We live in a world that is increasingly at ease with the concept of intelligent extraterrestrial life. The evidence for this is all around us, but I’ll cite what Louis Friedman says in his new book Alone But Not Lonely: Exploring for Extraterrestrial Life (University of Arizona Press, 2023). When it polled in the United States on the question in 2020, CBS News found that fully two-thirds of the citizenry believe not only that life exists on other planets, but that it is intelligent. That this number is surging is shown by the fact that in polling 10 years ago, the result was below 50 percent.
Friedman travels enough that I’ll take him at his word that this sentiment is shared globally, although the poll was US-only. I’ll also agree that there is a certain optimism that influences this belief. In my experience, people want a universe filled with civilizations. They do not want to contemplate the loneliness of a cosmos where there is no one else to talk to, much less one where valuable lessons about how a society survives cannot be learned because there are no other beings to teach us. Popular culture takes many angles into ETI ranging from alien invasion to benevolent galactic clubs, but on the whole people seem unafraid of learning who aliens actually are.
Image: Louis Friedman, Co-Founder and Executive Director Emeritus, The Planetary Society. Credit: Caltech.
The silence of the universe in terms of intelligent signals is thus disappointing. That’s certainly my sentiment. I wrote my first article on SETI back in the early 1980s for The Review of International Broadcasting, rather confident that by the end of the 20th Century we would have more than one signal to decipher from another civilization. Today, each new report from our active SETI efforts at various wavelengths and in varying modes creates a sense of wonder that a galaxy as vast as ours has yet to reveal a single extraterrestrial.
It’s interesting to see how Friedman approaches the Drake equation, which calculates the number of civilizations that should be out there by setting values on factors like star and planet formation and the fraction of life-bearing planets where life emerges. I won’t go through the equation in detail here, as we’ve done that many times on Centauri Dreams. It’s sufficient to note that when Friedman addresses Drake, he cites the estimates for each factor in the current scientific literature and also gives a column with his own guess as to what each of these items might be.
Image: This is Table 1 from Friedman’s book. Credit: Louis Friedman / University of Arizona Press.
This gets intriguing. Friedman comes up with 1.08 civilizations in the Milky Way – that would be us. But he also makes the point that if we just take the first four terms in the Drake equation and multiply them by the time that Earth life has been in existence, we get on the order of two billion planets that should have extraterrestrial life. Thus a point of view I find consistent with my own evolving idea on the matter: Life is all over the place, but intelligent life is vanishingly rare.
Along the way Friedman dismisses the ‘cosmic zoo’ hypothesis that we looked at recently as being perhaps the only realistic way to support the idea that intelligent life proliferates in the Milky Way. Ian Crawford and Dirk Schulze-Makuch see a lot wrong with the zoo hypothesis as well, but argue that the idea we are being observed but not interacted with is stronger than any other explanation for what David Brin and others have called ‘the Great Silence.’ I’ll direct you to Milan M. Ćirković’s The Great Silence: Science and Philosophy of Fermi’s Paradox for a rich explanation both cultural and scientific of our response to the ‘Where are they?’ question.
Before reading Alone But Not Lonely, my own thinking about extraterrestrial intelligence has increasingly focused on deep time. It’s impossible to run through even a cursory study of Earth’s geological history without realizing how tiny a slice our own species inhabits. The awe induced by these numbers tends to put a chill up the spine. The ‘snowball Earth’ episode seems to have lasted, for example, about 85 million years in its entirety. Even if we break it into two periods (accounting for the most severe conditions and excluding periods of lesser ice penetration), we still get two individual eras of global glaciation, each lasting ten million years.
These are matters that are still in vigorous debate among scientists, of course, so I don’t lean too heavily on the precise numbers. The point is simply to cast something as evidently evanescent as our human culture against the inexorable backdrop of geological time. And to contrast even that with a galaxy that is over 13 billion years old, where processes like these presumably occurred in multitudes of stellar systems. What are the odds that, if intelligence is rare, two civilizations would emerge at the same time and live long enough to become aware of each other? And does the lack of hard evidence for extraterrestrial civilizations not make this point emphatic?
