If we were to find life other than Earth’s somewhere else in the Solar System, the aftershock would be substantial. After all, a so-called ‘second genesis’ would confirm the common assumption that life forms often, and in environments that range widely. The implications for exoplanets are obvious, as would be the conclusion that the Milky Way contains billions of living worlds. The caveat, of course, is that we would have to be able to rule out the transfer of life between planets, which could make Mars, say, controversial. But find living organisms on Titan and the case is definitively made.
Ian Crawford and Dirk Schulze-Makuch point out in their new paper on the Fermi question and the ‘zoo hypothesis’ that this issue of abiogenesis could be settled relatively soon as our planetary probes gain in sophistication. We could settle it within decades if we found definitive biosignatures in an exoplanet atmosphere, but here my skepticism kicks in. My guess is that once we have something like the Habitable Worlds Observatory in place (and a note from Dominic Benford informs me that NASA has just put together teams to guide the development of HWO, the flagship mission after the Nancy Grace Roman Space Telescope), the results will be immediately controversial.
In fact, I can see a veritable firestorm of debate on the question of whether a given biosignature can be considered definitive. Whole journals a few decades from now will be filled with essays pushing abiotic ways to produce any signature we can think of, and early reports that support abiogenesis around other stars will be countered with long and not always collegial analysis. This is just science at work (and human nature), and we can recall how quickly Viking results on Mars became questioned.
So I think in the near term we’re more likely to gain insights on abiogenesis through probing our own planetary system. Life on an ice giant moon may turn up, or around a gas giant like Saturn in an obviously interesting moon like Enceladus, and we can strengthen our hunch that abiogenesis is common. In which case, where do we stand on the development of intelligence or, indeed, consciousness? What kind of constraints can we put on how often technology is likely to be the result of highly evolved life? Absent a game-changing SETI detection, we’re still left with the Fermi question. We have billions of years of cosmic history to play with and a galaxy that over time could be colonized.
Image: JWST’s spectacular image of M51 (NGC 5194), some 27 million light-years away in the constellation Canes Venatici. Taken with the telescope’s Near-InfraRed Camera (NIRCam), the image is so lovely that I’ve been looking for an excuse to run it. This seems a good place, for we’re asking whether a universe that can produce so many potential homes for life actually gives rise to intelligence and technologies on a galaxy-wide scale. Here the dark red features trace warm dust, while colors of red, orange, and yellow flag ionized gas. How long would it take for life to emerge in such an environment, and would it ever become space-faring? Credit: ESA/Webb, NASA & CSA, A. Adamo (Stockholm University) and the FEAST JWST team.
Crawford and Schulze-Makuch ask a blunt question in the title of their paper in Nature Astronomy: ”Is the apparent absence of extraterrestrial technological civilizations down to the zoo hypothesis or nothing?” The zoo hypothesis posits that we are being studied by beings that for reasons of their own avoid contact. David Brin referred in his classic 1983 paper “The Great Silence” (citation below) to this as one variation of a quarantine, with the Solar System something like a nature preserve whose inhabitants have no idea that they are under observation.
Quarantines can come in different flavors, of course. Brin notes the possibility that observers might wait for our species to reach a level of maturity sufficient to join what could be a galactic ‘club’ or network. Or perhaps the notion is simply to let planets early in their intellectual development lie fallow as their species mature. Wilder notions include the idea that we could be quarantined because we represent a danger to the existing order, though it’s hard to imagine a scenario in which this occurs.
But the Crawford / Schulze-Makuch paper is not exactly a defense of the zoo hypothesis. Rather, it asks whether it is the only remaining alternative to the idea that the galaxy is free of other civilizations. The paper quickly notes the glaring issue with the hypothesis, and it’s one anticipated by Olaf Stapledon in Star Maker. While any species with the ability to cross interstellar distances might remain temporarily hidden, wouldn’t there be larger trends that mitigate the effectiveness of their strategy? Can you hide one or more civilizations that have expanded over millions of years to essentially fill the galaxy? At issue is the so-called ‘monocultural fallacy’:
…to explain the Fermi paradox in a Galaxy where ETIs are common, all these different, independently evolved civilizations would need to agree on the same rules for the zoo. Moreover, to account for the apparent non-interference with Earth’s biosphere over its history, these rules may have had to remain in place, and to have been adhered to, ever since the first appearance of colonizing ETI in the Galaxy, which might be billions of years if ETIs are common. Indeed, Stapledon (ref. 29, p.168) anticipated this problem when he noted, from the point of view of a future fictional observer, that “different kinds of races were apt to have different policies for the galaxy”.
I always return to Stapledon with pleasure. I dug out my copy of Star Maker to cite more from the book. Here the narrator surveys the growth and philosophies of civilizations in their multitudes during his strange astral journey:
Though war was by now unthinkable, the sort of strife which we know between individuals or associations within the same state was common. There was, for instance, a constant struggle between the planetary systems that were chiefly interested in the building of Utopia, those that were most concerned to make contact with other galaxies, and those whose main preoccupation was spiritual. Besides these great parties, there were groups of planetary systems which were prone to put the well-being of individual world-systems above the advancement of galactic enterprise. They cared more for the drama of personal intercourse and the fulfillment of the personal capacity of worlds and systems than for organization or exploration of spiritual purification. Though their presence was often exasperating to the enthusiasts, it was salutary, for it was a guarantee against extravagance and against tyranny.
That’s a benign kind of strife, but it has an impact. The matter becomes acute when we consider interacting civilizations in light of the differential galactic rotation of stars, as Brin pointed out decades ago. The closest species to us at any given time would vary as different stars come into proximity. That seems to imply a level of cultural uniformity that is all but galaxy-wide if the zoo hypothesis is to work. But Crawford and Schulze-Makuch are on this particular case, noting that a single early civilization (in galactic history) might be considered a ‘pre-emptive civilization’ (this is Ronald Bracewell’s original idea), thus enforcing the rules of the road to subsequent ETIs. In such a way we might still have a galaxy filled with technological societies.
An interesting digression here involves the age of likely civilizations. We know that the galaxy dates back to the earliest era of the universe. European Southern Observatory work on the beryllium content of two stars in the globular cluster NGC 6397 pegs their age at 13,400 ± 800 million years. Extraterrestrial civilizations have had time to arise in their multitudes, exacerbating the ‘monocultural’ issue raised above. But the authors point out that despite its age, the galaxy’s habitability would have been influenced by such issues as “a possibly active galactic nucleus, supernovae and close stellar encounters.” Conceivably, the galaxy at large evolved in habitability so that it is only within the last few billion years that galaxy-spanning civilizations could become possible.
Does that help explain the Great Silence? Not really. Several billion years allows ample time for civilizations to develop and spread. As the paper notes, we have only the example of our Earth, in which it took something like two billion years to develop an atmosphere rich in the oxygen that allowed the development of complex creatures. You don’t have to juggle the numbers much to realize that different stellar systems and their exoplanets are going to evolve at their own pace, depending on the growth of their unique biology and physical factors like plate tectonics. There is plenty of room even in a galaxy where life only emerged within the last billion years for civilizations to appear that are millions of years ahead of us technologically.
Image: The globular cluster NGC 6397. A glorious sight that reminds us of the immensity in both space and time that our own galaxy comprehends. Credit: ESO.
Back to the zoo hypothesis. Here’s one gambit to save it that the paper considers. A policy of non-interference would only need to be enforced for a few thousand years – perhaps only a few hundreds – if extraterrestrials were interested primarily in technological societies. This is Amri Wandel’s notion in an interesting paper titled “The Fermi paradox revisited: technosignatures and the contact era” (citation below). Wandel (Hebrew University of Jerusalem) eases our concern over the monocultural issue by compressing the time needed for concealment. Crawford and Schulze-Makuch cite Wandel, but I don’t sense any great enthusiasm for pressing his solution as likely.
