The Aurora hypothesis

Matt Williams has an interesting article at Universe Today on the Aurora hypothesis, a part of a long running series on the Fermi Paradox: if alien civilizations are numerous, where are they? The Aurora hypothesis is that the reason we don’t see signs of alien colonization throughout the galaxy is that most biospheres are not compatible with each other. In other words, just because planets are habitable by some lifeforms, doesn’t mean they’re settleable by foreign lifeforms. The hypothesis is named after Kim Stanley Robinson’s novel about human settlers on an exoplanet discovering that their new home has serious problems.

It does seem like the possibility of biosphere incompatibility is pretty high. As living systems, we are an integrated part of our own biosphere. Our systems depend not only on environmental conditions, such as the atmosphere and Earth’s magnetic field, but also on an entire ecosystem of other life, including a food chain, as well as many symbiotic relationships. Even the oxygen in the atmosphere is a result of other life.

A lot of science fiction pictures colonization working similarly to how European colonization worked in the Age of Discovery. But this was Europeans exploring and colonizing (and conquering) new regions within the same biosphere. Colonists of an alien biosphere might find themselves always having to wear environmental suits.

Colonizing space may be more analogous to life moving from the oceans to land. It’s not something that’s likely to happen without a change in the systems doing the colonizing. We see this already in the fact that most space exploration is done with robots. When scaling to interstellar exploration, the difficulties increase exponentially, which seems to make it inevitable it will be primarily, if not exclusively, a machine endeavor.

An advanced civilization could probably have self replicating probes, seeking out construction materials in a destination solar system to make new copies. These probes, as intelligent energy seeking reproducing agents, could be viewed as a form of life. (Over long enough time fames, we might even expect they would undergo evolution.) And I see no reasons in principle that what they produce couldn’t include engineered life in a discovered biosphere, life built out of material from that biosphere and tailored to function within it.

If so, then the Aurora issue would have been bypassed. Of course, this does assume that self reproducing machines are possible, but we already have such machines. Indeed we are such machines, just evolved ones rather than engineered ones. And we’re already starting to play with our design via genetic engineering. It also assumes that interstellar travel, even by machines, is possible. But the Fermi Paradox seems moot if it isn’t.

It does raise the possibility that maybe we were colonized long ago, but the colonizers just added new lifeforms based on our existing biosphere. These engineered lifeforms could have devolved over time while blending into the fossil record. But I think we’d still see at least some remnants of their technology, and a much larger discontinuous jump in evolutionary history than currently shows up. Although we can’t completely rule out the possibility we were uplifted by a Monolith or similar alien probe.

Anyway, while Aurora definitely raises an important issue, I don’t see it as a definitive answer to Fermi. But maybe I’m missing something?

74 thoughts on “The Aurora hypothesis

  1. I wonder if the reason why we don’t encounter alien civilizations is similar to the reason why, say, dogs, don’t encounter human beings. And this is to say, our concept of life does not extend into the dogs concept of life, nor vice versa, even though we might be interacting with each other. It’s really just as human beings that see dogs in whatever way that we see them. Dogs do not have a “conscious perception“ from a human standpoint reflecting upon their dog Ness: they simply cannot comprehend what human beings are because the difference between a dog and a human being so far is intelligibility from the Dog standpoint, is irreconcilable.

    So my question just goes to, would we even be able to recognize whether or not we encountered an alien civilization?

    Add to extend this analogy along a slightly different vector:

    I was reading a piece by some scientists, I can’t really remember what they called their area of science though. Basically they talk about magnitudes of life. That human beings measure everything by the human standard, of course. But, it may be that life itself actually occurs in orders of magnitude, not merely different types of quality of life, but indeed quantity of life. Like energy stages in an atom perhaps. The example that they give is like a redwood that’s 2000 years old. The lifespan of that redwood is 2000 years. Could we even reckon what a consciousness of a life that is 2000 years would even look like. And I think their argument kind of goes to that no we would not recognize it as life similar to what we know as life, which is to say, as consciousness, civilized, maybe.