But let me quote Friedman on this:
Let’s return to that huge difference between the time scales associated with the start of life on Earth and its evolution to intelligence. The former number was 3.5 to 3.8 billion years ago, a “mere” 0.75 to 1 billion years after Earth formed. Is that just a happenstance, or is that typical of planets everywhere? I noted earlier that intelligence (including the creation of technology) has only been around for 1/2,000,000 of that time—just the last couple thousand years. Life has been on Earth for about 85 percent of its existence; intelligence has been on Earth for about 0.0005 percent of that time. Optimists might want to argue that intelligence is only at its beginning, and after a million years or so those numbers will drastically change, perhaps with intelligence occupying a greater portion of Earth’s history. But that is a lot of optimism, especially in the absence of any other evidence about intelligence in the universe.
Friedman argues that the very fact we can envision numerous ways for humanity to end – nuclear war, runaway climate effects, deadly pandemics – points to how likely such an outcome is. It’s a good point, for technology may well contain within its nature the seeds of its own destruction. What scientists like Frank Tipler and Michael Hart began pointing out decades ago is that it only takes one civilization to overcome such factors and populate the galaxy, but that means we should be seeing some evidence of this. SETI continues the search as it should and we fine-tune our methods of detecting objects like Dyson spheres, but shouldn’t we be seeing something by now?
The reason for the ‘but not lonely’ clause in Friedman’s title is that ongoing research is making it clear how vast a canvas we have to analyze for life in all its guises. Thus the image below, which I swipe from the book because it’s a NASA image in the public domain. What I find supremely exciting when looking at an actual image of an exoplanet is that this has been taken by our latest telescope, which is itself in a line of technological evolution leading to completely feasible designs that will one day be able to sample the atmospheres of nearby exoplanets to search for biosignatures.
Image: This image shows the exoplanet HIP 65426 b in different bands of infrared light, as seen from the James Webb Space Telescope: purple shows the NIRCam instrument’s view at 3.00 microns, blue shows the NIRCam instrument’s view at 4.44 microns, yellow shows the MIRI instrument’s view at 11.4 microns, and red shows the MIRI instrument’s view at 15.5 microns. These images look different because of the ways that the different Webb instruments capture light. A set of masks within each instrument, called a coronagraph, blocks out the host star’s light so that the planet can be seen. The small white star in each image marks the location of the host star HIP 65426, which has been subtracted using the coronagraphs and image processing. The bar shapes in the NIRCam images are artifacts of the telescope’s optics, not objects in the scene. Credit: NASA, ESA, CSA, Alyssa Pagan (STScI).
Bear in mind the author’s background. He is of course a co-founder (with Carl Sagan and Bruce Murray) of The Planetary Society. At the Jet Propulsion Laboratory in the 1970s, Friedman was not only involved in missions ranging from Voyager to Magellan, but was part of the audacious design of a solar ‘heliogyro’ that was proposed as a solution for reaching Halley’s Comet. That particular sail proved to be what he now calls ‘a bridge too far,’ in that it was enormous (fifteen kilometers in diameter) and well beyond our capabilities in manufacture, packaging and deployment at the time, but the concept led him to a short book on solar sails and has now taken him all the way into the current JPL effort (led by Slava Turyshev) to place a payload at the solar gravitational lens distance from the Sun. Doing this would allow extraordinary magnifications and data return from exoplanets we may or may not one day visit.