The reasons for doubt multiply:
Even if they can hide evidence of their technology (space probes, communications traffic and so forth), hiding the large number of inhabited planets in the background implied by such a scenario would probably prove challenging (unless they are able to bring an astonishingly high level of technical sophistication to the task). In any case, advanced technological civilizations may find it difficult to hide the thermodynamic consequences of waste heat production, which is indeed the basis of some current technosignature searches. Moreover, any spacefaring civilization is likely to generate a great deal of space debris, and the greater the number of ETIs that have existed in the history of the Galaxy the greater the quantity of debris that will drift into the Solar System, where a determined search may discover evidence for it.
Why then highlight the zoo hypothesis when it has all these factors working against it? Because in the view of the authors, other solutions to the Fermi question are even worse. I’m running out of time this morning, but in the next post I want to dig into some of these other answers to see whether any of them can still be salvaged. For the more dubious our solutions to the ‘where are they’ question, the more likely it seems that there are no civilizations nearby. We’ll continue to push against that likelihood with technosignature and biosignature searches that could change everything.
The paper is Crawford & Schulze-Makuch, “Is the apparent absence of extraterrestrial technological civilizations down to the zoo hypothesis or nothing?” Published online in Nature Astronomy 28 December 2023 (abstract). David Brin’s essential paper is “The Great Silence – the Controversy Concerning Extraterrestrial Intelligent Life,” Quarterly Journal of the Royal Astronomical Society Vol. 24, No.3 (1983), pp. 283-309 (abstract/full text). Amri Wandel’s paper is “The Fermi Paradox revisited: Technosignatures and the Contact Era,” Astrophysical Journal 941 (2022), 184 (preprint).
I don’t think the Zoo Hypothesis stands up. At least, not as an explanation for why we don’t detect any civilizations beyond Earth. I wrote about it on my own blog, referencing Mr. Gilster’s last piece. You can see it here: https://www.jamescambias.com/blog/2024/01/the-zoo-hypothesis-objections.html
Superb post! I’ll be referencing this with comments in the next Centauri Dreams article.
Wasn’t Fermi’s question a casual remark during a discussion about ETs? It seems to me that we have built almost a religious order around this question, not unlike the shopping list “memorabilia” in Miller’s A Canticle for Leibowitz. The many explanations for the lack of evidence of ETs or prior ET visits have become apologies for those committed to believing in a galaxy full of civilizations, and not unrelatedly for the initial, and perhaps continuing, justification for funding SETI. The initial meeting accepted a figure of perhaps 10,000 for the number of technologically capable civs in our galaxy that might be transmitting messages that we could listen out for. As no messages have since been received, the search widened – more radio frequencies, optical signals, transients rather than beacons, leakage, artifacts from space habitats, Dyson swarms, von Neuman probes, lurkers, etc. What about past visits in deep time? We have lots of explanations of why ET visits in the past, colonies, or established civilizations on Earth may leave behind no trace – a deep time component of Fermi’s question. Those who believe in “ancient aliens” or even UFOs say that the evidence is all around us if only we would look and accept their explanations of the “evidence”. This is not unlike the spirits craze in the late C19th and early C20th that was believed by many supposedly rational people including Sir Arthur Conan Doyle, the author of the hyper-rational, fictional, consulting detective Sherlock Holmes.
Religions, cults, and most beliefs can exist despite no supporting evidence for the basis of the belief, whether supernatural entities, models of nature, or human agency, although a single unambiguous example would settle the matter.
SETI has only to find a single unambiguous signal, artifact, technosignature, or other proof of intelligence to prove that at least one other technological civilization exists or has existed, and therefore more may well exist. This existence would also, by inference, demonstrate that abiogenesis or some form of panspermia has resulted in life being common wherever it could establish itself. We wouldn’t need a biosignature, although biosignatures would be a test of how common living worlds are. SETI has traditionally assumed civs were bound to their home system, only able to communicate by radio. The many speculations suggesting this narrative is wrong seem close to being disproved if our first tentative steps of interstellar travel by our probes are achieved. If Breakthrough Starshot achieves a flight within a century, any ET civilization observing its flyby would be having its own “‘Oumuamua is an alien sailship” moment that would be correct. If humanity advances technologically, a millennium from now might well see humanity colonizing other star systems in whatever form we take.
We should certainly do searches for SETI, but we should also set some conditions about when failure to find evidence would indicate that the hypothesis has a high probability of being wrong. As Richard Dawkins said about his lack of belief in G*d, he is an agnostic who is 99% atheist, but cannot rule out G*d exists as a negative cannot be proven. In statistical parlance, one’s Bayesian priors for G*d are extremely low.
In the absence of a message or technosignature, a search for life seems our most likely approach that will result in success. A sample of life in our system, especially one that was unambiguously from a separate abiogenesis would be the best result as the knowledge we gained would be so much richer. But if a biosignature was detected on a number of exoplanets that could not be explained by abiotic processes, that would be an important achievement and might stimulate the drive to build advanced telescopes (a technological and secular equivalent of cathedral construction) to make more detailed observations and to send probes to investigate more closely (the secular equivalent of missionaries?).
“We should certainly do searches for SETI, but we should also set some conditions about when failure to find evidence would indicate that the hypothesis has a high probability of being wrong.” Since my memory of college statistics is in the distant past, I asked ChatGPT “How many stars in the galaxy would we have to survey and find no evidence of intelligent life in order to be 95% certain that our sun is the only star with a planet harboring intelligent life.” For the sake of simplicity I assumed 100 billion stars in the galaxy. ChatGPT refreshed my memory regarding the formula, explained the formula, and then said it was only necessary to survey 22,000 stars to be 95% certain we are alone in the galaxy. Of course how you define “intelligent” makes this answer meaningless, but I think SETI has already surveyed a few thousand stars. So maybe 20,000 to go? We might have a disappointing answer within a decade or so.
That question seems well beyond ChatGPT’s ability to answer. It would have to be making broad assumptions about the life styles and distribution of space faring peoples Would you share the chat?
The only signals SETI can reliably detect are intentional transmissions directed to us. Unless you assume an even distribution of beacons throughout the galaxy, a random search pattern can’t build a statistically meaning prediction.
Most of the math shown in ChatGPT’s answer does not copy legibly into this comment box. However the last paragraph does copy. ChatGPT said:
“So, according to this simplified model and assuming a very low probability (p=0.001), you would need to survey at least 22,000 stars in the Milky Way to be 95% certain that no other star in the galaxy has a planet with life except for our Sun. Keep in mind that this is a rough estimate and the actual number could be different depending on the unknown probability of p.”
I had the same thought you did; that the range of SETI’s search ability is limited, and therefore not a true random search of the entire galaxy. For example I doubt SETI can search stars on the other side of the galaxy.
When asking a statistical question like this , as Carl Sagan, noted, long ago, an important characterization must be included. What are the error bars? What are the uncertainties in the factors that went to making the estimate? Maybe one can ask ChatGPT to do this? A 95 percent confidence interval is a good question but how did it get that?
It appears that ChatGPT spit up an answer using mundane frequency statistics. It’s applying the same method used for the well known “Birthday Problem”.
https://en.wikipedia.org/wiki/Birthday_problem
It is completely inappropriate for estimating the prevalence of life in the galaxy for reasons that I hope are obvious.
ChatGPT certainly has its limitations. But I think statistics will eventually provide a good answer. For example, if there are a million technological civilizations in the galaxy and half of them are sending out signals that we can detect, then you can crunch the numbers and determine how many stars you have to survey to have a 95% chance of finding one of these signals. The more stars we survey and don’t find a signal the more likely it is that nobody’s out there sending signals. Of course the key phrase here is “signals that we can detect.” If they’re sending signals we can’t detect then that’s a different problem. Or if they’re a civilization still using signal flags and couriers we won’t find them either.
You cannot perform statistics on assumptions. You cannot perform statistics on data that do not exist.
I disagree. Assume you think your backyard pool is polluted with microscopic plastic particles. You know the size of the pool. So you scoop up a gallon of water from the pool and test it. You find no particles. So you keep scooping up gallons from different places in the pool and testing them. You find no particles. At some point you can be 95% certain there are no plastic particles in your pool. Of course this means there’s a 5% chance there are particles and you just didn’t find them. But you can perform statistics on assumptions.
That water? You’re gathering data, not assumptions. You formed a hypothesis and tested it. That’s science.
Assumptions are put forward in lieu of data. You can use statistics on the latter but not the former.
