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Alone in a Crowded Milky Way

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• rainworld 7y ago
  More likely we really are alone: http://aleph.se/andart2/space/seti/dissolving-the-fermi-paradox/ http://aleph.se/andart2/space/seti/dissolving-the-fermi-para...
  • bagacrap 7y ago
    That paper only claims that it is plausible we're alone, meaning the Fermi paradox is only a question, not a conundrum.
• dade_ 7y ago
  I find it strange that the author thinks that Dark Forest theory is implausible. It strikes me as the simplest of explanations. Granted Cixin Liu stretches physics into all sorts of implausible places, but it does make a strong argument for the theory. https://www.goodreads.com/book/show/48838110-three-body-problem-boxed-set?ac=1&from_search=true&qid=cqWNAtigNA&rank=1 https://www.goodreads.com/book/show/48838110-three-body-prob...
  • gilbetron 7y ago
    I loved the series, but the physics was horrendous, and I don't agree it made a strong argument for the Dark Forest theory. It made an enjoyable, interesting read about the Dark Forest theory, but the schemes the author used didn't make sense and wouldn't result in the universe as described in the books.
    • fsloth 7y ago
      Yeah, the book was about allegories and situations. The plot devices were intended to drive certain plot elements, not to be in the Clarkean way the first principle driving rationale for the work. The trilogy is very enjoyable!
      • gilbetron 7y ago
        Well put - the way he wrote the "science" was fun and used in novel, clever ways to further the interesting situations and ideas and analogies, which is why it was awesome. Plus it was neat reading a book that was first Chinese and then translated. I found the subtle differences in tones and characters fascinating.
  • fsloth 7y ago
    The dark forest theory works wonderfully as a plot device in the book. That trilogy is the best sci-fi I've read after Banks, Clarke and Asimov, hands down. But, if you stop and think about it, in the real universe it has two gaping problems: First, The Dark Forest theory depends on the capability and willingness to develop world destroying devices. Second, it depends on the likelihood that the species you detect has not yet spread to other systems. If it has, congratulations, you have started a shooting war with an enemy whose threat level you have no gauge of. Some with an inclination of game theory might want to figure this out through better, though.
    • creato 7y ago
      > First, The Dark Forest theory depends on the capability and willingness to develop world destroying devices. Any civilization capable of traveling to another solar system has this capability: just take one of their ships designed to accelerate to significant fractions of the speed of light and decelerate at the other end of the journey, set a course, and simply don't decelerate. > Second, it depends on the likelihood that the species you detect has not yet spread to other systems. If it has, congratulations, you have started a shooting war with an enemy whose threat level you have no gauge of. Some with an inclination of game theory might want to figure this out through better, though. There's a good chance the above described weapon would be nearly undetectable and untraceable. For at least the latter half of its journey, it's just a chunk of mass traveling through space, emitting no signals. It would also be only a small factor difference in capability (0-1 more accelerations and decelerations than an actual interstellar transit) to send it from a different part of the galaxy.
  • detritus 7y ago
    Another book in this vein, although distinctly more uncompromising in its conclusion, is The Killing Star, by Charles R. Pellegrino and George Zebrowski.
    • hindsightbias 7y ago
      Available on Audible now. Hard to find it in print. Another series is Greg Bear’s Forge of God
    • detritus 7y ago
      Having just today finished Cixin Liu's 'Death's End', I rescind my 'distinctly more uncompromising' comment.
  • jmull 7y ago
    I loved those books, but the dark forest theory doesn’t make sense. Given a dangerous universe it would make sense for a civilization to try to communicate with other civilizations to create alliances for mutual safety. The civilizations that are able to forge alliances will tend to out-compete lone wolves. Liu assumes that it is somehow a lot easier to wipe out a civilization than communicate with it, and that for some reason your civilization has to decide to wipe out another civilization without communicating with it.
    • LoSboccacc 7y ago
      alliances put some lower bound constraint on the logistic capabilities and density of the civilisations that form them. strategically speaking and stunning hostile unknowns a stable civilization controls a territory matching reasonable response time from the ready armies at their combat speed and necessarily a requirement for alliances to form is for these zones to overlap but if they are at such distance it negates one of the prerequisite for the dark forest theory, that civs are sparse enough for the chance of facing hostiles alone is on par with encountering non hostile civs
      • krapp 7y ago
        Interstellar space isn't an ocean, and star systems aren't countries. Analogies to Earth militaries and navies simply don't apply, the scale of space is too big. You're not going to form any sort of "alliance" over a distance of light-years, much less consider the fleets of hostile civilizations to be a threat by their proximity the way England once considered Spanish fleets a threat. There's no "reasonable response time" when allies will take years to hear your distress call, and more years to arrive.
    • ceejayoz 7y ago
      > Liu assumes that it is somehow a lot easier to wipe out a civilization than communicate with it... This may be true, though. We struggle to effectively communicate with creatures on our own planet available in real-time, like dolphins and elephants, who appear to think and have language of sorts. Launching some relativistic sand at another planet may well be a lot easier.
• ryanSrich 7y ago
  The article does a good job of explaining some of the numbers, but it’s important to remember just how large they are. To a spacefaring civilization a million years might be the human equivalent of a decade. The sad truth is that intelligent humans (enough to think and act on thoughts of space travel) have barely existed on the cosmic timeline, and likely won’t live long enough to know the answer to whether or not we’re alone. Not because of some romanticized fermi gate paradoxical reasoning, but simply because we ran out of time.
  • lonelappde 7y ago
    What do you mean? How is running out of time different from a Fermi gate? Without a gate, why would time run out? The only natural limits are the time limit to colonize another planet, then another solar system, before our earth and sun lose their ability to sustain life.