Friedman is of the belief that interstellar flight is simply too daunting to be a path forward for human crews, noting instead the power of unmanned payloads, an idea that fits with his current work with Breakthrough Starshot. I won’t go into all the reasons for his pessimism on this – as the book makes clear, he’s well aware of all the concepts that have been floated to make fast interstellar travel possible, but skeptical they can be adapted for humans. Rather than Star Trek, he thinks in terms of robotic exploration. And even there, the idea of a flyby does not satisfy, even if it demonstrates that some kind of interstellar payload can be delivered. What he’s angling for beyond physical payloads is a virtual (VR) model in which AI techniques like tensor holography can be wrapped around data to construct 3D holograms that can be explored immersively even if remotely. Thus the beauty of the SGL mission:
We can get data using Nature’s telescope, the solar gravity lens, to image exoplanets identified from Earth-based and Earth-orbit telescopes as the most promising to harbor life. It also would use modern information technology to create immersive and participatory methods for scientists to explore the data—with the same definition of exploration I used at the beginning of this book: an opportunity for adventure and discovery. The ability to observe multiple interesting exoplanets for long times, with high-resolution imaging and spectroscopy with one hundred billion times magnification, and then immerse oneself in those observations is “real” exploration. VR with real data should allow us to use all our senses to experience the conditions on exoplanets—maybe not instantly, but a lot more quickly than we could ever get to one.
The idea of loneliness being liberating, which Friedman draws from E. O. Wilson, is a statement that a galaxy in which intelligence is rare is also one which is entirely open to our examination, one which in our uniqueness we have an obligation to explore. He lists factors such as interplanetary smallsats and advanced sail technologies as critical for a mission to the solar gravitational lens, not to mention the deconvolution of images that such a mission would require, though he only hints at what I consider the most innovative of the Turyshev team’s proposals, that of creating ‘self-assembling’ payloads through smallsat rendezvous en-route. In any case, all of these are incremental steps forward, each yielding new scientific discoveries from entirely plausible hardware.
Such virtual exploration does not, of course, rule out SETI itself, including the search for other forms of technosignature than radio or optical emissions. Even if intelligence ultimately tends toward machine incarnation, evidence for its existence might well turn up in the work of a mission to the gravitational lens. So I don’t think a SETI optimist will find much to argue with in this book, because its author makes clear how willing he is to continue to learn from the universe even when it challenges his own conceptions.
Or let’s put that another way. Let’s think as Friedman does of a program of exploration that stretches out for centuries, with not one but numerous missions exploring through ever refined technologies the images that the bending of spacetime near the Sun creates. We keep hunting, in other words, for both life and intelligence, for we know that the cosmos seems to have embedded within it the factor of surprise. A statement sometimes attributed to Asimov comes to mind: “The most exciting phrase to hear in science, the one that heralds new discoveries, is not “Eureka!” (I found it!) but “That’s funny…” The history of astronomy is replete with such moments. There will be more.
The book is Friedman, Alone but Not Lonely: Exploring for Extraterrestrial Life, University of Arizona Press, 2023.
Oh, you forgot the most important element in the equation;
How many civilizations exist that have a large moon that exactly covers the sun in Solar eclipses 50% total and 50% annular at this close to a large sun?
It seems to me we as apes seem to think way to much how important we are in a huge universe…
Michael,
Are you implying that the similar angular sizes of both moon and sun (at least, during this period of earth’s history) is something other than just a coincidence?
It almost sounds as if you are implying that some divine Creator (or perhaps a super powerful alien civilization) deliberately engineered the moon’s orbit to give us a hint that we are somehow “special” in His or its eyes.
Indeed, it seems to me we as apes seem to think way too much how important we are in a huge universe.
The point being no, but to “Bayesian statistics”. This should be added even though we do not know how common large moons are around close in planets to large stars. This will become available as the next generation large telescopes and space born telescopes and interferometers are built.
I have always looked at it in 3 ways:
1.Religious.
2.Aliens.
3.Statical Probability.
But my preference, being number 3, is which in all probability means intelligent life is very common in our galaxy.
I’m not sure I follow your logic, but I’ll let it go at that.
While the OP must have been sarcastic, s large moon / satellite might be an important factor for stabilizing a planets axis, so that it do not tip over repeatedly causing severe climate conditions – even in extreme cases having a ½ year dark winter while the other hemisphere getting deep fried.
Mars is thought to have such a wobble, though not to any extremes
.
A large moon will also prevent a life bearing planet from getting bound rotation in case it’s located near a relatively quiet red dwarf star such as Lalande 21185, Lacaille 9352 or extremely close in as is the case of Teegarden’s star.
