Fermi Paradox: If the Universe Is Teeming with Aliens, Where Is Everybody?

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.

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.

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.

Modern day gaming is the beginning of something much more significant in my opinion.

Edit:

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).

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.

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.

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.

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: https://www.youtube.com/watch?v=7vyVe-6YdUk

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.

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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?

http://www.ufoevidence.org/cases/case708.htm

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.