Yes. I see your point. Microscopic plastic pollution is real. We have found evidence of it in many places. Extra-terrestrial civilizations is just an assumption.
Regarding aliens, we’ll never have a shortage of hypotheses. The concept of a “zoo” is diffuse and we see many variations played out on Earth. For a few decades it has been in vogue in academia to idealize the “noble savage”, and to discuss with all apparent seriousness the ethics of leaving “uncontacted tribes” in a utopia devoid of medical care or a role in local politics, with predictable results. ( https://www.nationalgeographic.com/science/article/140403-brazil-peru-amazon-rainforest-uncontacted-tribes-finai-illegal-logging-world ) Much weaker but conceptually related distancing has been tried in the political realm, with notable enclaves such as Fristaden Christiania in Copenhagen. The moment authorities pretend not to notice something for the sake of a more convenient relationship, they have taken the same path, potentially, as unobtrusive aliens.
A conclusion I’d draw from such cases is that a “zoo” doesn’t need to be hermetically sealed to have some relevance; nor are those operating it necessarily sincere in their intention or practice to keep it that way. It’s more a matter of managing public image and adjusting the degree of power projection as desired. In recent years there have been intensely appalling situations in locales like South Sudan, Tigray, Artsakh, Darfur… yet people have become accustomed to knowing very little about them. If so many innocent human beings can be cruelly hunted down or routed from their lands with so little comment, surely a handful of well-maintained flying saucers with carefully designed self-destruct mechanisms won’t have to leave much impact, especially if some misdirection is thrown in.
Alternatively, popular sci-fi series (“Men in Black”, “Torchwood”, “They Live”) favor the notion that the aliens (or their collaborators) are quite lax when avoiding detection, and instead build the bars of their zoo in the minds of Earthlings. Given the intense post-2001 research focus on all forms of surveillance technology, such as perfect lenses and multi-photon imaging technology, we have enough reason to worry even Earthlings could find a way to identify and destroy unwanted neurons or axon terminals in the brains of human subjects, and to do so from some moderate distance. Still, the same level of technology would allow true invisibility, so I’ll hold out hope for a more passive approach.
A cleaner explanation could be that the closest aliens may have evolved to become too different from humans to be recognized. If they can encode memory and logic elements into the fleeting noncovalent interactions of water molecules with one another, they might have a city of thinkers hidden inside the body of each human, tree, or ocean wave, feeling no need to disrupt the crude, approximate logic circuits that operate in our cells. Though they could choose to do so, there would be philosophical conundrums. If they decide to save one life, destroy one tumor, when do they stop? Would they go on to keep people alive indefinitely, want it or not, taking control of these crude organisms (even against their own self-destructive and homicidal desires) only because they happen to be part of the natural environment? One which now they’ve made unnatural? The presence of highly advanced life, able to do anything at all, leaves us with the question of what they want to do to us… and if that is nothing, then we may see nothing at all.
The most straightforward option to me is that the aliens are not concerned with whether they are contacted or not, but only with the method of contact. I suspect they think it is impolite to rattle all the pots and pans on a planet to deliver a voice message, or to lower a tin god in a machine to make announcements on the Capitol Mall. My guess is that the polite thing for them to do is to go about their daily business, whether that be a simple pastoral life or sucking plasma from the heart of their star, and wait for us to observe them. When we, of our own free will, can see them as they are — and notice that they are looking back at us — then we have made the first step of a gentle and nondisruptive first contact. By this standard all we need to do is continue our campaign of scientific exploration until we happen to find something.
Please forgive me for reproducing these comments here (they were a late response (just before the new thread appeared) to the previous thread; “Life Elsewhere? Relaxing the Copernican Principle”). But I feel they are particularly relevant to this discussion of the Zoo Hypothesis as well, so I have taken the liberty of reproducing them here in case you missed them earlier. I feel these are important but controversial topics, and I welcome a critical response. Again, please forgive my presumption in repeating previously submitted text verbatim, but I feel it is relevant to this discussion.
henry cordova on January 4, 2024 at 23:45
Fermi’s question has been answered. Other civilizations (if they do exist) are too few and too far apart, in both space AND time, enough for us to have had an encounter with them. Besides, WE haven’t been here long to provide any convincing records or history of such an encounter. I agree with Fermi, no one has come to visit, but it doesn’t follow from that that someone didn’t come in the distant past, or will come in the distant future.
I dislike the entire “Fermi Paradox” idea, it provides a real obstacle to science and conjecture in this area. We just haven’t been civilized long enough to even recognize a sign of alien visitation or communication, How long have we had radio, telescopes, astronomy, biology, space travel? A century? Two? That’s only a heartbeat of deep time. We just haven’t been around long enough, or been smart long enough to have recognized and properly interpreted an alien visitation even if it happened. The great civilizations of our past (Rome, Greece, China, Egypt) would probably have considered alien landings as religious events. Our ancestors were just as smart as we are, but someone would have had to explain to them just what was going on.
No. Lets get rid of the Fermi Paradox, once and for all. Even if Enrico was right, he was right for all the wrong reasons.
henry cordova on January 4, 2024 at 12:01
These sort of speculations may be useful, but they are still premature. We simply don’t have enough information upon which to base them. No, I’m not suggesting we should stop thinking about these things until we have enough knowledge to decide them once and for all. Even a totally cockeyed idea can get us to ask the right questions and to devise experimental tests. But we should still be careful that we label our conjectures carefully, and that we are aware they are just that, conjectures. Our experience so far has shown that when we finally do figure something out, it usually turns out to be much simpler, or much more subtle, than we had first imagined. Past experience is no guide to future revelation, but we should still pay attention to it.
One thing that has always bothered me is the “zoo hypothesis”. Approaching this conjecture with our usual lack of data, some logical objections to it should still arise. If we assume the universe is so crowded with civilizations that they have developed and administer a protocol to quarantine newcomers until they have matured sufficiently for membership, we must assume these civilizations have similar capabilities and goals. But the very suggestion of a plurality of interstellar communities suggests they are all vastly different from one another, that they have different ages, resources, cultures, biologies, evolutionary development, etc. They are all different! What are the chances they could agree on anything, much less cooperate effectively in carrying it out over cosmic time periods. No, although it might be possible to conceive of scenarios where something like a zoo hypothesis is possible, it is much easier to come up with reasons why it is extremely unlikely.
At this point, we know very little. But we do know enough to make some reasonable guesses. The circumstantial evidence suggests microbial life is probably common in the universe, multicellular life is rare, and intelligent life rarer still. Intelligences with the ability and desire (and resources, and long history, and stable environment) to develop technology capable of interstellar communication are probably the rarest of all. But these are all just qualitative speculations, We have next to no quantitative knowledge.
All we have to go by is our past experience, and we can’t even seem to agree what that is. My own approach as an amateur philosopher and metaphysicist is to rely on my intuition. And why not? I am knowledgeable on these matters, well acquainted with my contemporaries’ views, and I have spent a great deal of time thinking about it. From a Delphic point of view, I am just as qualified as anyone else to put forward a suggestion.
I suspect there are, at most, only a handful of intelligent civilizations in the galaxy right now; perhaps only just one, our own. There were probably others in the past, and others may arise in the future, but in either case, not many. I may very well be mistaken, but I am certain I have not deluded myself. If I were biased, I don’t think I would have arrived at that conclusion.
The “Rare Earth” theory estimates there are an average of .7 technological civilizations per galaxy in the universe.
Or interstellar colonization is much harder then we assume. Or everyone is communicating using solar gravitational lens stations. Or the total mass of one solar system provides everything a civilization needs for billions of years. Or the higher your tech level gets, the more efficient your power generation. Or conquering a primitive planet doesn’t give any benefit. Or the probes are there, we just haven’t spotted them. Or or or or or or….
Given how little of our own Solar System we’ve explored, the confident assertion that if they existed we’d know about them is staggering.
Just a quick sidebar on SETI, I think we’re orders of magnitude away from being able to declare it a failure. My biggest problem with looking for deliberate signals is the effect of time, just how long could we expect the trouble and expense of sending signals we could hope to find through the galaxy? Millions of years seems asking a lot.
