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Thread: One Fermi Paradox Explanation

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    I am skeptical, for the same reasons I am skeptical of any claims to an explanation for the Fermi Paradox. There just isn't enough data to warrant staking a claim.

    A possible answer, but I won't be putting my money on any Fermi Paradox explanation claims yet.

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    I'd appreciate at least a summary explanation of what the linked page/article is saying. I dislike clicking otherwise blind links like this.

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    CJSF, here is the meat as stated at the site ;

    Summary:
    "The universe is probably filled with habitable planets, so many scientists think it should be teeming with aliens. But life on other planets would likely be brief and become extinct very quickly, say astrobiologists. In research aiming to understand how life might develop, the scientists realized new life would commonly die out due to runaway heating or cooling on their fledgling planets."


    Well, according to recent claims our Earth has gone through "runaway heating or cooling" during it's long period (~ 4 billion years) of simple microbial life before more complex life evolved. This includes 2 snowball earth epochs as well as multiple periodic catastrophic disruptions. No doubt that most planets don't have ideal conditions as seen in our own solar system, but even if 0.001%* of planets do end up Earth-like then that's still plenty of them out there to allow intelligent beings to evolve.

    * a reasonable number pulled out of my...hat.
    Last edited by Spacedude; 2016-Dec-02 at 06:50 PM.

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    Their argument seems to be that there is a contest between, on one hand, the ability of a biosphere to regulate a planet's temperature and atmospheric composition, and on the other hand, the tendency of a more-or-less Earth-like planet to either go thru a runaway global warming, to a Venus-like condition, or a runaway global cooling, to a Mars-like condition. And that it may be rare for a primitive biosphere to win the contest.

    Their bottom line is that life of any sort (not just intelligent life) is rare in the universe, not because it is difficult for life to get started, but because it is easy for life to fizzle out soon after it gets started.

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    The linked article mentions Mars as a possible example of a world where life was unable to stabilize the biosphere, and so, died out, or remained in only a very simple form.
    From what I've been hearing, it's apparently believed that Mars had too little mass, and too weak a magnetic field to hold onto most of its atmosphere against erosion by the solar wind. That sounds more like a failure of the environment, than a failure of life to adapt to any sort of reasonable range of conditions.

    Given a sufficient mass and a stronger magnetosphere, it not at all clear that Mars would not be as invested with life as Earth is.

    There doesn't appear to be anything that would make Earth-like planet especially rare, so why should life, even in complex forms, be rare in the larger scheme of things?
    Last edited by Ross 54; 2016-Dec-03 at 07:53 PM.

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    Another explanation as to why SETI has failed, no alien signals have ever detected, no alien space ships, armies, colonists, tourists have landed on Earth is:
    simple, there were no meteors that crashed on those worlds during their dinosaur age, thus alien dinosaurs still exist instead of primates ruling the land and evolving into higher forms.

    Yes, you might suppose that given enough time some dinosaurs might evolve intelligence, or even lizards or birds could learn to make fire instead of just nests, but I dont see T-Rex with its short arms able to do so. Unless, ifcourse smart aliens learned to mate longer armed T-Rexs. Thus, after many generations create a genetic trait for long arms, just as humans mate horses, dogs, plants, and all animals for whatever purpose is needed.

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    ...I realize you're being (mostly) funny, but you know that Tyrannosaurs, with their tiny arms, were ONE of a NUMBER of dinosaurs, many of which were bipedal AND had reasonably long arms?

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    Ok, so why then didnt Dinosaurs evolve to create high-tech? Given hundreds of millions of years of their existence, dinos should have developed space ships to either colonize the solar system, or even to fly to other habitable planets in order to avoid extinction caused by meteorites. Ifcourse, a few nukes could've solved that problem as well.

    My point is that dinosaurs went extinct allowing rise of homo sapiens. If alien planets have dinosaurs, the only way for primates to rise to our level is for a meteor to hit their planet.
    Otherwise, just as on Earth, dinos would still rule preventing other species from evolving.

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    A few nukes would not have solved the problem. More likely they would have made things worse. Most likely they would have had no significant affect.

    Assuming that a large clade, like your "dinos," would prevent other species from evolving is assuming way too much. If you compare a clade that includes humans and is of comparable size to the clade of "dinos" implied by your comment, that human containing clade is of comparable age and longevity. Just because it happened first in humans doesn't mean it couldn't happen in some species of "dinos." For that matter, it could still happen to "dinos" sometime in the future. "Dinos" aren't all gone yet and some of the ones that are still around are notable for being among the most intelligent species on the planet.

    Evolution over large time spans is too complex to warrant any confidence in the claims you are making, in just the same way that weather is.

