I’ve always liked the idea that we’re under some sort of cosmic quarantine. Whether that’s for our benefit or “theirs” is up for debate.
First of all, let’s be clear about Fermi’s paradox because as usual a few people allude to the common misconception that it is making some claim about reality, or suggesting that the lack of evidence of ETs is inexplicable. This is not correct.
Fermi’s paradox is just saying that based on only what we know to be true at this time, there is no known counter to the proposition that humans should have seen evidence of ETs already. It is not suggesting that it is a picture that is impossible to fill in, just that right now we don’t *know *what that picture looks like.
In terms of the OP, it is plausible for some alien species to leave us alone because of some kind of prime directive or because they just aren’t interested. But for this to be the main great filter you would need millions of species at even a relatively “primitive” stage of development (I mean little more advanced than us) to draw the same conclusion and that seems implausible. It could be a piece of the puzzle though: maybe some other filter is responsible for their being few advanced species, and the few that make it decide to leave the newbs alone.
Slow interstellar travel requires that the travelers are adapted to existence in open space (long-term closed ecosystems, AI devices that don’t need any sustenance but energy, whatever). Given that, there’s no reason to be interested in planets as anything but objects of scientific study (which would be impeded if they interfered with the natural planetary environment).
They could have visited our solar system dozens of times – and might even have left all sorts of relics in the asteroid belt or Kupier Belt right now – without our knowing.
Does this hypothesis bring anything of value though, to the search for ET? It just might turn out to be true but for the moment it seems rather defeatist, i.e. “well nobody wants us to see/hear them so we should stop searching…” Maybe we’re the only ones or maybe they’re all hiding, but we won’t know for sure until we’ve looked everywhere.
Is the signal strength at 100 light years even detectable? The Voyager space craft have just left our solar system and we still talk to them but only barely. Granted their transmitters are not very powerful compared to a modern broadcast station but they are pointing their antenna right at us and we are pointing an antenna right at them. Even so, at this distance, the signal strength is only one-tenth of a billion-trillionth of a watt. Fortunately it is at a high frequency which not much other stuff uses on earth so we can pick it out of the clutter.
That is just out to 10 billion miles away. What signal strength would you expect at 100 light years away (about 588 trillion miles)?
I think they cover this on the following PBS space time episode (which is generally good info for this thread):
PBS space time: Why haven’t we found alien life
Basically they say our first TV signals are probably two weak to be detected at 100 ly, but our broadcasts from 60 years ago or so will be detectable much further out.
But anyway, the point is just that fledgling, primitive intelligent species like us are likely to be quite noisy and detectable for some time, even if later we develop perfect cloaking technology / live mostly in hyperspace / live mostly in VR / or whatever
Sorry for the apparent spam: The episode I posted previously is just about the fermi paradox, the details about whether aliens can see us was in a separate episode:
The problem with discussions about the Fermi Paradox is that we’re trying to talk about what a technological civilization thousands or millions of years older than ours might or might not do. It’s only been a little over 100 years since the very concept of the future being different from the past due to scientific advancements first occurred to us (roughly from H.G. Wells’s time). In that time, what we’ve imagined might come to pass centuries from now has been revised several times due to advances that could scarcely have been imagined previously; and it seems probable that we’re nowhere near the end of that process. The history of science fiction is filled with naive visions of the future based on the limitations on what was then considered possible. My guess is that we’re at least one or two scientific/technological revolutions away from what the future eventually holds.
But although I know you’re responding to OP’s imprecise “it does seem more likely than flying saucers”, this is not the correct analysis. There are no flying saucers. So the question is, given the data we observe no aliens, is the more likely explanation for the data that:
(1) There exist no aliens who can reach us;
(2) There exist aliens who could can reach us, but choose not to reveal themselves.
ETA: in your notation, it’s (1-P) vs Q, rather than P vs Q.
One thing that is left out of the Drake “equation” is the number of intelligent societies that are even aware of the greater universe outside of their world.
We see the stars and galaxies and look up and wonder. Water seems to be the universal solvent needed for life. How many of these water worlds are continually covered in ice? How many are continually covered in clouds? The aquatic intelligences of those worlds may never even think of the outside universe or have any reason to do so.
Our thinking is colored by our knowledge of the greater outside. For a cloud or ice covered world, which seems likely to be many of the water worlds, that knowledge or idea of a greater universe will be missing.
The simplest reason that we cannot detect other space faring, or space aware, technological, intelligences is that there are none. Occam’s razor. Intelligent, space aware, space travelling, technological life may be vary rare. And until proven otherwise it may be that we are an almost unique species.
Our detection abilities at long distance are getting better all the time. And still we find nothing. We could be the first, the Ancient Ones, and others will follow. Or we may be a fluke, and anomaly that will not be repeated.
Too much of this sort of speculation relies upon a sort of Star Trek outlook. There are undoubtably many planets with life of some kind, many intelligent ones too. How many are aware of the outside, how many are insulated within the cocoon of their water world? This is nowhere in the Drake intellectual exercise, which is what it is, it should not be referred to as an equation.