I think life exists out there, and I also think technological civilizations are rare in both space and time. As for the article today and the one from yesterday…
Count me in as a person who dislikes both the Fermi Paradox (especially the “they should’ve colonized the galaxy by now” bit) AND the Drake Equation; too much worshipping now being done at the altar, when we should recognize that something from sixty odd years ago isn’t immutable. Also, while I am being a curmudgeon, I don’t like the Kardashev scale and the implication that an ETI will scale up to use all the power of a galaxy.
My idea for why we haven’t seen signs of interstellar transportation… they don’t WANT to. I use my kids and the staff that used to work for me when I was a lead as examples: they’re the normal ones, and we are the outliers. In other words, people who inhabit this board are a tiny, tiny, tiny, part of a society more glued to the Kardashians than Kardashev .
Simply put: there’s no interest in wider society for a lot of space science, and if we are playing the game of ETI “MUST” want to colonize space because we want to (but only the “we” on this board, not wider society), then we are being way too anthropocentric. Fine then, I say we use that same principle and say that every ETI society is like us in other aspects too and 99.9999% of them have their tentacles and eyestalks glued to their version of the iPad.
Space exploration is hard and expensive and also boring, and they care to waste time, money, and effort to ensure Jaybob Slugmeister III’s ancestors who were decanted on the worldship made it to some star they’ve never heard of after 1500 years.
The argument you cite for space colonization is not the one normally used. Sagan believed we were natural explorers. There was certainly the great age of exploration. Our ancestors certainly radiated out from Africa, colonizing almost every place that was suitable and could support humans. But generally, human migration was very slow and most migration was probably due to population pressures. People migrated to find new places to live that were not yet occupied. I think that is similar to the reasons every animal migrates as the competition for food becomes more intense. Even plant populations expand, simply by the spread of seeds by natural means, whether wind, water, or animals.
Migrating to other planets is not as simple as migrating on Earth, but given the technology to travel, there seems little reason to believe it will not happen, perhaps just by a few. Populations don’t tend to migrate en masse, but rather individuals do, for disparate reasons. The majority of the global population will not decamp and settle elsewhere, but some people will, just as groups and individuals traveled to the Americas once ocean sailing ship technology was developed.
Travel across the Atlantic by the Mayflower took 2 months, about the same as Heyerdahl took in his reed ship Ra experiment. If took 4 days for the Queen Mary steamship. Today an airliner makes the trip in about 8 hours, while the supersonic Concorde could cut that time in half – barely time to eat a meal and watch a movie. We don’t know what the potential for speed for interstellar travel will be, but even if restricted to c, the subjective time would be reduced towards zero by time dilation, so boredom would not be an issue. Travel at lightspeed would feel instantaneous, even if many years had actually passed. Slower travel while in an unconscious state, or switched off if a machine would also seem near instantaneous.
As for cost, that depends on the technology and how it is used. Aircraft would have been immensely expensive if thought about when the Mayflower took the Pilgrims to North America. Jet airliners are immensely expensive, but almost continuous operation carrying many paying passengers means that ticket prices are very inexpensive today for almost anyone living in rich countries. When Brits took up the offer of assisted passage to Australia after WWII, travel times were weeks but the cost of just 10 pounds was a 1/10th of the actual regular ticket price. The expense was borne by the government. Depending on the method of interstellar travel, the costs could be quite low. We just don’t know. The only thing we do know is that without some form of FTL, actual travel times of human mass meat bodies by physical starships will be very long and therefore the costs high. But we don’t know if that will be the solution that is used. It may look as quaint as biplanes or wooden sailing ships look today, compared to jet airliners or cruise ships.
Whether humans, post-humans, or our robot descendants are the ones that will explore the stars, is another issue. But if/when the technology to disperse becomes available, our human culture will expand in whatever form it takes.
Alas, here we are in the 21st century and aircraft are but glorified motorized kites. The Space Shuttle was a national embarrassment – a modified DC-3 with stuck-on bathroom tiles and strap-on oversize Chinese firecrackers.
What will happen when we become immortal, we are not that far from it and your lifetime net worth will become infinite. We are small minded in a huge universe but when you live forever are you going to go into the jungle and hunt tigers…
Myrmecologists may pursue their interests, but the lack of reciprocity from the objects of their studies may be more from a disparity of intelligence than a lack of technologic sophistication. On the other hand, we would be wont to investigae any inkling of alien manifestation in our neck of the woods.
With enough technologic sophistication aliens may be able to keep us penned up as in a zoo, as part of a study or to protect us from ourselves. But even if the plan were open-ended, our technologic progress (barring self-destruction) could bring it to an end.
Perhaps less like a zoo with supportive zookeepers and more like a nature preserve, but becoming more like “Lord of the Flies”.
Where is Klaatu when you need him to tell us we had better shape up or…. whatever passes for Gort these days will be unleashed?
If the universe is constructed more like 11-dimensional strings, then travel across space would presumably obviate the restriction of c. But that would apparently create time paradoxes…or would it? If the end product of the evolution of intelligence is the development of vast AIs, then perhaps they are already observing us even though we cannot see them. I think they would pay no more heed to, nor intercede in, our self-destructive behaviors than we do to ant vs termite “wars”. No friendly but firm Klaatu, nor dangerous but “controllable” Gort, just dispassionate observers with goals of their own. Deities in all but name.
The main problem I see with the Zoo Hypothesis is that if there are multiple ET civilizations then ALL of them have to agree to engage in zoo keeping.
But if we only have one zookeeper or perhaps just a few, would the hypothesis then be compatible with the situation? [I don’t believe so unless the zookeepers could exert total control over all entities in their civ, or the zookeeping civs were single entities, not populations.]
I think the greater problem is that they also have to hide their presence in some way, which rather restricts them. OTOH, if there are predators, the zookeepers are already hidden and perhaps are either altruistically trying to hide us too, or…frightful thought, using us as decoys.]
Prof./Dr. David Kipping’s latest musings might also be relevant:
Outlasting the Universe
I have to agree with other comments on this post. Too much speculation and academic papers on too little data.
In order to prove that conjecture, I hereby present my own speculations :-).
ET civilizations are effectively undetectable, at least with any technology we are likely to have in the foreseeable future.
The reasons for this in order of decreasing mundane-ness are:
1. Inverse square law – we don’t have any nearby technological neighbors.
2. Encoding & encryption – the more sophisticated & efficient a communication system is the more it looks like EM noise. Add encryption on top for extra difficulty.
3. ET civs use gravitational lenses for interstellar communications – There have been a number of good articles on this site on this topic. The side effect is that it makes interstellar comms invisible to a 3rd party observer.
4. ET civs use “phased neutrino” comms – or anything else that would be extremely difficult for us to detect.
5. ET civs have cheap FTL or NAFAL drives – its simply cheaper and/or faster for them to physically deliver messages :-).
PS the most annoying speculation on the “Great Silence” is some variation of insert current perceived (human) social and political problem, then speculate that, that is the reason for non-detection. David Brin has been a recent culprit of this one, recurrent feudalism in his case.
A thought in connection with “cosmic wilderness” hypothesis discussed earlier.
Maintaining a zoo in a galaxy teeming with technology is like maintaining a pristine forest inhabited by native tribes and surrounded by high-tech countries. In Amazonia, no need for special activities. In a suburban area – not so trivial. In the middle of megapolis – that would take an effort. But there’s major difference. As natives advance, both boundaries of the forest and it’s “naturalness” must be expanded and improved to maintain the “zoo state”. Add galactic differential rotation, and things become even more complicated.
Yes, an advanced interstellar society capable of spreading all over the galaxy is possibly capable of maintaining the zoo for us at our current stage. No junk in the forest and no city lights on the horizon, not really demanding. On the other hand, it’s still quite a job even at our likely end-XXI-century level, and much more difficult than it was century before. Every Kardashev-1-scale technosignature must be concealed or removed from vicinity of every stellar system within tens of parsecs (gravlens would get it) and every single piece of junk must be removed from Earth and from locations of interest on the Moon, Mars, etc, where we could stumble upon them. The traces of removal must be removed, too, on dead worlds they would stand out. The same for other emergent civilizations, if technogenesis which produced the first ones is not suppressed after they mature.