• smallstepforman 7y ago
  Well, even if we're not alone, we must acknowledge that someone had to be first to develop the ability to travel through the cosmos. It may actually be us.
  • bagacrap 7y ago
    I'd like to think it's at least possible that a life form which made it to the stars without blowing itself up is compassionate enough to leave Earth the heck alone and treat this system as a giant nature reserve. Perhaps they'll swoop in and borrow our tech if we ever come up with anything good, just as we might draw on the natural world for new medicines or construction materials.
    • krapp 7y ago
      You're assuming a species that practices "compassion" towards its own kind would care about us. Human history is full of examples of societies which treated their kin with kindness, but others with cruelty.
      • gfodor 7y ago
        And yet, over time, humanity has trended to respecting the life of all sentient creatures. It seems like in the limit, especially if scarcity of resources is eliminated, all life will be precious and valued.
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        • perl4ever 7y ago
          I just googled for how many lab animals are used in reseach in the US, and the number was ~800K in 2017. But (and this is a big but) rats and mice (and birds and fish) are not counted. For some reason, guinea pigs and hamsters are considered more equal than rats and mice. One supplier of lab mice in Maine provides ~3 million mice per year... Yearly production (and slaughter) of chickens is something like 60+ billion. Not sure if sentient, but perhaps they deserve it as descendants of the dinosaurs that terrorized human ancestors...
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• ohazi 7y ago
  I don't buy this argument. Let's pretend for a moment that there are currently 5-20 intelligent species in our galaxy, and everyone except us developed deep space ships and successfully colonized thousands of other planets (make up almost any numbers you want here; the results still hold). What would our telescopes see? It seems like we would most likely see exactly what we see today. The probability that one of those ships happened to fly anywhere close to our solar system, while we were looking, is still vanishingly small. Omnidirectional radio transmissions spread so quickly that they fall below the noise floor almost instantly over interstellar distances. Space is really really really really big. We can see stars. We can just barely see some planets in a few very specific configurations. We can sometimes make coarse estimates of the chemical composition of those planets. And that's about it. We don't really know how to detect life on extrasolar planets. The ones we've already found could be teeming with life and we wouldn't know it.
  • phkahler 7y ago
    For a simple example, can anyone see Elons Tesla Roadster out near Mars? And that's something we know is there.
    • ianai 7y ago
      https://www.whereisroadster.com/ https://www.whereisroadster.com/ “A telescope about 51,075 ft (15,568 m) in diameter would be required to resolve the Upper stage from Earth. A smaller one could see him as an unresolved dot, about 98.2 ft (29.9 m) in diameter, in ideal conditions” So I recon that reinforces the hypothesis.
      • aruggirello 7y ago
        Not necessarily, the apparent magnitude is the issue here, not resolving power. Located at a comparable distance, Deimos, the smaller moon of Mars, reaches at most magnitude ~12.5, meaning that any telescopes smaller than 6" to 8" might not even be able to ever detect it's there. And we're talking about a 6.2Km sized moon, not an object with an overall visible area ~40000 times smaller - that would mean an apparent magnitude of ~23-24 as seen from Earth, meaning only the most powerful telescopes on Earth would be barely able to detect that "unresolved dot" - provided it had the same albedo of Deimos. https://en.wikipedia.org/wiki/Deimos_(moon) https://en.wikipedia.org/wiki/Deimos_(moon) https://en.wikipedia.org/wiki/Apparent_magnitude https://en.wikipedia.org/wiki/Apparent_magnitude Edit: corrected
• papito 7y ago
  I think it's time we stop looking for life near other stars and start saving our own. This planet is completely neglected. You want to live on Mars? That should be fun, without a magnetic core. Living underground, like rats. If you want to know what frontier living feels like, take a week off and stay in one of the Inupiat villages on the edges of Alaska. You'll be climbing up walls in 3 days. And that is a luxurious vacation compared to frontier living on a barely habitable planet. Netflix? Nah, bro. They still have Blockbuster.
• zw123456 7y ago
  I have a somewhat nihilistic theory around the Fermi paradox. What if all intelligent life annihilates itself before reaching high enough technical proficiency to achieve widespread inter-planetary travel (or time travel). The idea is that intelligent life emerges from the process of evolution (natural selection) where the stronger survive. But that leaves you with people who have the tendency to kill each other and themselves off. As the technological ability to completely annihilate ourselves increases the probability that it will eventually happen goes up over time. As technological prowess increases and population increases, intelligent species eventually destroy themselves by using up all their resources or ruin the planet with climate destruction before achieving inter-planetary capability. Similar to how yeast will reproduce until they all kill themselves off in their own waste product (alcohol). It is possible that this is a universal axiom, hence intelligent life does not spread across the galaxy. I know this is a depressing thought but it's an idea that has haunted me once it occurred to me.
  • typon 7y ago
    This is known as the Great Filter theory
    • zw123456 7y ago
      oh thanks, just googled it, I had not heard of it.
      • sethd 7y ago
        It’s described in the article: > Sounding a more ominous note are concepts such as the “great filter”—the idea that there is something that always limits a species, perhaps an inevitable failure to achieve that green revolution, leading to an implosive extinction of all potentially technological life.
  • hesdeadjim 7y ago
    The models attempt to encapsulate this issue through the variable of how long a civilization lasts. As easy as it is to imagine civilizations similar to us, it’s equally easy to imagine others where other variables prevent the intense egoism we evolved as a species. Or worlds where competition is less fierce perhaps. Etc.. Either way I find it fascinating that we could be living in what is essentially the rural area of the galaxy.
• johnwheeler 7y ago
  I think if you look at patterns in nature this has to be possible. Surely there are some remote ant colonies that don’t have interaction with anything outside the natural resources that sustain them.