    And then they even I think extended it to talking about some types of life that live within glaciers or within permafrost. Some of those microbes have been living for thousands and thousands of years. And so as a human being we could not possibly even approach what it would be like for a lifetime that extends that long. And so consciousness itself may have something to do with These “quantities of life”. And that could be a reason why human beings are not in countering “civilized life” out in the universe. Because we are the only type of art form of living, we are the only type of our particular type of quantitative life.
    I think the point they were making was, yes, there is a certain overlap in these quantities, just like energy stages of an electron are not fully 12345, but there can be divisions of those kind of stages, just as an analogy.

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    1. Interesting points!

      I think we definitely have to be cognizant that how we see reality is related to our evolutionary affordances. We see the universe as a primate from the Africana savanna, who has to use metaphors to understand the very small and very large, because we can’t conceive of them directly the way we can our immediate environment.

      For example, if we encountered a life form, maybe one that evolved in a much colder climate, it might be that its consciousness is orders of magnitude slower than ours. We might have trouble recognizing such creatures as conscious, much less intelligent.

      On the other hand, I think there’s something to be said for the fact that we and the other creatures both live in the same objective reality, under the same laws of physics. It seems like that ensures we’d have at least some overlaps in the way we perceive the world, some basis for communication and interaction.

      Of course, there are no guarantees. Isaac Asimov, in his book on extraterrestrial intelligence, made a point about the idea of rocks somehow being intelligent and communicating with each other, but we’re simply too disconnected to realize it. Maybe the rocks have profound philosophies that we can scarcely imagine. But if we can never find some common basis for interaction, for us they’ll only ever be rocks. His point being that we have to work with reality as best we can.

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      1. Yes. And it could be a reason why we will never find another kind of life similar to ours. It could be that a forest is indeed a civilization of intelligence of a certain kind of consciousness. And, it could be that what we are coming upon as physical reality, according to the laws of physics, is really just the way that our particular consciousness, just the particular way that information arrives in our particular kind of consciousness. I mean, it seems like every day quantum mechanics is finding out some thing even more ridiculous than we could’ve ever thought before under the name of science. Personally, I’m not sure if they’re discovering really anything about the physical world that is any different then I might find out if I analyze how I am showing up in the world. I ponder whether or not that the differences that we are seeing, that we are conceptualizing, is fundamentally only a difference in the symbols that were using. That a certain set of symbols mean or signal us, signal consciousness to have A particular relationship, that particular groupings of Symbols signal consciousness to behave in a certain way. For example, if I use numbers and what we generalize as mathematical symbols, the signal to consciousness confers a relationship to what is not the individual, say, not us. In the same way that internal to language, certain groupings of symbols indicate and signal to consciousness a fundamental truth. Which is to say if I say “you” then a whole series of physiological emotions arise, both in the cognitive as well as physical sense, to connote something particular. And perhaps this happens at all levels.

        So it is conceivable likewise that not only symbols, but indeed the world itself signals consciousness, signals human consciousness in this case two groupings of sensory data, such as “perception”, “consciousness”, “ conception“, etc.
        So it is that perhaps we will never encounter someone “like us”. Because we have a risen particular to our own type of Universal being, just as rocks may have likewise arisen as their own universal type of being.

        Anyways, all the philosophy aside, it could just come down to the simple fact that we will never encounter any other people, any other creatures that are “intelligently civilized” in a way that we typically like to think, Ola Star Trek and Star Wars. We will only encounter life to the extent that we have to compensate what we consider all these various facets upon which we find ourselves unfortunately unique and hopefully not so unique.

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        1. I’m with you on it being unlikely we’ll find other “people”, intelligent creatures who build a civilization. Or at least it may be a very long time before we encounter any, possibly billions of years, if the expansion of the universe ever gives us a chance to encounter them.

          By that time, we might have splintered and evolved into so many disparate factions, that we may seem as alien to each other as anything else might encounter.

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  2. No Von Neumann probes, which would theoretically avoid the biosphere issue, says Fermi’s Paradox remains intact, at least as far as that avenue of thought is concerned.

    I actually read Robinson’s Aurora and found it implausible. Spoilers: prions, if I recall, were the culprit. Turning around and heading back to Earth? Uh… yeah.

    But I can see that differing biologies might interfere/confound galactic diaspora. I don’t believe prions would be the issue, but just like HGWells’ Martian’s susceptibility to earthly microbes, imagine Gaian life being exposed to alternate DNA’d fungi, bacteria or viruses. My favorite apocalyptic novel The Girl with all the Gifts, has a premise where fungus is among us. Fungi is a 2+(?) million species strong kingdom. I would not want to have to live amongst an alien set of those sporific monsters.