The latter is arguably much easier than zoo-keeping for all rates of technogenesis. More, the difficulty of zoo-keeping increases much faster than that of Inhibition when natives advance. Compare zoo-keeping needed for us with just flinging a 100 km-wide planetoid from Kuiper Belt at Earth. Or a swarm of 10000 km/s Daedalus-class thermonuclear-powered projectiles, with the same total kinetic energy but oomags shorter preparation and warning time. We could shoot martians with these in the next century, if really needed.
If a galactic society is capable of zoo-keeping up to Kardashev-I scale, it is highly unlikely that emergent civilizations would present significant and unforeseeable danger. The Dark Forest state exists between equals and in the dark, not between the Empire and native tribes. It’s much easier to do nothing and then to make contact and explain the rules when natives reach the level at which they likely will discover they’re not alone.
So, the question is – why zoo-keeping should be worth the effort, especially compared with Inhibition or “doing nothing”?
Imho, the effectiveness of the “exclusivity principle” is exaggerated. Imagine running a bingo session and at closing someone approaches claiming that because the ball tumbler conceptually contains the sequence they needed, they should have hit BINGO. You would tell them that the finite nature of a session renders an argument based on possibility moot. The volume of space implied by the Fermi question is finite. As well, we should consider deep time as an environment that will select for and against specific traits. The possibility of being in a jungle ecosystem where it may only take seconds to find signs of life does not rule out being in a desert ecosystem where it may take days.
Many of the arguments against the zoo hypothesis assume space faring peoples will most likely be loud and build lots of mega-structures. As has been discussed frequently here, economics will likely, not possibly, select for efficient and productive EM transmissions. Internal communication within the civilization will be as low powered as possible, divided among frequency bands and encrypted. They will be quiet. We should also expect economics to select for the most efficient use of power, waste heat will be minimized. They will be tepid.
For the sake of simplicity, consider all the infrastructure for a stellar civilization as one large machine. Assuming any non-zero percentage and rate for replacing components predicts that the size of the machine is inversely proportional to lifespan. This should hold true even if it is possible to transform simple elements, even subatomic particles, into complex elements. The machine can not achieve perpetual motion. I don’t see how deep time can select for mega-structures. They won’t be plus-sized.
We don’t know what most of reality is made of and our best theories are incomplete. At best, Dyson and Kardashev were equivalent to lung fish peeking their heads above water speculating on the nature of the T- rex and eagle. That isn’t meant to diminish their intelligence or creativity, even the smartest lungfish is ignorant of snow covered mountains. Maintaining our zoo, and every zoo will likely be bespoke, may only require not introducing themselves.
While reasonably true for our type of machines, it is not for self-repairing machines. The ultimate is machines based on life, which as we know on Earth, the biosphere machine has lasted for at least 3+ bn years and not only self-repairs but evolves too through Darwinian selection.
We can easily imagine a collection of non Neumann replicators forming a large, complex “machine”, where each replicator has a function in a hierarchy, starting with a “cell”. As long as the collection has access to feedstocks and energy, it can last a very long time, perhaps even evolving new forms over time.
I don’t rule out your basic idea that large space megastructures perhaps are non-sensical for the technologies ETI can deploy, or that a biosphere is their ultimate, living “machine” that we would think of as a natural system, rather than designed (at least initiated).
We tend to project ETI’s motives and technology based on our experience. We are especially vulnerable in terms of our extant and foreseeable technologies. Space stations become enlarged in size and number and become Dyson swarms. Cities become larger and taller, ending up with world cities like a Trantor or Coruscant.
As we see with our aging infrastructure, the more we build, the more we must maintain or replace. The US is particularly bad at maintenance, but it is a problem throughout the globe. Eventually, the decay becomes impossible to manage and a polity needs to start afresh. Venice is a crumbling city compared to its heyday. One day, Hong Kong will become like Venice. All that over-building in China is a massive, probably unfunded, future maintenance task.
Biospheres, however, are self-maintaining, even reasonably resilient to massive shocks given enough time. If I was to design such a system like a Dyson swarm, I would look to technologies that make each component more like a living system, able to maintain itself to prevent slow decay.
I don’t know if you understand my point about the connection between scale and longevity. Or maybe you do since after telling me I am mistaken or biased by experience, you make my point.
There is no conceptual difference between a human gathering matter and energy to repair a bridge, a molecular machine in a cell or a robot on a solar sail orbiting a star. The differ only in efficiency and scale. There is no way for any of them to prevent slow decay without expending matter and energy and the supply of both is finite.
The longevity of Earth’s biosphere is linked to its small relative scale to Earth’s resources. Without breaking the laws of thermodynamics, I don’t see how the relative scale of infrastructure can be disconnected from its longevity. My main point is this, the larger the infrastructure and population in a star system the shorter it lasts at that scale. As far as I can tell, I am basing this point on the known laws of nature, the same ones that inform the conceptualization of hypothesized mega-structures.
I think we are talking about different things. I certainly don’t mean to imply that life has circumvented entropy – it requires an open system to harvest energy and materials to maintain itself. However, life does this automatically – no policy decisions involved. Human activities are based on decisions, and economics results in different problems. the greater the accumulated built infrastructure, the greater the accumulating maintenance needed. This can overwhelm resources (i.e. taxes) to manage the maintenance. The funding shortfall can be due to the economy growing too slowly to meet the maintenance needs (e.g. China, UK) or an outright decline in the economy and tax base (Venice after their high period of banking and trade, and possibly Hong Kong after Chinese acquisition). Life however is always accessing fairly constant sunlight, and growth is limited by energy and material flows. Only disasters like the KT impact can upset the balance.
The analogy with megastructures, like Dyson swarms, should be clear. Build them based on an economic system that requires external funding to maintain them, and they will be subject to decay if not maintained by the system’s polity. Change their maintenance to a self-repairing mode based on their star’s energy output and the recycled resources of their system, and they should last a lot longer and remain functional – arguably as a technosphere that mimics a biosphere.
What resources do you think are “used up” by the biosphere? It is essentially recycling all the carbon, hydrogen, oxygen, nitrogen, sulphur, phosphorus, and trace elements. Yes, some resources are recycled by the planet, and some do get lost for a while, but over long the elements needed for life are just recycled within the biosphere. For example, the biological carbon cycle is far faster than the geological carbon cycle. Yes, there is a huge carbon reserve in the rocks, from the early CO2 atmosphere and the later carboniferous carbon fixation that was buried, but these reserves are not exploited by the biosphere over millions of years. This must be correct as the carbon dioxide in the atmosphere is principally regulated by life, not geological processes, except over extremely long periods.
[Venus lost its water due to planetary heating, and Mars lost its water and atmosphere due to its low gravity, so yes, resources can get lost, but this has not happened to the Earth.]
Earth’s biosphere is continuously transforming mass and energy into waste heat. Given enough time it would theoretically transform the entirety of the planet. Practically speaking, an external force like the expanding Sun will destroy the biosphere before that happens. However, if we remove that element, the biosphere’s lifespan is a factor of its relative scale to resources as stores of work and efficiency. Perpetual recycling violates entropy.
Currency and funding are simply means to facilitate the movement of resources. Conceptually, currency and policy are equivalent to genetic coding for metabolism, with bad policy equivalent to poorly fitting genetics.
To be clear, I am not arguing against long-lived, seld-repairing stellar infrastructure, just the scale.
This statement seems to imply that some fraction of mass is lost to waste that cannot be recycled. That statement needs some explanation. Biospheres tend to fluctuate in mass with teh climate, but AFAIK, overall, biomass is dependent on energy flow with the climate regulating the total biomass. There is no mass loss during resource transformation, just recycling. The recycling is not all biology as some biomass becomes rock after sedimentation and burial, and the Earth’s geology recycles the material.
There is no reason why elements cannot be fully recycled enough given energy.
The difference between human infrastructure and biology is not some “genetic” problem but fundamental to how we build.