• mouzogu 7y ago
  My theory is that any advanced civilisation reaches a point at which a vast amount of destructive power becomes accessible to individuals. At this point it becomes only matter of time until that civilisation is destroyed. The analogy I use is to imagine that every adult human on Earth woke up tomorrow morning with a button on their wrist that could destroy the Earth. How long do you think we would last? We haven't reached a stage where an individual can create a nuclear bomb, a new kind of super-virus or some other doomsday weapon but I imagine its not an implausible scenario in the future. I think this is kind of a wall that all advanced civilisation may hit at some point.
  • qw 7y ago
    If that happened you would probably see (wealthy) people migrating to underground bunkers to protect themselves and interact using VR. That could be one of the explanations why they don't go out to create colonies and make enough noise for us to detect them.
  • gfodor 7y ago
    This is an interesting theory I have considered as well, however there is a reason to disbelieve it. It assumes at its core the diffusion of some form of highly destructive technology, and that the technology will be unleashed in an irreversible way before it can be recognized and “put back in the box”, or it can’t be “put back in the box”. These assumptions individually seem strong but together they get quite weak. For example, diffusion of civilization over several planets before this technology is diffused provides a potential firewall. (For example, once the technology is recognized, an orderly exodus is made which forcibly leaves behind any trace of it.) Alternatively, the diffusion itself may not occur as well, similar to the current life-ending technologies we have now that can only be created by state actors. It is a legitimate prospect — but hinges upon several aspects hung together to get to a point where it’s an inductive invariant explaining fermi.
    • NortySpock 7y ago
      Maybe a biological weapon being unleashed from some genocidal nutcase's basement hobby laboratory?
• chmike 7y ago
  I don't understand why ufological data is systematically ignored. This leads to biased reasoning.
  • gfodor 7y ago
    Indeed, if this theory is correct what we should expect to see are individual, small expedition-like visitations, which aligns roughly with the limited bits of credible ufo-related data.
  • revscat 7y ago
    I wouldn’t say it is ignored, more that it isn’t particularly useful. Shaky YouTube videos don’t allow for much in the way of study. Even more convincing sources, such as that video released last year of the Tic Tac UFO, were interesting, but not all that useful.
  • plutonorm 7y ago
    I agree. To talk about the possibility is to commit scientific suicide. Even cautiously talking about the topic immediately outs you to others as a crackpot. I think it's undeserved. Especially when we are now seeing just how many habitable world's are out there. It seems plausible that we have been visited by curious extra terrestrial civilisations. The bizare patents coming out of the US navy suggest to me that no one knows where these things are coming from, if they are real.
    • anthonypasq 7y ago
      > It seems plausible that we have been visited by curious extra terrestrial civilisations. no it doesnt. It seems increasingly implausible
      • chmike 7y ago
        How do you justify this claim ?
  • zokula 7y ago
    One would have to assume that UFOs are piloted by aliens which since there is no proof alien life exists it's a Fool's errand.
• archeantus 7y ago
  It seems to me that the millions of events that happened in order to get to where we are now (alive on a rocky, water and oxygen-filled planet, in the Goldilocks zone of a healthy star) were sequential in nature and they took a finite amount of time to occur. Assuming that there was A Beginning, where everything started at the same time, wouldn’t the steps to get to where we are in this process take about the same time for everyone else? Meaning that if there are other civilizations out there, that they’d more or less be as advanced as we are? Which is pretty sophisticated in certain areas at home, but not yet super capable in the long-distance human space travel department. Not a scientist, just thinking out loud the thought I had reading the article.
  • MattRix 7y ago
    There are many stars and planets much much older than ours. Earth is 4.5 billion years old, the oldest exoplanet we've seen is 12.8 billion. The terms of the Fermi paradox are are designed to cover things like this.
  • IAmGraydon 7y ago
    Perhaps, but even tiny variances could cause shifts in the timeline of thousands or millions of years, which would be a blink compared to the age of the universe. Look how far we’ve come in the last 200 years. Imagine a civilization that is only 10,000 years ahead of us.
    • archeantus 7y ago
      I’d love to see what the iPhone 10,000 ends up looking like
  • peteradio 7y ago
    50000 years ago we were throwing chipped rocks at hairy elephants. Technology moves fast on galactic time scales. Expecting two alien species to have roughly the same tech would be like two randomly fired bullets to collide mid air.
• bmdavi3 7y ago
  Does a lion born in a zoo understand it's being held captive by (in comparison) super intelligent humans? When it's tranquilized, does it know this isn't a normal thing for a lion? When the caretaker throws food out or pets it, does the lion have the capacity to think about it in any other way than what it means right now for the lion - food, feels nice, etc? If there's a correspondingly more intelligent alien species hanging out on our planet with us, would / could we even hope to know?
  • lifeisstillgood 7y ago
    yes. Edit: Ok. This is a common argument (well apart from the "living on earth with us" bit which requires some Doctor Who levels of mind-wiping so let's discount that. Lions see humans in the zoo, and they see the walls of theie prison. Lions definitely have had psychological problems in the worst run zoos so it is fair to say they are affected and aware. Are they aware of the concept of zoo? Equally unlikely. And the next question is how much more intelligent is a human to a lion. the answer is not comforting to us as a species.
    • bmdavi3 7y ago
      I'm not sure where the corresponding boundary would be exactly, since we do seem to be on the verge of exploring other planets, but you could say that we also understand where it is we're allowed to roam - the surface of Earth. And we aren't free of psychological problems.
  • nsomaru 7y ago
    Interesting philosophical proposition, have an upvote. It also speaks to the limitations of our senses and the way we experience the world.