It is not a given that other technological being like us exist out there at all.
That’s brilliant. We are the equivalent of an artist starving in a garret; once they make contact, and start paying us what we are worth, all that creativity will vapourise, and the artist will become fat and decadent.
The correct answer is “insufficient data, I don’t know.”
There are a lot of alien specialists in this thread who have extensive knowledge of the psychology of aliens and will tell you all about their probable and plausible courses of action. But before you take any of that into account, you may want to ask how many actual aliens they’ve studied, first.
Consider, though, that it’s really difficult to understand the psychology of terrestrial animals. We even struggle very hard to understand close relatives, like chimps. When people tell you “oh, aliens are going to act like this” when dedicated researchers who have spent their lives observing familiar species can’t accurately predict their responses or understand their reasoning… well, I’d take it with an ocean’s worth of salt.
If aliens exist, odds are their ways of thinking are going to be totally incomprehensible to us. Their value systems - if they have them - are not going to reflect the mamalian values we project onto other species. Their stimulus response patterns wont be based on the same patterns that commonly appear in life on earth due to common ancestry, and that will make them inscrutible beyond even, say, octopi.
Anything is possible. They might get a bizzarre, orgasmic high from being unseen by people searching for them, so they make crop circles as hints and then laugh blissfully as we go looking for them when they’re standing right next to us. Equally plausible and probable to Spock/first-contact, because we don’t have any data by which to draw up a probability or enough understanding to establish plausible scenarios.
It’s a big, big universe with a lot of chances for really weird stuff to happen. Odds are, what we encounter wont match up to the vary narrow band our limited imagination creates. There’s just too many possibilities.
I think the “Zoo Hypothesis” is very plausible because I, for one, certainly wouldn’t want to interact with humanity. Lengthy observation would show me that humans are an aggressive and violent species whose racist/nationalistic tendencies graphically prove that they can’t tolerate the relatively minor differences within their own species much less exposure to a totally alien race from off world.
I suppose that, if I had a very pressing need that only humanity could satisfy, I might chance it. However, as an advanced species that can literally visit an unlimited number of worlds and has technology that you can only dream about, what could you possibly have that could compel me to come anywhere near you?
Why do people presume that aliens would find our species abnormally or repugnantly aggressive? Compared to what?
Tell that to the people being anal probed.
Well, lets hope that the agent in charge of our account is a moral entity, and that he is not like a music agent that would encourage artists to burn himself out on drugs and get to keep the royalties.
They could also be waiting for an optimal time. What could have happened if you had given mozart or beethoven a copy of “Cakewalk”? Would it have increased their productivity and therefore, their creativity, or would it have hampered them?
There could be a time when our artist getting access to advanced technology could create a burst of creativity, maybe our last burst that is based primarily upon our original ideas and cultures, influenced by a greater culture.
Right, but the thing to recognize is that, if there are countless species out there, then there is likely at least one, or maybe much more than one, that is similar to ourselves. That there would be species that we would not recognize as civilized, intelligent, or even alive, is entirely probable (as well as vice versa). But to say that there are countless species out there, but there are no species in the entire universe that would be similar enough to ourselves to draw some comparisons is more of a stretch, IMHO.
Then there is the fact that speculation, even idle and useless speculation, even speculation based on wild guesses and assumptions, is much more interesting, and even sometimes productive than simply stating “I don’t know.”
There are some basic ideas we can speculate upon, based on the principles of life and growth and what it takes to become a space faring species. For instance, you would not be likely to encounter apathetic aliens unmotivated to go to space, as they would not be the ones that are coming to you. Any species that crosses the interstellar void needs to be capable of some sort of logic, even if it isn’t comprehensible to us, it needs to be capable of some sort of tool making and usage, even if we don’t recognize the tools, and it has to have some sort of curiosity and ambition to sate that curiosity, or it would just stay home.
Given the energies involved in space travel, any species that is capable of meaningful interplanetary travel, much less interstellar, has access to technologies with tremendous energy potential. What is tremendous energy potential but a weapon looking for a target?
Any species that has come out this far has had to have managed to find a way to not use its technology for destructive ends, or it would have eliminated itself. We are certainly not at that stage of cultural development, yet.
This is one of the more plausible Great Filters. A species might develop easy interplanetary travel using powerful nuclear rockets or propulsion beams; but these technologies can also be used as powerful weapons, capable of destroying habitats and cities in a variety of ways. Eventually the interplanetary culture destroys itself using these terrific energies long before it reaches the stars.
Humans show endless fascination with any number of animals that are extremely violent - people love chimpanzees, who are utterly vicious sons of bitches.
in any case, though, humans are quite a bit more cooperative than they are violent, and a cynical political observation doesn’t add much to the discussion.
I think that’s true, if you add “self-replicating” to the list. Otherwise, if it is a species that is expansionistic enough to leave the familiar confines of their planet, it would probably also want to settle on planets that enable its population to increase. Of course if the ship system (including the inhabitants) were capable of replicating, there wouldn’t be a need for the larger environment and carrying capacity of planets, just a source of replication materials, preferably outside a gravity well.