Consider a tree and a wooden bridge. The tree fixes carbon and eventually dies. Fungi consume the tree and eventually, another tree will grow from the seeds to fix the carbon released by the tree’s decay. This recycling is at the molecular level. Eventually, the tree replaces itself. Now consider a wooden bridge. If a piece breaks or rots, a new piece has to be cut from a tree to replace the old part. If the bridge is dismantled the wood can be cut and reused, but this has limits as you end up with sawdust. Only biology can produce the wood for building a new bridge or some other wood artifact to replace it. As we build infrastructure parts break or wear out and have to be replaced. The cumulative size of the infrastructure affects the size of the maintenance needed. Unlike the tree that maintains itself through growth, and through the biosphere recycles itself into any form based on the available molecules, our manufactured infrastructure cannot do this. We must either repair using mostly new resources or destroy the broken infrastructure and replace it with something new that we want. The method we build is different. Sculpting columns takes a lot of effort, skills, and information. This is costly. The tree just grows.
Right now, Gaza is being destroyed almost completely. Much of the unique infrastructure will be irreplaceable. Eventually, something will replace what is there, but the particular arrangements of matter that artisans had done will be lost forever. If Gaza was just a natural ecosystem, it would eventually rebuild itself to something approaching its pre-destroyed state after some time.
This is why I say that megastructures would last a very much longer time if they were more like living organisms – self-repairing using the available energy. No extra information or effort is needed, just the ability of self-organizing units to reconstruct themselves after damage or loss of function.
We have started mimicking nature in small ways, e.g. self-annealing concrete. But most of the time we have to expend far more resources to build new parts and install them, whilst nature does this by very different means that does not require specialized external inputs, just basic molecules and energy.
To me, making a “zoo” seems to beg for two reciprocal technologies. First, to watch what is going on, a swarm of tiny antennae (perhaps resembling ordinary graphene “cosmic dust”) that know their positions precisely and detect every frequency of EM, and then do VLBI between all of them to detect all the EM frequencies passing through a large area (such as a Solar system out to the Oort cloud). Such a device might be more sensitive than a SGL telescope that detects light passing only a certain distance from the Sun, and it would look in every direction at once.
Second, the same swarm of probes needs to be able to alter its EM waveforms as needed to broadcast — doing what in a 5G cell phone is called “beamforming”. This should be essentially the time reverse of the first technology. Superimposing a waveform on the light leaving the Solar system would allow aspects of it to be disguised as desired (subject to significant power limitations), . Internally, the same system can be used to censor out unwanted information from the outside. Such deception in either direction seems unfriendly, but in conflict it might hide desirable systems, or at least (if used on every system) to make it hard to tell which ones are valuable or have fleets lying in wait. Censoring the outside world might be a way to avoid having humans put much effort into contacting the friendly berserker next door, just in case they would manage to overwhelm the system.
In either case, the system would not be able to conceal an Oh-My-God Particle, which might simply miss all the probes. Would X-rays or visible light only be concealed if the telescope is small enough that the nearest probe and the source project within the same Airy disk diffraction limit? Though I wouldn’t expect to find anything, it would be entertaining for someone to scan existing images for a signature of imperfect destructive interference in some salacious location.
The zookeeper may choose to, but there is no inherent demand for surveillance with the zoo hypothesis. They could let everyone know about the zoo via an email over a galactic network so no need for warning beacons either. There is no demand for a universal zoo infrastructure protocol either. Just as on Earth, every enclosure could be bespoke. At the risk of bringing UFOs into the discussion, the enclosure doesn’t have to be inviolable. It only needs to be secure enough to never deliver a breach that spoils the zookeeper’s intentions.
Imho, the biggest obstacle to the zoo hypothesis is the lifestyle footprint of the zookeepers and their peers. As long as their lifestyle is below our threshold for observation, and that shouldn’t stretch our belief, they just need to not talk to us.
I Agree with Alex Tolley. A civilization that was one million years more technologically advanced has a space warp or warp drive which immediately results in faster than light communication. Consequently the word colonization is completely obsolete for them. We are chained to the Earth with our primitive liquid fueled combustion chambered rockets. No Zoo hypothesis needed. We are the psychological novices, and initiates and they are the experienced. They are free with the most optimal space propulsion science and we are chained.
We can’t see their heat signature because there is none or not any heat. Their technology is extremely heat efficient like thermonuclear fusion and the knowledge of how to convert one force into another, the unification of all four forces. It’s our primitive technology that has the heat signature. Seeing city lights on a exoplanet 500 light from here is completely beyond our technology today. A warp drive that could go one thousand times the speed of light or faster could get here in less than six months.
There is a flaw in the Fermi Paradox. The idea that because we don’t hear anything or get any ET radio signals, does not mean they are not out there. Remember what Carl Sagan wrote in Cosmos. They might have ethic of non interference with emerging civilizations. If they have survived this long, they have learned to live with themselves. We might be projecting our backwardness onto them. I recall someone already writing in a past Centauri Dreams post something I’ve known for at least fifteen years that the ET’s don’t contact us from nearby, because that would scare us. A show of technological superiority would instantly be implied from such a signal.
This article assumes that a technological civilization always progresses. This is not necessarily true. The Romans knew how to make concrete, a technology that was later lost, and not rediscovered until the 18th century. What if instead of constant progress, the nature of civilization is more like a sine wave, rising and falling endlessly with no particular end result? If so, it’s quite possible that given the constraints set by the speed of light, the crest of the wave is never high enough to result in an interstellar civilization.
The SETI folks have always assumed that interstellar civilization is maintained by em communication – if only to avoid the UFOlogists.If some civilizations remain both technological and long-lived, I see no inherent reason why c is limiting. We have talked about human projects like cathedral building exceeding the human lifespan. Traveling at c, or some fraction of it, would still allow “bubbles” of single-species, interstellar “empires” to exist. While Roman concrete was a technology lost for a long time, much of the rest of its technology seems to have survived.
Interestingly, Vernor Vinge’s A Deepness in the Sky involves a “spider” civilization that lives on a planet with a variable star. Within a lifetime or so, the star cools, the spiders must find deep refuges to hibernate during the cold and rebuild their civilization on emergence. They discover a means to stay awake during the cold period and this allows their civilization to rapidly advance.
While it is quite possible our global technological civilization will collapse and plunge us into a new “dark age” as digital media become lost and with it technology, but I think we could archive enough science and technology knowledge and artifacts to jumpstart the next cycle, one which could exceed ours. Having said that, I am not sanguine that biological humans will be the frontline of interstellar explorers and colonizers, but our machine descendants will be more capable of such travel based on what we already know, assuming no FTL travel breakthroughs.
That’s a good point. The Romans were great engineers, but the Greeks were the scientists of the ancient world. Ancient Chinese tech was very capable and clever, but they never made much of an effort to systematize their knowledge or develop it into a logical structure. MesoAmerican astronomers were highly advanced, but they never used their mathematics to develop physical theory.
Much speculation in SETI seems to be based on the assumption that science and technology must progress continuously to higher and higher levels, building on the foundation of previous successes. Not only do historical circumstances often cause interruptions and backsliding, some cultures may simply reject more advanced science and mathematics for purely practical reasons. For example, you don’t really need advanced quantum mechanics or particle physics to do serious work in biochemistry. You really need protons, neutrons and electrons. And all you really need is Newtonian Mechanics to navigate spacecraft.
Like the Romans and the Chinese, once they were able to build the things they really needed, like arches, concrete, magnetic compasses, ships that could sail into the wind and gunpowder, theoretical science was just a distraction. In mathematics, algebra and and zero were developed by cultures that never applied them to technology. The Romans got along fine with Roman Numerals. And there’s a lot to be said for trial-and-error iteration and numerical analysis techniques.
It might be interesting to see how many cultures simply develop the science they need to carry out their tech, not engage in in purely theoretical work that has no practical application until far down the line. On our own world, scientific method was never formalized until a few hundred years ago, quite recently in our history.
Remember, ETI may not think like we do.
Henri, Your comments are very accurate.