  • lordnacho 7y ago
    But Lions don't appear to have any abstraction ability, or reflective thought. By that I mean you as a human can imagine yourself thinking about some hypothetical situation, as well as consider what kind of evidence would support a given hypothesis. I think this might have actually happened (apocryphal?), but just imagine if you took humans from another country and put them in a zoo. They would surely figure it out, based on the evidence at hand.
• lifeisstillgood 7y ago
  I would be especially careful of arguments that end up like "it's a great opportunity for humankind as no-one else is there to compete for the next million years" It might be true. But the most likely thing we will find on the nearest habitable planet is a legal writ and summons.
• BerislavLopac 7y ago
  I personally subscribe to the school of thought that interstellar travel is impossible, except through some form of suspended animation or generation ships (which both have its own problems). So no warp/hyperdrives, no wormholes, no shortcuts to travel between the stars. This article dismisses that notion before it even begins, but this is the only theory that fits the currently observed laws of the universe.
  • m4rtink 7y ago
    Even with no FTL, you can still do interstellar travel just fine if you make people live longer, which is being worked on for other reasons already.
    • jcranmer 7y ago
      It's not individual lifespans that are the issue, it's the lifespan of your equipment. If your rocket breaks down in the interstellar void, you have no resources with which to fix it. And then you need to be able to bootstrap the entire industrial base to build a new rocket at your destination without any help whatsoever aside from what you brought with you. Given the history of interoceanic colonization efforts on Earth, this suggests that the difficulty ranges from "insane" to "impossible."
      • m4rtink 7y ago
        I think thats stil managable, even simply by redundancy and sending fleets of ships. Also 3D printing of replacement parts seems pretty promissing and is already being looked into (there is a basic 3D printer or the ISS).
        • tptacek 7y ago
          There is, but it doesn't really do anything, right? They printed some plastic toys with it; it's not operations-critical.
  • zzzeek 7y ago
• j_m_b 7y ago
  The theory of this article is that we are not just in a gulf of space but also a gulf of time. We are after all on the relative outskirts of our galaxy, vastly isolated from other civilizations. Perhaps one day we'll be the ones knocking on our neighbor's door to say hello!
• bena 7y ago
  Fermi paradox. I never liked it. It presumes too much. It presumes that technology will advance to the degree that we overcome the speed of light. Not directly, but that's where it has to wind up. Because no matter how you slice it, it's still four years to Alpha Centauri at the fastest possible speed we know. That means it will be at a minimum 8 years before we know if anything was successful. And yes, for the travelers, they experience time dilation, but we here on Earth would not. That time does matter. Even with self-replicating Von Neumann probes, they still have to send that information back. That's still going to take time. How many resources can you dedicate to a bet that's going to take at least a decade to show a return? How many of those bets can you make before you've depleted your resources to the degree that you simply cannot do it anymore? I think we may find ourselves up against the uncomfortable truth that our cosmic range is rather limited.
  • m4rtink 7y ago
    IIRC Fermi paradox does not expect FTL - a locust style colonization effort should be able to settle the whole milky way quite quickly (couple hundred thousand years) even with not very fas sub light travel.
    • bena 7y ago
      Like I said, not directly, it doesn't, but once you start digging down, you're going to need that. A couple hundred thousand years is quick on a cosmic scale, but we, as a species, have never undertaken any project on that scale ever. No species has that we have evidence of. Any sublight travel is a one way trip with almost no hope of ever knowing it was a success by the people back home. No one funds that. And I don't blame them. There is no return in any fashion for the people who remain. And little to no return for anyone who starts the journey. The only thing you can possibly satisfy is some minor curiosity. Travel to Proxima Centauri at the current highest speed we've sent probes into space would take over 80,000 years. If you double that speed. It will still take over 40,000 years. So, cosmically, the time scale is short. And compared to light, the speed needed is slow. But we're not light, are we? We don't exist on cosmic scales. I'm not concerned with the theoretical limits of physics. I'm more concerned with the practical limits of us.
• stevev 7y ago
  I am intrigued by the simulation theory. That we as a species has reached a certain level of advancement to simulate a reality and experience it; or we may just be npcs or temporary programs for another intelligent race in this simulation. We could also be a zoo/prison planet far into enemy territory. Currently being experimented and observed. Hybridization in order to infiltrate our actual civilization that’s located elsewhere.
• carapace 7y ago
  Fascinating theory, but we aren't Pitcairn Island. > Why, then, have we found no irrefutable evidence of aliens visiting Earth? We have evidence, it just gets "refuted" for psychological reasons. The Fermi Paradox is a Rorschach test, and has nothing to do with reality. In reality, humans in every culture have recorded incidents of communications with non-human intelligences.[0] In reality, the Brazilian Military has gotten much less coy about UFO phenomenon in recent years and has started declassifying documents. Their overall conclusion is that, whatever they are, UFOs are real, pose no national security threat, and should be researched and discussed by society at large, with some urgency. Here's a fascinating lecture by a Brazilian UFO researcher about the overall situation in Brazil and he describes three encounters that are known to have government involvement (so the researchers know what to ask about, in these cases.) "Operation Saucer - UFO military encounters in the Brazilian jungle" https://www.youtube.com/watch?v=ThkmRsEBOY0 https://www.youtube.com/watch?v=ThkmRsEBOY0 > In 1977, numerous UFOs were seen in the Brazilian city of Colares, Pará. The UFOs fired light beams at people, causing injuries and sucking blood from 400 witnesses. After a rise in local concern, the mayor of the city requested help from the Air Force. Operation Saucer started, during which numerous photos were taken and testimonies collected. Operation Saucer is just one of the compelling cases which A. J. Gevaerd, editor of Brazilian UFO magazine, talked about in his latest lecture in Copenhagen, paving the way for complete Disclosure in his country. Kudos to Exopolitics Denmark for setting up their excellent annual conference at the Danish National Museum on September 26 in Copenhagen! The first case involves thousands of people, living on an island in the Amazon, who were attacked by UFOs over a period of several years (1975-1977 IIRC). Flying cans with visible pilots were shooting people with bending "light" beams and sucking up their blood. It got so bad that thousands of people evacuated and the Brazilian Army sent in a unit to find out what was going on and try to make contact. I won't spoil the rest of the story here. To me, the strangest thing I can see is the question: Why would people (aliens or humans) who have evidently advanced technology go around attacking poor villagers to suck their blood!? WTF? [0] (I myself once attended a event at an airport hotel at which some purple telepathic space dolphins were guest lecturers. FWIW, their basic TL;DR: was "Be nice to each other." Aliens were attending underground raves in Seattle in the 90's.)