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    Quote Originally Posted by Gomar View Post
    Ok, so why then didnt Dinosaurs evolve to create high-tech? Given hundreds of millions of years of their existence, dinos should have developed space ships to either colonize the solar system, or even to fly to other habitable planets in order to avoid extinction caused by meteorites. Ifcourse, a few nukes could've solved that problem as well.

    My point is that dinosaurs went extinct allowing rise of homo sapiens. If alien planets have dinosaurs, the only way for primates to rise to our level is for a meteor to hit their planet.
    Otherwise, just as on Earth, dinos would still rule preventing other species from evolving.
    There is also no reason to believe that evolution on another planet, even if Earth-like, would follow the same path as it did on our world, and that anything even vaguely resembling either dinosaurs or humans would ever evolve.

    But you did touch on one reason for the possible lack of contact: even if life is common in the Universe, intelligent life, particularly tool-using and exploring intelligent life, may be very rare.
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    I think most of us would agree that alien life on another planet wouldn't necessarily be analogous to dinosaurs or primates, and that it certainly wouldn't need to follow the same kind of timeline of development as ours.

    But Gomar's suggestion essentially boils down to assuming that even if life is relatively common in the universe, intelligent or technological life is extremely rare (if cast in terms of the Drake equation, this would be thinking that fi of fc, the fractions of life bearing worlds that develop intelligence and the ability to communicate over interstellar distances, are very low). It's hard to estimate those, given our limited examples, but there actually is a certain sense in which Gomar is right: the fact that the dinosaurs were around for millions of years without developing any kind of technological civilization at least tells us that it isn't inevitable.

    This is a different answer than the one suggested in the OP, but at this point it seems just as reasonable a supposition.


    Edit to add: and Swift beats me by a few minutes...
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    Given the long time span involved, it seems possible that any evidence of a civilization created by advanced dinosaurs would have been destroyed by materials decay or buried so well by geological processes that we would be unlikely to find it.

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    Quote Originally Posted by Grey View Post
    It's hard to estimate those, given our limited examples, but there actually is a certain sense in which Gomar is right: the fact that the dinosaurs were around for millions of years without developing any kind of technological civilization at least tells us that it isn't inevitable.
    I am not sure that Gomar's argument supports the conclusion that it isn't inevitable that evolution will result in a species that achieves a technological civilization. Though I do think that merely our understanding of evolution and the rest of the physical sciences in general supports that it is perfectly plausible that it isn't inevitable.

    Also, I don't think that the fact that dinosaurs were around for millions of years without developing any kind of technological civilization necessarily supports that doing so isn't inevitable. On what basis do we determine what size of time spans are relevant for such a consideration? We have only one example so far, Earth's biosphere, and a technological civilization occurred here well within the life time of a viable biosphere on the planet.

    Now, I don't think that tells us much either as far as warranting any particular confidence in any conclusion about the incidence of intelligent, technological life in the universe. It suffers the same problem. Lack of data, namely a sample of one and the vast silence so far (as far as we can tell right now). But I don't think the fact that dinosaurs didn't achieve a technological civilization during their dominant eras means anything about the incidence of intelligence in the universe or its inevitability once life gets started somewhere.

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    Quote Originally Posted by Ross 54 View Post
    Given the long time span involved, it seems possible that any evidence of a civilization created by advanced dinosaurs would have been destroyed by materials decay or buried so well by geological processes that we would be unlikely to find it.
    Well, we find extensive examples of their fossilized bones, eggs, even imprints from feathers. So some kinds of technological evidence could easily have been erased, but I think if they had made extensive use of, say, refined metals, we'd see examples. I think even worked stone tools (like these, for example) would probably survive just as well as fossilized bone.
    Conserve energy. Commute with the Hamiltonian.

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    Maybe we'll eventually discover an ancient long abandoned dino-moon base alpha on the moon ;-)

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    Quote Originally Posted by Grey View Post
    Originally Posted by Ross 54
    Given the long time span involved, it seems possible that any evidence of a civilization created by advanced dinosaurs would have been destroyed by materials decay or buried so well by geological processes that we would be unlikely to find it.
    Well, we find extensive examples of their fossilized bones, eggs, even imprints from feathers. So some kinds of technological evidence could easily have been erased, but I think if they had made extensive use of, say, refined metals, we'd see examples. I think even worked stone tools (like these, for example) would probably survive just as well as fossilized bone.
    There is also no evidence that any species of dinosaur had the brain development for such intelligence.
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    The article, linked below, explores the possibility that evidence of a supposed dinosaur civilization, or of dinosaurs brainy enough to make a civilization could be elusive, even to the extent that we have not uncovered it yet. Even stone artifacts could undergo enough damage to render their artificiality less than obvious.

    strangehorizons.com/non-fiction/articles/was-there-ever-a-dinosaur-civilization/

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    Quote Originally Posted by Swift View Post
    There is also no evidence that any species of dinosaur had the brain development for such intelligence.
    The same could be said about most of my relatives.