The Egyptian civilization developed precise mathematics for its pyramid constructions, land management and trade, but its science remained PRACTICAL and the Egyptians didn’t develop the reasoning to make science evolve. The same goes for the Sumerians, Babylonians etc. Science was a “tool” in everyday life, but the idea of progression and research was not essential. These civilizations borrowed ideas from their neighbors, sometimes improving on them. The advent of Scripture turned human thought upside down; in a way, by recording facts (cuneiform), it made it possible to transmit knowledge and thus to encourage the conceptualization of things (in addition to mathematics for those who mastered it). That’s probably why the Greeks, on the other hand, turned science into a pure theory and, in the end, no great achievements (I’m schematizing, of course, but the Parthenon is splendid;) We don’t think like our Egyptian or Greek ancestors. (I find all these comments fascinating, but very technocentric and anthropocentric;) Not only does an ETI, if it exists, certainly doesn’t think like us…does it think at all? :)
Quibble: the secret of Roman concrete has been *mostly* rediscovered. We’re still working on understanding how to make concrete as waterproof ( http://www.futureofconstruction.org/blog/scientists-have-cracked-romes-secret-to-waterproof-concrete/ ) or durable ( https://news.mit.edu/2023/roman-concrete-durability-lime-casts-0106 ) as the Romans did.
Happy New Year to everyone and thanks to Paul for all these fascinating topics.
It seems to me that we have not really answered Paul’s question: “can the Zoo Galactic hypothesis be saved? In other words, what could validate it? I propose two crazy ideas (? ) to answer “yes” to this question. Here is the first:
So as not to get too lost, I start from the following principles with the basis of our current knowledge: a) the universe is immense so, statistically, there is a chance that life has hatched elsewhere. b) We consider identical principles in the universe: speed of light; entropy; E=MC2 etc d) we call “life” a biochemical assembly created from simple elements abundant in the universe which, under a certain context, has the capacity to self-duplicate and evolve.
Suppose that the starting chemical factors were the same throughout the galaxy: same compounds everywhere; relative uniformity in the distribution of matter. We also assume the same celestial mechanics everywhere: same rotational movements; of acretion; contractions-ejection of stars etc. (to my knowledge Hubble has not yet shown us a cubic galaxy :) We can then plausibly and statistically assume that the assembly of amino acids which produced life as we understand it, occurred at least twice in the galaxy (50%) instead of just once here…Nature is generous. From this idea, let us imagine that at the same time as the appearance of life on earth (let’s call T1) life also took birth at practically the same time at the other end of our galaxy, on another earth that we will call T2. Same causes, same temporality, same effects. We then assume that our “cousins” have generally evolved like us and have reached a technological stage. Now, let’s imagine a type III ETI which “observes” our galaxy with these two forms of life which develop in parallel. She is neither malicious nor benevolent but neutral. Our type III ETI wants to study the development of the two subjects WITHOUT there being reciprocal influence or intervention on its part. (there is no one else in the galaxy). As T1 & T2 have reached a technological stage, they are therefore [almost] capable of communicating with each other. If this is the case, they will therefore influence each other. From this idea, we can then assume that Type III will “isolate” T1 or T2 through a “zoo”, the time to create a technological or evolutionary gap between the subjects, which will no longer allow an influence of a subject on the ‘other, since one of them will be like “frozen”. The “zoo” hypothesis is saved.
The second response in favor of the zoo comes from questioning the word itself: what exactly are we talking about: a zoo? ; a quarantine or a prison? Three different designs. I don’t believe in the idea of prison or galactic quarantine. I think these are just mental projections of our fears or desires. Why not ! Would a powerful Type III ETI “have fun” putting us in a cage? for which motive ? Are we that dangerous? If we bothered it, I think it would be enough for it to ignore us and concentrate elsewhere or quite simply, to pulverize us; she could easily have the means: a little flick on the sun to make it come out of its orbit and bye bye earthlings :)
Back to the “zoo”. What is a zoo? what is it used for ? In our design, it is a protected enclosure where the species found there are preserved because they are rare and/or endangered. The notion of “zoo” is therefore beneficial.
We could therefore consider that the life that we represent and especially its particular, technological evolution, that is to say the capacity to shape and even leave our own environment, is exceptional in the galaxy; we must therefore preserve it (to educate it? to exploit it? that’s another debate).
Thus, a “higher entity” would be interested in creating this zoo to preserve us exactly as we tried to preserve the small embers of the first fire in prehistory. If we accept the idea that the type III ETI does not want to influence our development, it does not let us know, even though it would probably easily have the means to do so.
Note that if we had proof that we are in a “galactic zoo”, we could almost affirm that we are a unique species and this would answer our eternal question that we are not alone in the universe…that would break the charm, but it would also probably upset the human species: the question has already been asked in the context of “contact”.
How are those 2 enclosures built so that T1 and T2 cannot see each other, yet the universe looks natural, and KIII ETI must also not be observable (as this would also influence T1, T2?
Are the enclosures physical so that eventually an object launched from T1/T2 bounces off the enclosure, or breaks it? Perhaps it is virtual. How big must it be? Does it expand as T1 and T2 improve their capabilities? If the boundaries intersect at some point, what happens then?
Our zoos are more like prisons. The dome in teh Truman Show was made to look like it was much bigger than it was, but tricks had to be used to prevent reaching the edges. Would such tricks have to be applied to the 2 civs?
The Zoo hypothesis is still valid, but with the limitation that it is not intentional by us or advanced technological civilization with interstellar travel. We are chained to our little corner of the galaxy and solar system, but the ET’s with faster than C technology are not. In the distant future, it will our turn to join “the galactic society.” They can spy on us, but we can’t spy on them. This might change in the future if we assume or take seriously we are being spied on by large spacecraft with fast interstellar travel capability. There is infra red telescopes, lidar, and other ways to look for a “mother ship”, than radar. We don’t know what kind of stealth it might have and laser beams between two separate points at a distance if interrupted like those old style electric eye photo cells are hard to foil.
Some commenters appear to believe that our zoos are built for the benefit of the animals. That is rarely true, even today. The claim is commonly used to deflect criticism for what zoos really are: spectacle. Pay your money, come in and gawk at the weird and exotic animals. It’s a business. The animals are often treated poorly (less though nowadays) and lead meaningless lives in a cage. In the early days they were also a display of money and power. It was very difficult and expensive to capture, transport and support animals from faraway lands.
Who’s to say that ET isn’t doing the same (if you can believe the zoo hypothesis), or deluding themselves that they are doing good. Live stream of the monkeys’ latest war of death and destruction coming up at 11!
This strikes me as a very US viewpoint. Perhaps not surprising from the land of Barnum & Bailey.
In Britain, the London Zoo did raise monies from visitors, but it was also an institution to collect animals, do research, and more recently, attempts to stave off extinction of some species through breeding programs. The Royal Botanic Gardens at Kew, while also for visitors, was set up to collect and catalog plant species from around the world. Just this week it notified the public about some very rare new plants that have been discovered around the world.
You can argue whether this was to protect animals or exploit them.
However, the large Safari Parks and nature preserves around the world, most notably in Africa, are designed for the protection of animals, with game wardens to prevent poaching. Trying to preserve rare species is the main purpose of these parks. I would argue this is definitely to benefit the animals.
[The “villains” that purely exploit animals for profit are circuses (waning as attractions), marine theme parks like Seaworld (also waning as the cruelty is becoming more known), and those wealthy sociopaths who hunt big game for trophies – a barbaric activity that should be socially unacceptable. Britain finally banned fox hunting less than 20 years ago, a “sport” of wealthy landowners that also became socially unacceptable. Grouse and pheasant shoots are still legal, but really shouldn’t be. Angling in Britain during the 2nd half of the last century became a catch-and-release sport, with barbless hooks slowly replacing barbed ones. In the US, most fishing is catch and take/eat. Releasing the fish seems like an unknown concept. Perhaps not surprising in a country where hunting is widely practiced in rural areas. /rant]
“very US viewpoint”
I’m not American and mine is not a US viewpoint. Citing one example of a “good” zoo isn’t really a counter-argument. I suggest casting a wider net. Many zoos are doing good work, but how many? There are far too many zoos here and elsewhere that are businesses. They market the spectacle, and for the better institutions the small or large amounts of good work they do.
“Safari Parks and nature preserves”
Those are not zoos. In many cases the tourism money support the preserves. Too many times the marketing and tourism is a cover, at least in part, for illegal or sanctioned resource extraction. It’s unfortunate but there it is.