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• CuriousReader13 7y ago
  What’s the point of settling on planets if you can sustainably develop anywhere in space, which I think is within the reach of any typical space-faring civilization?
  • m4rtink 7y ago
    I guess, you can do both. Well unless you want to use the mass of the planet for a more efficint purpose, eq. habitat swarm.
• hindsightbias 7y ago
  Afaik, nobody has debunked the Borra paper, so we already found them. Discovery of peculiar periodic spectral modulations in a small fraction of solar type stars https://arxiv.org/abs/1610.03031 https://arxiv.org/abs/1610.03031
  • tokai 7y ago
    This study fails to replicate Borra's results. https://iopscience.iop.org/article/10.1088/1538-3873/aaeae0/meta https://iopscience.iop.org/article/10.1088/1538-3873/aaeae0/...
    • hindsightbias 7y ago
      Drat! Thanks
• Magi604 7y ago
  Perhaps slightly off topic, but the title reminded me of this picture I took a few years back. https://www.flickr.com/photos/earlvontapia/16211171391 https://www.flickr.com/photos/earlvontapia/16211171391 I really wanted more of the Milky Way to pop out, but was hard given the sensor and the lens I was using.
• yibg 7y ago
  The problem with these types of arguments is they are assumptions built on top of other assumptions. We don’t know how to colonize other star systems, so we don’t really know the factors at play. How easy is it to travel to another planet and start a colony? We don’t know. How likely is it that that colony will colonize other planets? We don’t know. We are taking numbers we guessed and multiplying with other numbers we guessed to get to an answer. If any of them are much off the answer doesn’t make sense? What if the amount of resources to successfully travel to and colonize a planet in another solar system is so high that the vast majority of attempts fail and only a few attempts can be made? We can have n (pick some random large number) intelligent civilizations in our galaxy and not know a thing about them.
  • DubiousPusher 7y ago
    My thoughts exactly. I've always found it funny how people imply there's some major issue with cosmology because the Drake equation shows there should be intelligent life all over. Even though some of the terms in that equation are very not known and it would only take a few being an order of magnitude or two smaller than expected to result in a paucity of intelligent life rather than an abundance.
    • yibg 7y ago
      Right. The Drake equation was never supposed to "show" anything. I think the original intent was to lay out the factors at play and stimulate conversation, not to provide a probability. I think over time, the imagination of the public have taken over though and put more confidence behind things than we should.
• ws66 7y ago
  One thing I fail to see mentioned here and in such articles is the complexity of colonization. We are falling in the trap of "idea == profit". A lot needs to be done, and can go wrong, between both. Some examples I am thinking of, and I am certain people will have more... All are compounded by the LY distances between colonies and whatever home is: - Terraforming - It would be the exception that new planets are 100% hospitable to a specific species. How long to properly terraform, and then how long before the can get to a point where they can launch a new sub-colony? Need proper population, technology and resources. - Culture drift - how long can the colony and home share the same culture, with same values and objectives? - Political drift - Imagine you are part of a colony, with "home" some 4 LY away. How long before you will want to have full autonomy, specially given the distance? - Cultural and political factions - Is it possible that individuals in the colony have different objectives, resulting with political infighting or open war? What would then be the impact on the colony? - Protection - Depending on technological advancement, how can a colony protect itself from external rogue elements (big warship gone rogue, pirating the colonies for resources?) For sure, many of these things depend on the type of species colonizing its region, how much sentience and free will they have. I also assume they haven't solved FTL travel!
• jajag 7y ago
  Previous discussion on the possibility (mentioned in the article) that an advanced industrial civilization existed on Earth: https://news.ycombinator.com/item?id=21840320 https://news.ycombinator.com/item?id=21840320
• graycat 7y ago
  (1) Biological life colonizing other planets? The individual beings would not live long enough to make the journey. So, would have to have reproduction of generations during the trip, and that means one heck of a big spaceship. Then for any of the motivations, I would be easier just to stay home. (2) Sending self-reproducing robots? Why? What's the motivation? E.g., why should I consent to spending big tax bucks to send robots out that would need millions of years to have any effect back on earth? I won't. Okay, there is the scenario that a planet is ready to die, and the beings want to move to a new land. Again, for anyone alive, what is their motivation? That is, either stay home and wait for, say, the star to nova or just die on a long space trip? Just stay home; as bad as a star nova would be, just stay home. One more scenario is that fast space travel is possible but uses physics we don't understand and, thus, can't detect.