    Then again, why send an entire Ark to a potentially hostile planet without some means of terraforming the place, Scorched Earth style? Creatures already there? Screw them! Manifest Destiny.

    My own research and presumptions on Fermi’s Paradox are documented elsewhere; bottom line? There is no paradox. Humans are 2^70th unique in the Universe. One of my favorite topics!

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    1. I haven’t read Robinson’s novel, but I did wonder about the prion thing. From what I understand, most proteins have a small functional area attached to an overall nonfunctional structure, which provides a frame of sorts. But you can have lots of differently sized and shaped structures with similar functional areas. So even if there’s evolutionary convergence on the functional part, I could see an alien protein just happening to have the right dynamics to influence the folding and misfolding of human proteins being unlikely.

      I agree on there not being any real paradox. Intelligent life seems likely to be profoundly rare. I like your 2^70 figure. That’s 10^21, which is only a few orders of magnitude smaller than the number of stars in the observable universe (10^24). But I’m curious how you calculated it.


      1. I love thinking about 2^?. It’s all about flipping a coin and the sequence of heads (or tails) in a row. Although the numbers aren’t exact they’re close enough. These are the approximate probabilities:
        2^10 is ten heads in a row, about 1/1000.
        2^20 is 20, about 1/1,000,000.
        2^30 is 30 heads about 1/1,000,000,000.
        And so on.

        I’ve been collecting probabilities regarding humanity’s technological existence and its current streak of luck. If instead of thinking only about the cosmic numbers of galaxies and planets and such, one includes all the improbable factors that, combined, allow us to have this digital conversation, I figure we’re around 2^70 lucky.

        Using that number, even if it’s off by magnitudes, any other intelligent race would have to have run the same improbable gauntlet as us humans.

        Isaac Arthur has a great set of videos on the Fermi Paradox, many of which I’ve used to fill in my numbers. Other factors like, humans wouldn’t have a civilization if it weren’t for trees, or grass, or live stock, and others. Count all the factors up and you get ~70 binary determinants.

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        1. Powers of 2 figure pretty prominently in information theory, with bits and all. When thinking about the parallel capacity of a quantum computer, each qubit is capable of being individually in a superposition of 0 or 1, but all of them entangled and collectively being in combined superposition of 2^numberOfQubits. So ten qubits allows 1024 concurrent states, 53 qubits being in 2^53 concurrent states. A 300 qubit computer can have 2^300 states, or 10^90, more than the 10^80 elementary particles in the observable universe.

          Sounds like we have a lot of similar interests. I’ve looked at the likely rarity of intelligence many times (such as: ). Although I’ve never taken a shot at explicitly quantizing it before.

          Sounds like I need to look up those Isaac Arthur videos!

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  3. I’m kinda done with speculation, but I’ll offer this hard fact:

    If one posits there are least six events in our history required for us to be here, and if we posit a very reasonable minimum of one-in-ten-thousand odds for each:

    (10^4)^6 = 10^24

    There are only 10^11 stars in the Milky Way galaxy. We’re a long-shot. The odds are overwhelming that we’re alone, not just in the galaxy, but in the local group.

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    1. I think you need to account for time in your calculations. If there is a one in 10,000 chance of some event happening in a given year, chances start to look good in a million years or so. I’m guessing that you get something like half-lives, as in, you need to find where there is a 50% chance of event x happening in, say, 100 million years.


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      1. Not just time, although I agree with that.

        Let’s say one of those events is development of life itself, which would likely be one of them. Not only do you have time but you also have millions of places on earth the event could have occurred and possibly multiple ways it could have occurred.

        The calculations would come out quite different, I think, if we do not assume that the six events must be unique. There could be six unique events in our history but a different set of six events elsewhere in the galaxy,. We shouldn’t assume life and intelligent life must come about everywhere through the same identical set of events.


          1. Indeed. In this case the large numbers involved are 10^11 and 10^24.

            The posit is that, in any given system, there is some sequence of events necessary for the outcome of intelligent life. As Seattle James says, time is a factor, and it’s one source of ‘large numbers of chances’ for those events which definitely affects the odds (and are harder to calculate).