Please name these other countries whose zoos you have experience of that are just businesses. I named the London Zoo because I have experience of that zoo since childhood.
You can be cynical about Safari parks, but they are for preserving animals. The tourist money supports the program. It is not the reverse.
I mention Safari parks because they are zoos without cages. They are preserved natural areas allowing the animals to interact naturally. Arguably rewilding is a tangential program, and at this point, I haven’t read that they are businesses, just an attempt to reintroduce animals into what was once their natural habitat.
The US has led the world putting business first. Zoos, museums, and galleries that are free elsewhere have become businesses in the US. Publishers want to shut down [still free] libraries. That is why I said that your statement was a very US viewpoint. I can make US viewpoints too, even though my background is from Britain.
Why ask me to name a zoo of that type when you have already done so in an earlier comment (Seaworld)? Maybe we can collect global data on zoos and do some statistics! There are more zoos in the middle, though more towards one side of the scale or the other, but not at the extremes of wholly benign or exploitative. But that’s not the question here, since the topic is the zoo hypothesis.
“cynical about Safari parks”
I’m not cynical about these or about zoos in general. You’re reading that into my words. The parks are better than zoos in many respects since the animals are, to a degree, remain in natural habitat the species is acclimated to. They are businesses to the extent that they must cover their costs by external funding or visitor fees. Many are difficult to support due to human encroachment, hunting, militant activity, and illegal resource extraction.
Reintroducing species to their habitat in other circumstances has an uneven record. Falcons are harassed or killed, wolves are shot by hunters, beaver dams destroyed, animals harvested for food, tigers shot after eating a villager or two, etc. Human civilization ensures that many species and natural habitats are not viable, no matter our episodic good intentions.
So what of ET – what are their intentions with regards to keeping us isolated? Is it for our benefit or do they deceive themselves into believing they are doing good. I would argue that interference is the greater good since they can help us to manage our environment better and reduce strife.
To do nothing is not benign, and possibly evil, depending on how we might interpret their actions. Compare to “clinical equipoise” with respect to trials of medical interventions. It is considered unethical, for good reasons, to knowingly place trial participants in harms’ way.
I find it difficult to believe that any ET would keep us in a “zoo”. I find it easier to believe that they aren’t here at all, or that if they do find us they are more likely either to eliminate us or seek to intervene for the benefit of all. Actions in between these extremes are harder to justify except as a temporary measure until they decide on a course of action.
Your original comment was that zoos are rarely for the benefit of the animals and mainly for spectacle. That was a general statement backed up by what I believe is very limited evidence. Selling tickets for spectacle (e.g. explicitly so in the movie Jurassic Park 2) is a very business-centric, i.e. US viewpoint. Seaworld is a US company and exemplifies this US approach, where the main event is the spectacle, just as in a circus.
The “zoo hypothesis” can have a range of meanings and purposes. Traditional zoos have cages and enclosures to allow visitors to get close to teh animals but be safe. Safari parks, like big ones in Africa, are primarily about wildlife preservation. Exploitation by poachers like any park is deterred to some extent by wardens. Visitors do help pay for upkeep. Rewilding is almost purely about habitat restoration. That populations in rewilding experiments dislike the introduction of top predators is about their attitudes and responses, not the purpose of the project.
All these zoos->parks->rewilding are on a continuum. All could be part of the interpretation of the “zoo hypothesis”. Cages invoke the idea of surveillance, like the Trafalmadorians keeping Billy Pilgrim and Montana Wildhack in Vonnegut’s “Slaughterhouse-Five”. The “zoo” could be more like keeping the earth as a nature preserve, safe from predators (like poachers, snake-oil salesmen, missionaries, arms dealers, or extractive corps.) that is more a “Prime Directive” concept. The zoo could be to keep ETI from harm by us, as suggested by Klaatu in The Day the Earth Stood Still. Clarke was more benign in his short story, “The Rescue”, where the ET civilization saved us, but our relative proliferation meant that humans might overwhelm the ET civilization after 20 years. We could be an experiment, and arguably a spectacle for ETs. But any motives would be unknown to us.
Where we agree is that we both don’t think we are in a “zoo”. I would go so far as to say I think any contemporaneous ET civilization (if contemporaneous has any meaning in space-time) is so distant that they may not even be aware of us, and may not even exist at all in our galaxy.
A lot of objections to the Zoo Hypothesis simply don’t hold water. I have to make the standard denial, that I don’t necessarily believe it, and then I can make the following points:
1. All the comments about the speed-of-light limit effectively say “aliens can’t travel at v > c because we can’t do it with our present-day technology”. That’s not logical. Remember that c is only the most recent of our perceived speed limits (the speed of sound was another such final limit, almost within living memory).
2. The fence-around-Earth objection has a simple answer which is denied but not refuted. Critics say that it would be impossible to enforce a 100% ban on craft coming to spy on Earth. These critics are usually the same ones who insist that UFOs cannot exist ! The possibility that a small number of UFO reports arise from official zookeeper inspections, and/or unofficial snooping, is somewhat wounding to human pride, but could easily occur. On a zoo-planet with less fearful inhabitants, inspections would be quickly identified, but on our Earth the Chinese have used UFO-like balloons to spy on the U.S. (and who knows who else) for years with impunity until now. The odd “real” UFO would not be noticed amongst the “noise” of misidentifications, hoaxes, strange atmospheric phenomena, secret weapons, human spy systems, etc.
‘c’ is not a speed limit; it’s a property of our spacetime. Massless particles like photons are constrained to travel on null geodesics. Massive particles (like us) can travel between objects A and B as quickly as we’d like, if we have the energy required. Any other “rapid” mode of travel will require the discovery of new properties of our spacetime that allow novel connections between spacetime points without violating existing physics.
Possibly. And possibly “existing” physics will be violated.
When people tell me something or other is utterly impossible, and try to invoke science for the proof, I always think back to a copy of Whitaker’s Almanac for, I think, 1946, that I found in my father’s books. In it a professor “proved” that a manned trip to the Moon, even with only one astronaut, was impossible. It took just 23 years for the impossible to be realised.
And when people say that travel at v > c is the real final limit (let’s not argue about semantics), well that was believed to be true for all the others.
If you believe this is an argument about semantics, well, I’ll just have to leave you with your misconceptions. Also, no where did I say “impossible”. Either you fail to understand the topic or what I said, or it’s a strawman. It’s unfortunate that I couldn’t help you to realize your misunderstanding of physics.
Hello,
here’s an original and interesting hypothesis that could be an answer to Fermi’s paradox: the universe would still be too hot for an ETI, which would have put itself on standby until it cooled down => absence of communication and deep time…
https://arxiv.org/abs/1705.03394
I’ve never considered the Zoo hypothesis as any front runner.
It’s strange that the authors Crawford and Schulze-Makuch propose this one as a major alternative.
Life nearly ended up in a cul de sac on several occasions, where life itself during the unicellular and Cryptozoic age ruined the path forward several times and just barely wiggled out of the predicament.
This is the reason Earth got a time span of ~3½ billions of years before anything interesting happened.
On top of that we’ve had 5 mass extinctions, causing a major reset.
If one such would have happened during one of the sensitive periods, Earth might have nothing more than some eucaryotes or procaryotes – and very little else today.
Planetary stability, both as for the orbit, rotation the proximity of a very benign main star are important factors.
So concurrent intelligent life is probably rare on other planets, but IMO not entirely nonexistent.
If any other civ found that advanced life is rare, they will not spend enormous resources and energy on a uni-directional beamer to send unheard messages to the rest of a near empty galaxy.
Our capacity for detecting local radio or laser chats communication and even less, the hum or electronic noise from an advanced civ over lightyears is currently negligible. Not to mention they might be using communication methods we have not yet thought of, or capacity to monitor.
The runner up alternative here is the Dark forest scenario.
And as long as we know nothing, I agree with Stephen Hawkins, lets be very quiet and just listen and monitor until we’re at least have found this alternative to be reasonably unlikely.
Else we might have to deal with Saberhagen-ish berserkers, or the Inhibitors of Reynolds imagination. =)