• rm445 7y ago
  Discussions of the Fermi paradox get swamped with people's individual hypotheses. It's nice to see an article that tries to develop a whole different kind of answer. The known possibilities seem to be: 1. We're alone (or very nearly so) due to an early filter. i.e. it was vanishingly unlikely for life to develop as far as it has here. 2. We're alone (or very nearly so) due to a late filter. i.e. life develops in lots of places but, terrifyingly, it becomes overwhelmingly likely to wipe itself out rather than spread. 3. Life develops frequently but there's some sort of interstellar ecology that makes species stay hidden or be wiped out. 4. Life develops frequently but is overwhelmingly likely to develop some other interest (becoming inward-looking, or exploring other dimensions) rather than colonising all of space. This article's suggestion that Earth may be in a backwater wouldn't be sufficient by itself, so it is coupled with the idea, derived from observations on human colonisation of Micronesia, that expansion happens in waves and life on Earth happens to be in between waves. The problem is, advanced technological civilisations expanding across the galaxy isn't the same thing as Polynesian explorers eventually being followed by Europeans. Why would the waves die away? This is a late filter with extra steps.
  • 8bitsrule 7y ago
    5. No Aladdin's lamp. There's no FLT, no wormholes, no solution to the huge distances. And/or interstellar space is so full of toxins or plasmas no lifeform can survive it. And/or all EM data transmissions are reduced/scrambled/swallowed/encrypted by the void. All the experiments are naturally locked in separate containers. 6. Klaatu barada nichto. We are indefinitely locked in solitary, incommunicado, for creating and using nuclear weapons. On ourselves. Immediately.
    • lainga 7y ago
      I find (6.) somewhat anthropocentric in that it assumes nuclear weapons are the nec plus ultra of destructive power. You might as well have said in 1917 that we were incommunicado for inventing chlorine gas, or shotguns (whose use the Germans did object to as a war crime!)
      • 7y ago
• roca 7y ago
  I find most Fermi-paradox arguments drift towards being too biology-centric even if they acknowledge the possibility or probability of a transition to machine-based life. For example this paper assumes that you need classic "habitable worlds" to colonize a solar system, but it's unclear why machines would need more than relatively small rocks or comets. The paper also assumes that each colony needs to operate as a continuous entity and can therefore collapse or experience massive cultural shift. But if it's all machines, then you can put some powered-off seed ships in long orbits for cheap self-recolonization (seems strictly easier than crossing interstellar space in the first place). I'd like to see more studies on the feasibility of those ultra-long-lifetime interstellar ships (assuming plausible tech like general AI). Maybe there are thermodynamic or other reasons why that can't be done. (Personally I'm in the camp of "abiogenesis is actually really hard so we're the first civilization in our light-cone; the doomsday argument holds, and will be a theistic eschaton".)
  • isoprophlex 7y ago
    Some fun ideas, because there's absolutely no reason why life should be so biological, as you say: - Some ancient civ managed to run computing hardware on the surface of cooler stars (there are stars that allow non trivial surface chemistry) - the same but with gas giant planets near their metallic or rocky cores - Gamma ray bursts are galactic compute nodes syncing data
  • ajnin 7y ago
    Machines need to be maintained. Machines of useful complexity include such parts as microprocessors. To create new or replacement parts, nothing less than the full Earth industrial complex is required. It's not clear how to package all that in a ship, including enough reserves to bootstrap an industry up to the point it is possible to build microprocessors. I doubt that "machine life" could subsist on a small barren rock with more success than biological life.
    • roca 7y ago
      It's very interesting to consider what would be required for a minimal industrial complex that supports microprocessors. My intuition is that it would be much smaller than "the full Earth industrial complex". Seems like a question that is actually answerable with research, and potentially important too as a hedge against our current industrial complex collapsing.
• radford-neal 7y ago
  The simulations in this article are compatible with the more abstract analysis in my paper at http://www.cs.utoronto.ca/~radford/anth.abstract.html http://www.cs.utoronto.ca/~radford/anth.abstract.html (see Section 7). The brief summary is that we observe two things: (1) we exist, with the full set of memories we have, (2) these memories don't include any evidence of other intelligences (I'll assume - readers who think they've ridden on UFOs can draw other conclusions). The existence of our particular civilization (in all its detail) is more probable if intelligent life is more probable in general (assuming one dismisses arguments about infinite universes containing all possibilities, so you can never conclude anything from anything). But if intelligent life is generally more probable, it's more probable that we have seen other intelligent life, contrary to observation. So the most likely situation given what we observe is a compromise - intelligent life is fairly likely (explaining our existence), but not really likely, or at least not really likely to explore other stars (explaining why we haven't seen any aliens). One unfortunate possibility is that intelligent life reaching our technological level is common, but getting to the level of colonizing the galaxy is uncommon. But that needn't be highly likely. It's also possible that there's other intelligent life out there not far away, in which case it may well be within our ability to detect it with a bit more effort. That's what one would conclude from this article as well.
  • deleted 7y ago
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• jnurmine 7y ago
  On Earth, there have been previous life-forms which have died out, there have been more or less intelligent life-forms which have died out (various dinosaurs and exhausted branches of hominids etc.), there have been previous civilizations with varying scientifical/technological achievements; but there has never been a species on Earth which has created a civilization as advanced as humans have. So, we are the first ones to reach this point on the Earth. Not the first ones ever, but first ones to get this far. If we assume the patterns of evolution observed on the Earth are nothing specific to Earth and they repeat throughout the Universe, there are/have most likely been life-forms (simple and complex) of varying degrees of intelligence, as well as civilizations of varying degrees of technological advancement. However, since we apparently see absolutely no trace of anyone else, either they failed to successfully bootstrap their colonies outside of their home planet/moon, or we got here first. It's unlikely, and absence of evidence is not evidence of absence, but someone has to be the first. Maybe it's us, from our little blue planet.