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    Quote Originally Posted by Ross 54 View Post
    The article, linked below, explores the possibility that evidence of a supposed dinosaur civilization, or of dinosaurs brainy enough to make a civilization could be elusive, even to the extent that we have not uncovered it yet. Even stone artifacts could undergo enough damage to render their artificiality less than obvious.

    strangehorizons.com/non-fiction/articles/was-there-ever-a-dinosaur-civilization/
    Thanks for the link – very interesting article. Apart from the point that there may have been brainy dinosaurs whose fossils we haven't yet found, it also mentions the troodon genus of dinosaur, which had long arm-like front limbs, and seem to have been closer to birds than to lizards in terms of intelligence. The known troodons might (conceivably) have had even smarter relatives whose fossils we'll find in the future. If they had no such relatives by the time the great extinction event happened, another question is how they might have evolved if there had been no such extinction event.

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    I've stated many times that IMO there's no Fermi "paradox" to explain... the sheer size of space and the problems involved with spreading sentient colonizers across the universe explain the absence of aliens just fine.

    The FP is based on a large number of (unwarranted) assumptions*: That aliens exist near enough to reach us, that they have intelligence similar enough to ours to have advancing industrial civilizations, that they have interstellar travel, that they will colonize other stars, that they have had enough time available to spread to many/most stars in our galaxy, that they will have reached our star, that they will have a motive to visit us, that once having done so they will continue to hang around and colonize or leave incontrovertible evidence of their being here. And all the many supporting steps in between.

    ALL of those steps have to be assumed for Fermi to have his Paradox actually be paradoxical.


    * I'm giving the "life exists elsewhere" assumption a pass here.
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    I've stated many times that IMO there's no Fermi "paradox" to explain... the sheer size of space and the problems involved with spreading sentient colonizers across the universe explain the absence of aliens just fine.

    The FP is based on a large number of (unwarranted) assumptions*: That aliens exist near enough to reach us, that they have intelligence similar enough to ours to have advancing industrial civilizations, that they have interstellar travel, that they will colonize other stars, that they have had enough time available to spread to many/most stars in our galaxy, that they will have reached our star, that they will have a motive to visit us, that once having done so they will continue to hang around and colonize or leave incontrovertible evidence of their being here. And all the many supporting steps in between.

    ALL of those steps have to be assumed for Fermi to have his Paradox actually be paradoxical.


    * I'm giving the "life exists elsewhere" assumption a pass here.
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    Quote Originally Posted by Noclevername View Post
    I've stated many times that IMO there's no Fermi "paradox" to explain... the sheer size of space and the problems involved with spreading sentient colonizers across the universe explain the absence of aliens just fine.

    The FP is based on a large number of (unwarranted) assumptions*: That aliens exist near enough to reach us, that they have intelligence similar enough to ours to have advancing industrial civilizations, that they have interstellar travel, that they will colonize other stars, that they have had enough time available to spread to many/most stars in our galaxy, that they will have reached our star, that they will have a motive to visit us, that once having done so they will continue to hang around and colonize or leave incontrovertible evidence of their being here. And all the many supporting steps in between.

    ALL of those steps have to be assumed for Fermi to have his Paradox actually be paradoxical.


    * I'm giving the "life exists elsewhere" assumption a pass here.
    Funny, I was just about to make a thread asking about this paradoxical paradox - it`s been puzzling me for some time now - but the quote above encapsulates my thoughts very closely.

    Since I`m a near-total ignoramus when it comes to science I always have to assume that I`m probably wrong regarding such subjects. However, I would appreciate if more knowledgeable folks cleared this issue a bit. My main problem with FP is that it seems to be taken so seriously, whereas it seems more of an anecdote to me, or at best a lightweight proposal. That`s for reasons Noclevername already stated and also:

    -it stems from the assumption that we should be easily able to detect the ETs: what is this based on? To my best (worst knowledge serious SETI programs are a) very young b) fairly limited by technology vs sheer task size. And Mr Fermi stated it in the Sixties so even before the recent advancements.

    -to contact us aliens would have to detect us first and then we would have to detect their communication. Again, tech vs size problem. How advanced a technology would have to be to allow for this? I mean, assuming a civilization is beaming a reasonably strong signal toward Earth, what are our chances of detecting it?