            That said, there are windows of time and required sequencing. First a reasonable star. Then a right-sized planet forms at the right distance. Also large outer planets for shielding. Then it gets a large moon (and more iron for its core). Then single cell. Then multi-cell, and the sequence continues.

            The proposition involves this chain of events and just says that the odds of it ending in some kind of intelligent life, as a massive arm-wave, seems somewhere on the order of 10^24 given some very reasonable odds on a handful of events.

            But we only get 10^11 chances to play that game, so we’re many many orders of magnitude below good odds on an outcome.


    2. I tend to agree. I’m not sure we could even say our nearest neighboring civilization are in the Lanikea supercluster.

      10^24 just happens to match the number of stars estimated in the observable universe (at least per Google). I know it’s a quick and dirty just to make a point, but it’s interesting that it landed on one civilization in that scope.

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  4. I think you and Anonymole are mostly correct in that the first things to explore the galaxy will be self-replicating robots. But it doesn’t end there. The second wave will be projects. This will include terraforming planets, although contra Anonymole, I don’t think we’ll touch planets that already have life, for the same reason we try not to destroy habitats for spotted owls, etc. There will be plenty of resources without needing those rare ones.

    But I think there will also be *big* projects. The one that comes to mind regards our own sun. People say in some billions of years our sun will expand and consume the earth. Why would we let that happen? If it’s a question of running out of hydrogen as fuel, why wouldn’t we go collect some, from other stars, mebbe, and figure out some way to get rid of any problematic waste stuff if that would make a difference?

    The Ringworld series had a number of examples of such projects, the ringworld being the most obvious, but I also recall that the “puppet” race had a similar problem (aging star?), and so they moved their whole planet.

    The point is that such big projects will be obvious, and not naturally explicable.


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    1. I wonder if, having made the transition to forms that no longer require biospheres, if the energy would be expended to create them. The real projects might be more about infrastructures to capture and use energy. In that sense, we might expect to see Dyson swarms and the like. If so, the fact that we haven’t detected any seems notable.

      It’s been a while since I read Ringworld, but didn’t the puppeteers sling their entire solar system or something on a path out of the galaxy (because it was slowly exploding over a 50,000 year period)? Being cowards, they were too afraid to evacuate via FTL, and were terrified by the awe of the characters seeing their set up, because the characters might see it as a threat. They were cowards, but acting on their cowardice had made them immensely powerful.

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  5. Sure, send out self-replicating probes that can evolve in their new environment, and hope that they terraform the new solar system to support your kind of life. Better yet, have them send out successive waves of probes. What could possibly go wrong?

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      1. The trick is preventing it. Even if copying errors (induced from radiation or low probability quantum events) only happened once every several thousand years, they would amount to mutations, and over time they would add up. And if they made a particular variant more or less likely to replicate itself, you have natural selection.


        1. Not really. Natural selection “intentionally” has a mutation rate. It would not be hard to make the mutation rate of code essentially zero, just by having redundancy. Say you keep three copies of the code, and periodically check for mutation. Anytime you find one copy doesn’t agree with the other two, you just change it back. If you find that all three disagree, then something bad happened and you’re just borked (so just shut down).



          1. From what I understand, DNA does have redundancy and transcription checks. It keeps the copy errors down (otherwise we’d all quickly die from cancer), but can’t eliminate them.

            Along the same lines, the steps you describe would reduce the probability of copying errors, to something far lower than what happens in biology, but can’t eliminate them. The “master” version any checks could use can itself become corrupted. And if you have multiple copies, and they’re all corrupted in different ways, which one to trust? And what happens when the checker itself is corrupted?

            Ultimately, any system is going to be composed of molecules and atoms and be subject to corruption from all the sources of radiation in the universe and the inherent chaos of physical processes. We might be talking about billions of years here, but on such time scales, it becomes very hard to ensure fidelity.


        2. Yes there is some redundancy and error checking in DNA, but again, it is not perfect by “design”. There are two copies, but they are physically attached, and a mutating event happens in such a way that you can’t tell which half is the mutation. But if you had a third copy, you could.

          Note that there is no master copy. There are three equal copies, and wherever you find a place where one does not agree with the other two, you change it to match the other two.

          I can’t do the math, but I have a strong feeling that robots can be designed such that “unplanned evolution” is not a significant thing.