  • zizee 7y ago
    > but there has never been a species on Earth which has created a civilization as advanced as humans have. It's an interesting to think about what traces an industrial civilization like ours would leave behind if we were to be wiped out tomorrow. Most evidence would be gone in a few thousand years. Wait a million and it would be almost like we were never here. https://www.theatlantic.com/science/archive/2018/04/are-we-earths-only-civilization/557180/ https://www.theatlantic.com/science/archive/2018/04/are-we-e... https://news.ycombinator.com/item?id=19707426 https://news.ycombinator.com/item?id=19707426 Never say never :-)
• mnemonicsloth 7y ago
  It bothers me that the authors' assumptions are so controversial and that they hide them in the middle of the article. In the simulations the authors are using, civilizations have lifetimes, meaning that all of them end after a while. And that simply isn't supported by events. Technological civilization has never vanished even from our little one-planet civilization. Polities do decline, but there is usually someone there to pick up the pieces. In an interstellar civilization there would be more recovery opportunities: interstellar visitors who arrive to see why a collapsed planet went offline. The authors of this piece are asking us not just to assume that simultaneous disaster is possible on ten, a hundred, or a thousand planets. They are asking us to assume that it happens to every single time a civilization has achieved interstellar travel, and that it has been happening for the last ten billion years. Simultaneous catastrophes on thousands of worlds affecting millions of species for billions of years? Life arising only once could easily be the more plausible option.
  • adabsurdo 7y ago
    > Life arising only once could very well be the more plausible option Indeed I feel like coming to this conclusion is something that the authors - and most of us rationalist types - do not _want_ to come to. Because if you accept that hypothesis, then it follows as a consequence that an alternative view of the world makes a lot more sense: what if, rather than living in an emergent, random universe where life sprouts up everywhere, hundreds of billions of times, but somehow _always_ disappears before we can ever observe it outside Earth, we are instead living at the center of a universe where we are the sole intelligent species that ever existed? In that system of the world, the universe is being directed by beings existing outside its bounds - gods. A simulation created and managed by uncaring observers - as hypothesized by the likes of Elon Musk? Or a benevolent God in the Judeo/Christiano/Islamic tradition? The truth is that this alternative is being rejected a priori, indeed not even acknowledged, by the authors of the article or most people in this thread, because it is an affront to their core beliefs, not through pure logical reasoning.
    • danans 7y ago
      > The truth is that this alternative is being rejected a priori, indeed not even acknowledged, by the authors of the article or most people in this thread, because it is an affront to their core beliefs, not through pure logical reasoning. I think it isn't acknowledged because it is inconsistent with literally everything we have learned about physics and the universe, and even if it were true, as you said, they are outside this reality and don't care. They set the simulation parameters, and then walked away, so they are irrelevant. If however, you point to something like miracles occuring in our reality to back up the "gods" view, then you aren't really having the same discussion as the authors.
• pjdorrell 7y ago
  The boring answer is that the initial origin of life depends on a sequence of extremely improbable chemical reactions (even given the prior existence of the most favourable possible “organic soup”), and there is no other life of any kind in the observable universe.
  • baja_blast 7y ago
    life arose on Earth immediately after it cooled down and Earth then was nothing like what it is today. The organic chemical reactions are extremely probable not improbable.
• cletus 7y ago
  So this article started as a good intro and overview of the Fermi Paradox (which is somewhat of a misnomer because as far as Fermi was concerned it wasn't a paradox at all) but it faltered at the end when it talked about habitable worlds. This is a topic Isaac Arthur [1] has gone into great depth about. If you haven't found his YouTube channel yet prepare to lose several days of your life. I find his arguments here compelling. Basically planets only matter as a source of raw materials. Planets are highly inefficient ways of creating living area. The most likely outcome for a spacefaring civilization is actually a Dyson Swsrm. 1% of Mercury's mass used this way could create orbiting habitats that support a quadrillion people and fully utilize the sun's power output (a so called Kardashev-2 or K2 [2] civilization). And these are simply O'Neil Cylinders [3], which don't require any materials that don't already exist. The beauty of this is it doesn't require much more technology than we already have. Better yet, it doesn't even require commercial nuclear fusion (personally I'm not yet convinced this is even viable). Take this further and a K2 civilization is not subtle and is highly detectable. For it not to be violates thermodynamics. We've seen no evidence of any K2 civilizations within millions of light years, which suggests their existence is highly unlikely (within the cone of spacetime we can observe). Given this seems to be such a natural evolution you can extrapolate and say that we are pretty much alone. Remember it's not about what most civilizations do because it only takes one to go this road. The argument that no civilizations become K2 civilizations use much harder to swallow than a few do. This notion gets more absurd the more civilizations there are. [1]: https://www.youtube.com/channel/UCZFipeZtQM5CKUjx6grh54g https://www.youtube.com/channel/UCZFipeZtQM5CKUjx6grh54g [2]: https://en.wikipedia.org/wiki/Kardashev_scale https://en.wikipedia.org/wiki/Kardashev_scale [3]: https://en.wikipedia.org/wiki/O%27Neill_cylinder https://en.wikipedia.org/wiki/O%27Neill_cylinder
  • BurningFrog 7y ago
    I've never heard of K2 before. Really interesting! I suppose one reason we can't see them is that there is an even better model so advanced civilizations end up using, but we haven't figured it out.
  • Balgair 7y ago
    These are all under our current understanding of physics, which does a good job, but we know it's not the full picture. Matter, the stuff you and I are made of, is ~5% of the universe's mass-energy. We understand the physics of this stuff fairly well. Dark Matter is, as far as we can tell, is entirely made of stuff that falls down and does nothing else. Dark Matter is ~25% of the universe. We have a fair few theories of what Dark Matter is, if/how we can use it, how to make it, move it, etc, but it's still very active research. We have a toehold on Dark Matter. Dark Energy, which makes things fall up, is ~70% of the universe. We are almost completely stumped as to what it is and how it works beyond making the universe roomier. We're just totally knackered on Dark Energy. Any civ that is thinking that seriously thinking about (let alone putting down-payments on) discombobulating planets in order to make more lawns to mow and gardens to weed is very likely to have more than a toehold on Dark Matter and is likely trying to make Dark Energy levitate tequila shots. And that's just the physics that we know we're missing. K2 civs are probably far more aware of yet more dragons in the mists. So, concluding (correctly) that since we don't see the IR heat of K2 planet demolitions, that we're alone, is not the best conclusion. We've not a clue as to what the rules of the universe are yet. We can talk about strategy once we learn how the knights and bishops move about the board.