    -what are our chances of detecting indirect alien activity in the galaxy - meaning not an actual message aimed at us? For example were there another civilization similar to ours technologically would we be able to pick up their radio - or other -footprint?

    -regarding interstellar travel itself, most of my concerns are mentioned by Noclevername...yet the Paradox assumes that "the Milky Way galaxy could be completely traversed in a few million years". It seems possible yet fairly unlikely (IMO, as always), given all the obstacles.

    -so far we concentrated on our galaxy: is there any way we could detect a civilization based in another galaxy given our current tech?

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    Quote Originally Posted by Gomar View Post
    Ok, so why then didnt Dinosaurs evolve to create high-tech? Given hundreds of millions of years of their existence, dinos should have developed space ships to either colonize the solar system, or even to fly to other habitable planets in order to avoid extinction caused by meteorites. Ifcourse, a few nukes could've solved that problem as well.

    My point is that dinosaurs went extinct allowing rise of homo sapiens. If alien planets have dinosaurs, the only way for primates to rise to our level is for a meteor to hit their planet.
    Otherwise, just as on Earth, dinos would still rule preventing other species from evolving.
    It's incredibly unlikely other planets would have dinosaurs or primates. Analogous organisms in analogous ecological niches, perhaps. I also think that, even were dinosaurs to have gotten to current technological levels, it would be incredibly difficult to find evidence of their civilization.

    Trying to get back to explanations for the Fermi paradox, I think the easiest ones are a) interstellar travel is much harder than all but the most pessimistic think, b) We're the most advanced technology within the galaxy and c) they checkup on Earth every 20,000,000 years, and we're not due for another 19 million.

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    Quote Originally Posted by Noclevername View Post
    I've stated many times that IMO there's no Fermi "paradox" to explain... the sheer size of space and the problems involved with spreading sentient colonizers across the universe explain the absence of aliens just fine.

    The FP is based on a large number of (unwarranted) assumptions*: That aliens exist near enough to reach us, that they have intelligence similar enough to ours to have advancing industrial civilizations, that they have interstellar travel, that they will colonize other stars, that they have had enough time available to spread to many/most stars in our galaxy, that they will have reached our star, that they will have a motive to visit us, that once having done so they will continue to hang around and colonize or leave incontrovertible evidence of their being here. And all the many supporting steps in between.

    ALL of those steps have to be assumed for Fermi to have his Paradox actually be paradoxical.


    * I'm giving the "life exists elsewhere" assumption a pass here.
    One should really speak of the "Fermi-Hart paradox". Or the "Fermi-Hart question", if you think the word paradox is inappropriate. Fermi made a remark based on some quick calculations. Michael Hart published a paper in a journal about why the question should be taken seriously. The "assumptions" are basically two:

    1. Comparable forms of life are likely to appear on comparable planets.
    2. Interstellar colonisation will be feasible and attractive to our descendants.

    The point is not that we know these propositions to be true, but that they are plausible enough to consider what the consequences would be if they were true. In fact, Hart argues that they cannot both be true, since otherwise Earth would have been colonised already by beings comparable to humans, who evolved on a planet comparable to Earth, but (in geological terms) just slightly older.

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    Quote Originally Posted by akeley View Post
    Funny, I was just about to make a thread asking about this paradoxical paradox - it`s been puzzling me for some time now - but the quote above encapsulates my thoughts very closely.

    Since I`m a near-total ignoramus when it comes to science I always have to assume that I`m probably wrong regarding such subjects. However, I would appreciate if more knowledgeable folks cleared this issue a bit. My main problem with FP is that it seems to be taken so seriously, whereas it seems more of an anecdote to me, or at best a lightweight proposal. That`s for reasons Noclevername already stated and also:

    -it stems from the assumption that we should be easily able to detect the ETs: what is this based on? To my best (worst knowledge serious SETI programs are a) very young b) fairly limited by technology vs sheer task size. And Mr Fermi stated it in the Sixties so even before the recent advancements.
    Agreed. As recently as the early 1930s, within living memory, radio detection beyond our atmosphere was unknown.

    -to contact us aliens would have to detect us first and then we would have to detect their communication. Again, tech vs size problem. How advanced a technology would have to be to allow for this? I mean, assuming a civilization is beaming a reasonably strong signal toward Earth, what are our chances of detecting it?
    Sending a strong coherent signal across several light years is a nontrivial but not unsolvable problem. Assuming it is meant to be detected, our current radio astronomy may be able to find a close source. As you get further away, detection becomes more problematic with intervening gas, dust, stars, plasma, and other natural radio sources adding to the background noise.