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        1. It wouldn’t make much military sense to program in evolution, but on further consideration I think what you are (or should be) concerned about is robots that learn. I haven’t thought much yet about learning robots, so maybe there’s some danger there.


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          1. If technology is rapidly evolving, and your devices might have to confront enemy devices, there is a huge incentive to attempt self-improving devices. Especially when the confrontations are expected to happen long after the launch of the initial fleet of devices.


    1. Yeah, science fiction has been there. I think both Iain Banks and Alastair Reynolds had technologies that got out of control in their replication. In Reynolds’ case, they set up a green habitat in every solar system they assimilated, turning the entire galaxy green, as some of the characters could see after they evacuated it.

      But realistically, I think the self replicating probes would more likely evolve over millions or billions of years.


  6. I wonder if anybody tried to use different approaches and calculations of a probability of intelligent life spread inside some galaxy and outside the galaxies. If, for any reason, a civilization expansion outside galaxies is prohibited or unwanted, then we will have to explain the Fermi paradox only within galaxies. That, for us, would mean within Milky Way.

    In this December paper “A Statistical Estimation of the Occurrence of Extraterrestrial Intelligence in the Milky Way Galaxy” ( an important data were presented. Per their modeling “a peak location for ETI at an annular region approximately 4 kpc from the Galactic center around 8 billion years (Gyrs)”. Our (Earth) case is an outliner – we are in suburbans but very young. The authors of the study did not discuss the thought that could also mean that a possibility is high for the Earth civilization to be ahead of other ETIs in our Galaxy.

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    1. I don’t know if anyone’s taken a shot at intergalactic spread. The biggest factor in spread outside of galaxies are the distances. The average star within our galaxy is something like 4-5 light years from its neighbors. But outside of a galaxy, that jumps to something like 500 light years, and I’m not sure if anyone knows the dispersion as we move further into the intergalactic void. And galaxies in general are hundreds of thousands to millions of light years apart. All of which scale obstacles to expansion dramatically.

      I heard about that paper, but haven’t read it. But I think saying we’re in a backwater really doesn’t do enough to explain the complete absence of any extraterrestrial activity. Even in a backwater, we should expect to see something. It’d be different if our star were in intergalactic space, or even in a cosmic void. In the galaxy, there just aren’t that many stars to reach given the time frames involved.

      We might well be the first. If that’s the case, an interesting question is whether we’ll allow (intentionally or otherwise) others to arise. Even just interacting with a biosphere where intelligence might develop could inadvertently remove necessary evolutionary pressures. Once the intelligence niche is filled, there may not be room for others.

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  7. We are often accused of being myopic in thinking alien life needs to be similar to our own. But if you look at any number of cycles in our “nature,” the water cycle, the carbon cycle, the nitrogen cycle and the oxygen cycle, there are very few substitutes anywhere on the periodic table to make the energy and provide the biochemistry that is a living organism.

    There are organisms that live without light. There are organisms that get their energy from the stew of chemicals emitted around volcanic vents. We see many variations, but there are basics in laws of physics and chemistry that don’t seem to be avoidable.

    I suspect that evolution will adapt any living organisms to their environment and since the entire universe shares the same 100 or so elements that I expect all life to differ planet to planet … but also that the mechanisms by which those organism live will be quite recognizable.

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    1. There is a view that the laws of physics constrain life to be a lot like Earth life. For example, while DNA doesn’t have to be formed the way ours is, there are innumerable energy advantages to its current structure. We might imagine an alien biosphere would have similar pressures, and therefore, similar structures.

      I definitely think there’s something to that view. We see plenty of convergent evolution in our own environment. For example, eyes appear to have independently evolved dozens of times.

      But it also makes me nervous. So far we only have our one example, but even within that one example, we see a vast range of strangeness. It’s possible we’re having failures of imagination, and extraterrestrial life will be strange in ways we haven’t yet conceived. I think of all the hot Jupiters we found out there, which no one had imagined ahead of time.


  8. I notice I approach this much differently. I just think what drives our behaviour really? In a way it are obstacles. Most of it is the obstacle to impress the other gender to reproduce and find food. But what if thechnology advances. We can clone or build ourselves. A lot of behaviour will be unnecessary. Come to think of it. What emotion will you build in yourself. What I mean is when you really understand living what is the point of it. You can decide to build a brain structure that sees a point in it or maybe you think what is the point of that. What is the point of exploring the universe. It just a specific desire of a specific brainstate. I think every very advanced creature will go full Buddha. It will choose not to exist. End the cycle. Maybe convert itself to a material structure of everlasting happiness. But who knows maybe one day they will show up. Wanting things they easily could not have wanted being so advanced.