• rosybox 7y ago
  This is article went off the rails when it talked about evidence for past civilizations on Earth being undetectable: > The only real evidence after a million or more years would boil down to isotopic or chemical stratigraphic anomalies—odd features such as synthetic molecules, plastics or radioactive fallout. Civilization on the scale such as ours creates huge waves of extinctions in the planet's species leaving lots of evidence easily available for us to see that it happened. In addition we've affected the Earth's atmosphere with our carbon emissions and that's going to leave evidence behind as well that will last a very long time. Also, all that easily accessible oil that we've been using to power our engines would not exist, because nobody is going to be leaving such an abundant and easy to use source of fuel around. The oil and gas we use took tens and hundreds of millions of years to form. Finally, and not least of all, the quoted paragraph mentions radioactive fall out, but any radioactivity would be blatantly obvious unless this civilization used none of it. There would be a very clear indicator in our dating methods of any radioactive activity in the past. I think it's safe to presume that instead of some past civilization that didn't use the most abundant natural source of energy around, didn't make use of nuclear energy and somehow managed to leave the species record clean it simply didn't exist. I don't feel like it takes more than a few moments to just realize how unlikely that take is and shouldn't have been included in the article.
  • s1artibartfast 7y ago
    You might find the the paper [1] and HN submission interesting. I believe it addresses every concern you raised, and comes to the opposite conclusion. [1] https://fermatslibrary.com/s/the-silurian-hypothesis-would-it-be-possible-to-detect-an-industrial-civilization-in-the-geological-record https://fermatslibrary.com/s/the-silurian-hypothesis-would-i... [2] https://news.ycombinator.com/item?id=21840320 https://news.ycombinator.com/item?id=21840320
• mirimir 7y ago
  There are arguably too many unknowns to do much more than speculate. But let's say there's some other planet with comparable technology. At what distance could we detect its routine radio emissions?
  • fernly 7y ago
    No more than 1000LY, per this article: http://www.setileague.org/askdr/howfar.htm http://www.setileague.org/askdr/howfar.htm i.e. 1% the diameter of the Milky Way: https://www.universetoday.com/21998/the-diameter-of-the-milky-way/ https://www.universetoday.com/21998/the-diameter-of-the-milk...
    • mirimir 7y ago
      Thanks. I wonder what percentage of the sky those larger SETI telescopes have looked at so far. I tried searching the SETI site, but had no luck. But anyway, that's a small enough volume that it could plausibly be temporarily dead or quiet, as TFA argues.
• rubyn00bie 7y ago
  I guess the primary argument to this is the number of stars, and the amount of time the universe has been around... but like the universe is _very young_. Our universe currently has an expected lifespan of like a trillion years. That is to say, if it's lifespan is 100 years, it's currently a ~13 month old infant. There is a supremely _good_ chance we, humans, are and will be the creepy ol' species we write movies about that has colonized stars and existed "since the beginning." Should we ever successfully make it off this rock that and to another star that is... It's fun to think about too, how will our species handle billions of years of separation at distant ends of the universe? Will we use gene therapy to ensure our "look" and aesthetic, or will culture and evolution be unpreventable yielding humanoids nearly unrecognizable to our current form?
• snake117 7y ago
  This brings to mind Dr. Greer and the Sirius Disclosure project [0]. The first documentary, Sirius, is available on YouTube [1] and the second documentary, Unacknowledged, can be viewed on Netflix. To be clear, I'm not sure if I entirely believe in all of this myself. However, I don't regret watching any of it. At the very least I got some inspiration for short stories/screenplays. [0] - https://siriusdisclosure.com/ https://siriusdisclosure.com/ and https://www.youtube.com/channel/UCC6B4Y0oFACv9QBlf0ebBcg https://www.youtube.com/channel/UCC6B4Y0oFACv9QBlf0ebBcg [1] - https://www.youtube.com/watch?v=5C_-HLD21hA https://www.youtube.com/watch?v=5C_-HLD21hA
• deleted 7y ago
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• m3kw9 7y ago
  I think big filter is plausible where as we advance in tech, the probability of us accident using to kill off everything increases. It starts with nuclear weapons and then maybe later mini black holes, etc.
• ncmncm 7y ago
  I see two alternatives, each sufficient: 1. Expansionist civilizations eventually encounter another one, and reliably obliterate one another. (Note, this is not "Dark Forest": it requires no long-lasting structure of any kind, just the occasional chance encounter that turns out badly.) 2. Expansionist civilizations find goldielocks planets both unnecessary and limiting, and just leave them the hell alone. They probably mostly use Neptune-like planets, when they have a use for a planet at all. Maybe they are at "our" Neptune right now, and have not contacted us, because why bother? We're "made out of meat". <https://www.mit.edu/people/dpolicar/writing/prose/text/thinkingMeat.html> https://www.mit.edu/people/dpolicar/writing/prose/text/think...
• nkrisc 7y ago
  From our perspective, even if another species had colonized millions of stars, it would still be like looking for dust on a mountain.
• lenkite 7y ago
  (First wears tin-foil hat). It may be more likely that we are under observation and a mature inter-stellar space faring alien civilisation has commandments not to interact or interfere with the primitive natives. They occasionally mess up and then the UFO's are seen. But their propaganda department clears the mess up.