not recognize it or culturally process it as such. The UFO literature is full of really wacked-out tales. Maybe some of them are true?
Sounds like a joke, right? Or the guy was insane? But imagine a "post-singularity" (for lack of a better term) intelligence that is utterly alien trying to comprehend our TV transmissions and then trying to make contact. Might the attempt not look something like that? Like some kind of weird dada-ist staged imitation of scenes from "I Love Lucy" and "Father Knows Best" with a dash of "The Outer Limits"?
Might you not also choose an isolated subject for safety reasons? Like a farmer in a field?
Sometimes I wonder if the weirdest most "dada" UFO cases are the most compelling. I would not expect alien contact to look as rational and methodical as meetings between human cultures. We're talking about an intelligence from another biosphere here, or a machine intelligence built by intelligences from another biosphere. Their thoughts might not even be translatable into English outside of the most objective domains like mathematical physics. Consequently unless they staged an undeniably dramatic contact event, we might be likely to dismiss their attempts to communicate as episodes of madness on the part of witnesses.
(2) The theists are right. We are the special creations of (or evolution was guided by) a supreme being and are unique. This is actually a variation on the "we are living in a simulation" hypothesis when you think about it.
He figured 133 years to Alpha Centauri but without carrying extra mass to slow down. I assume you'd have to double that at least if you carried bombs to decelerate.