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    1. Could be. It might be that most civilizations develop virtual realities and just lose themselves in them forever, or engineer themselves to be happy living very basic lives. But it seems implausible to me that every last one would. And if civs are pervasive, it would only take a few to spread throughout the galaxy. Although if all they find are giant computational substrates with “Do not disturb” signs, it might be a serious downer.

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  9. I think a hugely forgotten element is lifespan.

    In human populations we notice a decrease in population growth with increases in longevity, especially decreases in infant mortality.

    Organisms with increased lifespan may naturally have relatively smaller populations. And certainly any organism that could engineer near immortality would also likely choose to shrink their population size. If it didn’t the organism would quickly over consume its resources on its home planet or on any other planet it choose to settle. We often picture extraterrestrials as expansive and constantly in search of resources (which is why they attack Earth in the movies), but a successful extraterrestrial civilization would more likely be the opposite: small in demand on resources, small in population size, and probably very unobtrusive.

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    1. I can definitely see a species that has achieved immortality (or near immortality) arresting its population growth, but shrinking it in such a population seems problematic. If people aren’t dying off naturally, then who is removed to implement the shrinkage?

      I can also see some civilizations going down the path you describe. But given the proclivities we see everywhere else in biology, it seems unlikely to me that all of them would. And it only takes a small minority (assuming a significant number of civilizations) to be expansionist in a manner that we should see some evidence of.

      I do agree the idea that they’d attack Earth, at least for any of the reasons Hollywood comes up with, is pretty infeasible.

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      1. They would naturally thin out as they spread and no matter how long the life extension was there would still be some death either naturally or through accident. Given enough time, there might only be dozens of them in any particular region of the galaxy. The immortality fix might also be something of a blind alley in itself. Oddly many ET contact accounts tell of species seeking to breed with humans in a effort to revitalize their species.


          1. The book came in one day (thanks Amazon) and looks pretty interesting. It does strike me that humans seem to have some degree of embedded patterns in their neurological makeup. Buzsaki talks about this in The Brain from Inside Out but his patterns, I think, are perhaps more low-level and primitive. For example, they may be like Chomsky’s Universal Grammar that then gets modulated by social and cultural experience to a capacity to speak a native language. However, there might also be high-level patterns expressed as myth which even carry on to a degree in science. Have you noticed how the Big Bang theory in some ways has elements of myth? Both Freud and Jung frequently used myths in modeling human psychology and the book, of course, has discussion of Jung’s interpretation of UFOs as psychological archetypes. There might be fuzzy ground at the edges of human cognition that can only be understood as myth. There may be actual stimuli that are triggering it but the stimuli is so far beyond our capacity to understand it that the brain falls back to myth.

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          2. A few years ago, I read a book on religion by the late Robert Bellah. (There’s a post lying around somewhere on it.) Bellah makes a similar connection to myth, although noting that the word “myth” has developed negative connotations, he used “narrative”. We are creatures of narrative. Most scientific papers discuss a set of ideas along with mathematics or other precise notation. But popular science accounts always focus on a narrative. If you want to convince people of something, tell a story.

            But that’s always a shaky fit with a scientific theory. Back when I used to debate creationists, they always treated the big bang like an alternate creation myth. But for them, it was one missing all kinds of things. What caused the bang? Why were there all these unanswered questions? To them, it seemed a poorly thought out origin story for all kinds of missing details. Of course, it’s because some things are clear from the evidence and other things not, but that’s a non-narrative way of looking at.

            It’s also interesting to remember that the name “Big Bang” was coined by Fred Hoyle, a skeptic of the theory.

            But we are definitely creatures of narrative, and it’s probably very easy to see certain patterns, even when they’re not there, or necessarily the best pattern to use in understanding the phenomenon. An alien intelligence may see very different patterns in the same phenomena, although hopefully their scientists would drill down to similar structural conclusions.