    -what are our chances of detecting indirect alien activity in the galaxy - meaning not an actual message aimed at us? For example were there another civilization similar to ours technologically would we be able to pick up their radio - or other -footprint?
    If Earth's current radio emissions were at the nearest star, Proxima Centauri, then using our present day technology we would not be able to hear ourselves.


    regarding interstellar travel itself, most of my concerns are mentioned by Noclevername...yet the Paradox assumes that "the Milky Way galaxy could be completely traversed in a few million years". It seems possible yet fairly unlikely (IMO, as always), given all the obstacles.
    It could be... hypothetically, if an advanced civilization made rapid expansion to all places the driving goal of their society (and kept that drive for millions of years). To my mind it's a "possible but not plausible" scenario.


    -so far we concentrated on our galaxy: is there any way we could detect a civilization based in another galaxy given our current tech?
    There are ways, again possible but not at all likely for many reasons. There was a recent attempt to find a "Kardashev III" civilization, which had (hypothetically) energy collecting Dyson Spheres around all stars in a galaxy. None were detected. A Dyson Sphere'd star or ten, used to power a transmitter might send a laser signal that could possibly make it between nearby galaxies and still hold an understandable signal... or might not. Too many unknowns to say for certain. Other means may exist, but they're pure blue-sky guesswork.
    Last edited by Noclevername; 2017-Jan-16 at 09:01 PM.
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    VanNeumann probes which are also Bracewell probes are what I am thinking of. Making a probe traveling 10% the speed of light is not absurdly beyond our foreseeable technology. To make it self-reproducing would require it to have the capabilities of a bacterium, a plausible capability for a star probe launching society.
    Everything we have sent beyond the orbit of Saturn has been a kind of crude Bracewell probe...the Pioneer plaque, the Voyager record and the New Horizons message.
    Personally, I think that the odds of getting a proto-bacterium able to reproduce and evolve out of lifeless matter is astronomically unlikely.
    But I could be wrong.

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    Quote Originally Posted by Tom Mazanec View Post
    VanNeumann probes which are also Bracewell probes are what I am thinking of. Making a probe traveling 10% the speed of light is not absurdly beyond our foreseeable technology. To make it self-reproducing would require it to have the capabilities of a bacterium, a plausible capability for a star probe launching society.
    Everything we have sent beyond the orbit of Saturn has been a kind of crude Bracewell probe...the Pioneer plaque, the Voyager record and the New Horizons message.
    Personally, I think that the odds of getting a proto-bacterium able to reproduce and evolve out of lifeless matter is astronomically unlikely.
    But I could be wrong.
    Self replicating Von Neumann probes could potentially cover the Galaxy... but then what? Returning viable information to their point of origin means informing the great-to the-Nth-power grandchildren of their makers, GNchildren who might very well have evolved into another species, or gone extinct, or developed an 11%-of-C drive and moved ahead of the former probes.

    So I can't see any viable purpose for spreading to the entire galaxy.
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    Quote Originally Posted by Tom Mazanec View Post
    VanNeumann probes which are also Bracewell probes are what I am thinking of. Making a probe traveling 10% the speed of light is not absurdly beyond our foreseeable technology. To make it self-reproducing would require it to have the capabilities of a bacterium, a plausible capability for a star probe launching society.
    Everything we have sent beyond the orbit of Saturn has been a kind of crude Bracewell probe...the Pioneer plaque, the Voyager record and the New Horizons message.
    A Bracewell probe, i.e. a probe designed to communicate with other civilisations, is an interesting concept... but apart from the cost of send out the probes, such a project would get the same objections as projects to send out radio messages. Some would argue that it isn't sensible to advertise our presence to beings whose intentions and capabilities are unknown to us...

    Personally, I think that the odds of getting a proto-bacterium able to reproduce and evolve out of lifeless matter is astronomically unlikely.
    But I could be wrong.
    Getting that result by pure chance would indeed be astronomically unlikely... But in a chemical system which is far from equilibrium, in which there are simple molecules which catalyse their own formation (autocatalysts), there is a dynamic at work which is not pure chance...
    Last edited by Colin Robinson; 2017-Jan-17 at 06:57 PM.

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    I don't know the probability of life forming, evolving intelligence, developing technology, deciding to send out interstellar probes or signals, and doing so in a time frame where they would be detectable to us would be. Even assuming the first four, it's probably only the past 65 years or so we had any chance of detecting an interstellar radio signal and only the past two hundred or so of detecting an interstellar vehicle passing through. We're also not looking very hard.

    So far all we have got is a null result after a search roughly analogous in effort to looking for your lost keys in the left pocket of your favorite jeans.

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