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  10. The “Aurora Hypothesis” always felt like a reach to me. KSR had to hand-wave a lot to make it work (although the novel is still very interesting and good), and that’s not just hand-waving away stuff like “send robotic precursors ahead to prepare the planet in advance”. He had to posit that people living away from Earth would literally get sick and die earlier because they don’t have exposure to Earth’s biosphere, which apparently can’t be mitigated with biological and medical modifications or really duplicated elsewhere except through painstakingly slow terraforming.

    None of those seem likely to me, although in fairness generation ships seem unlikely as well. If future space-dwelling humans have to modify themselves to live better off Earth, they’ll do it.

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    1. I haven’t read the book. From all reports KSR is an excellent storyteller, so I imagine it makes for an entertaining read. But I’ve heard it’s largely designed to highlight the problems with the traditional idea of colonization via generation ships. Since the earliest science fiction stories that feature generation ships almost invariably show them in a way where things have gone very wrong, I don’t know that it was a message a lot of people needed to hear. (Who would want to be the first generation on such a journey anyway?)

      But the issues of colonization by natural biological humans may be one more people needed to have highlighted for them.

      I do agree that any such colonization will involved modified humans, at best. More likely is the machines will do the colonizing.


    1. From BA’s post:

      one of the more famous stories was from a signal detected by the very same Parkes dish, which turned out to be people opening the door to the microwave in the observatory kitchen before the oven had stopped, flooding the dish with microwave signals

      I find this funny beyond all rationality!

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      1. Who knows! What helps a bit is that the search is for civilizations deliberately trying to make contact, deliberately sending a signal they have reason to expect putative others might receive. There’s very little hope of picking up normal species communications. That signal is indistinguishable from noise in very few light years.

        (And, as you suggest, technology changes. Even our own planet no longer radiates EMF to the degree it once did.)


  11. Biosphere incompatibility would be an issue, for sure, but I don’t think that alone would stop an alien civilization from expanding beyond its home solar system. If you have the technology for interstellar travel, you surely have the technology for terraforming and/or somaforming as well.

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  12. Our assumptions (on what intelligent life forms do) are based on our “wisdom”, which, in turn, is specific for biological, organic life. However, that wisdom may not work.

    What if all advanced intelligent life forms at some stage are transformed into non-organic life forms (what we call an Artificial General Intelligence – AGI)? The common assumption is that we, humans – emotional consciousness beings) could not understand and envision possible goals of AGI, which is a set of non-emotional non-consciousness beings.

    Then an attempts to “resolve” the Fermi paradox (from our perspective) could be futile.

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    1. We are definitely constrained by our evolutionary affordances. Our perceptions of the world are predictive models which operate in terms of those affordances. In that sense, we’re evolved intelligences tuned to survive at certain scales and in certain environments. It pays to remember that when considering other systems.

      That said, it also pays to remember that goals are not something that exist in the laws of physics. They emerge in evolved systems, and any goals in an engineered system will be descendants of those evolved goals. In other words, I’m not sure the goals of AGIs will be that inscrutable. Their method of reasoning about those goals might be, but maybe not the goals themselves.

      But it’s definitely true we don’t know what we don’t know. Unless we’re prepared to forego all logical speculation (which doesn’t seem fun), I think all we can do is reason as best we can, but stay prepared to change our minds on new information.

      Liked by 1 person

  13. > Their method of reasoning about those goals might be, but maybe not the goals themselves. – The set of possible AGI goals may not include some of our possible goals and include some goals, which are not foreseen by us. Secondly, their system of prioritization and exclusion of goals could be different from ours. Put that together – and even our most general goals (like survival, or minimalization of energy used, etc.) could of not much use.

    Also, AGI civilization could be very different from biological civilization evolved through competition in evolution. AGI civilization may have only one being, or very few entities altogether compare to millions – billions of biological beings. The reasonings for civilization with only a few beings would be hard to compare with reasoning for civilization with billions of beings. The list goes on and on.

    Liked by 1 person

  14. This aurora hypothesis seems pretty sound to me. I consider space exploration to demand far too many resources for it to work out much beyond a given home planet, and even given future advances in robot technology. Our planet should essentially be our spaceship, and I’d think the same for any other intelligent life out there.

    Liked by 1 person

      1. Right Mike, except when you consider that parts for robots and other equiptment will be expected to get damaged from time to time given the rigors of space, and should be difficult to replace by means of materials from other planets (that is when these robots are even able to make it to neighboring solar systems). They’d have to build up quite a servicing network, and that network itself should also need its own otherwise home planet resources in order to be effective. It seems to me that the whole thing could get quite ridiculous regarding material and labor requirements. So I’m saying that one reason we see no sign of robots from other worlds, could be that they aren’t able to generate good enough supply networks to sustainably get very far from a given home world.

        Liked by 1 person

        1. Eric,
          The general proposition is that these probes would be like seeds, or spores, or zygotes, able to bootstrap an infrastructure in a new environment. Of course, a counter is that a seed only grows if it happens to land in a fertile piece of soil, a substrate rich in resources. It benefits from a rich biosphere all around it with lots of preprocessed resources. That’s even more true for a zygote, where the environment specifically evolved for its growth.

          In the case of the probes, it might be that a single probe finding sufficient natural resources in a location close enough to the star or other source of energy, is a gigantic hand wave, applying the seed metaphor in a context where it won’t work. The minimum for such a bootstrap might actually require a small (or maybe not so small) army of probes, which raises the difficulty of what needs to happen.

          Still, these are all engineering difficulties rather than anything the laws of physics are preventing. History hasn’t been kind to people who declare such challenges forever unsolvable.

          Liked by 1 person

          1. Okay Mike, as long as people are thinking about this in terms like that. I’m more of a pessimist regarding space exploration, seeing amazing technical challenges and little in terms of rewards. But I also don’t want to wreck other peoples’ fun thinking about this sort of thing.

            Liked by 1 person

          2. You might be right Eric. I actually share your pessimism for (biological) human space exploration. But we’ve sent robots all over the solar system, which seems like a promising start for robotic exploration. Only time will tell.

            Liked by 1 person

  15. I wonder how much of our desire to know about other intelligent life forms is motivated by a desire to know ourselves better. I think much of it is. I love good science fiction. But good science fiction is good because it give us new perspectives into the human condition. I think the same of our desire to explore other realms in science, in particular the possible discovery of new perspectives from which to understand ourselves.

    Personally, I think the prospect for extra-terrestrial life is huge based on the known science. However, the prospect for extra-terrestrial intelligent life is probably rare as it is here on Earth. Unlike humans, many species on Earth have lived for millions of years with no movement toward intelligence. It may be the same elsewhere.

    Liked by 1 person

    1. Well said Matti. I agree with all your points.

      Science fiction is definitely more often a mirror than a looking glass. I think that’s particularly true for media sci-fi like Star Trek. The ST universe isn’t really coherent. It’s more a distorted mirror to examine our own world and cultural issues. Rather than any kind of serious examination of extraterrestrial possibilities, Klingons, Vulcans, Romulans, Ferengi, and others really represent aspects of humanity, but disconnected in a way that makes the examination seem less political (usually).

      I think most extraterrestrial life will be unicellular. Complex life will be rare, but findable. I agree that intelligent life is likely profoundly rare, so rare that we may never encounter another intelligent species. If we do, it might be billions of years from now, and who knows what we might be by then. (Assuming there’s anything left of us.)


      1. It is the same I realize now. I was confused because there have been two separate signals from Proxima Centauri detected by the same observatory. One was five years ago and could be attributed to the microwave oven. This one is more recent and was monitored for 30 hours. Its modulations match Doppler effects that would be caused by movement of Proxima B.

        The article from SETI is recent and uses the microwave oven incident as a warning not to get too enthusiastic.


      2. The linked article concludes:

        “Yes, as long as we still don’t know, we should continue to consider the alien hypothesis viable. After all, any SETI detection is going to be dicey when we first make it … there will be plenty of calls for restraint intended to pacify the all-too-eager. But it’s reasonable to expect that someday one of these suspicious signals will, indeed, be the sought-after proof of intelligence on another world”.

        Liked by 2 people

        1. I remain skeptical, but I’m definitely on board with SETI making sure. If it does turn out to be aliens, on our nearest neighboring star, well, that would likely mean our fundamental understanding of the history of our planet and how we evolved needs serious adjusting.

          Liked by 1 person

          1. That it is so close would be a strong argument against it. However, the article points out it might be coming from some object behind it that could be millions of light years away. Even then it wouldn’t have an obvious natural explanation.

            Liked by 2 people

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