Besides that I agree with the author: “Life is all over the place, but intelligent life is vanishingly rare.”
And there’s two factors in the Drake equation that’s missing – and those are.
1: Life get started, but the world where life arise be on a planet / world where the environmental conditions will not permit advanced life to develop.
(Deep water pockets on worlds like Triton, Pluto or Enceladus. Or the howling jetstreams on a warm mini Neptune. Microbial life might exist, but will be stuck without any upward path even if they get placed around a star that last a hundred billion years.)
2: Life get started, but get whacked before getting anywhere. Mars and Venus are analogues for such a scenario.
And if we truly are alone, then yes we apes probably underestimate just how important we are, being the only ones who can see and understand the universe as it is.
Hello Paul
Thanks again for a very thoughtful and productive essay. As always I see things a bit differently after reading your work. Wonderful .
In return may I suggest , somewhat tangent to your article, Otherlands, by Halliday ?
https://www.amazon.com/Otherlands-Journeys-Earths-Extinct-Ecosystems
His writing is some of the most elegant prose in a long while , reminding one of the young Loren Eiseley ….who’s comments on lonely , alone are, as you know ,
Insightful and profound .
Thanks again
Interesting title, Mark. Thanks for the recommendation.
The Amazon address came up with they could not find the page, so I did find the correct link and downloaded the Kindle version! It looks to be very interesting.
https://www.amazon.com/s?k=Otherlands-Journeys-Earths-Extinct-Ecosystems
If we can explore worlds in VR, I am not clear how the relatively low-resolution images from the SGL will help. It would make “Minecraft” look hi-res. Unless there is some way to increase the resolution (isn’t that determined by the effective diameter of the sun?) the exoplanet images will be poor, best suited to determining the geography and conditions of an exoplanet, including its life. I think the images of Mars prior to the Mariner flybys as the best model for what the SGL can offer.
IMO, Friedman is still stuck in an earlier period of technology with his reference to human crews and robotic probes. He really needs to think about “crewed” as embodied intelligence, possible at the [sub-]human AGI or super-human higher level of intelligence. While the mission times will still be daunting from a human lifetime, they will be perfectly OK for machine intelligence that may be effectively immortal. A Solar System intelligence directing its intelligent avatars to exoplanets will likely prove the best exploration method and will allow all [interesting] exoplanets in the galaxy to be explored. Whether these machine intelligences will have the same interest in life as we do is another issue.
If this argument is sound, then, the lack of obvious von Neuman replicators in our system, is further evidence that expansive (“grabby”) technological ETI has not emerged in our galaxy at any time in the past. If it had, the machine intelligences that ultimately supplanted them would have an enormously extended technological lifetime. [Although this assumes that such a machine civilization is not self-destructive.] At present, even our most rudimentary narrow AIs require huge computing power. However our own brains are proof of principle that much smaller, low energy-consuming intelligences are possible, and insect-level intelligence is borne in truly minute brains. When equivalent machine intelligence will appear is unknown, but I would guess well before any human could leave on a mission to an exoplanet.
So use SGL (and other) technology to remotely explore the nearer exoplanets, but then send out intelligent machines to reach the more interesting exoplanets. If we are not around to receive their data, then “Skynet” will.
None of the above should stop the SETI. Continuous all-sky monitoring across all wavelengths would be ideal, as well as looking for other technosignatures. But maybe we are limited to using the equivalent of smoke signals and semaphores in a world of radio and optical laser communication.
Alex, I believe you are a biologist, so I’ll address this comment to you. I question the idea that life is common in the universe. As I understand it, life got started once, and only once on Earth. This seems weird. It seems to me that once conditions were right, life should have started more than once. If all it takes is sunlight or heat prodding complex molecules to replicate, this should have happened anywhere on Earth where the combination of energy and molecules was right. And yet apparently it only happened once. In fact I believe the latest theory is that all life alive today is descended from a single cell (which presumably was created by a replicating molecule.) https://www.nationalgeographic.com/adventure/article/100513-science-evolution-darwin-single-ancestor#:~:text=All%20life%20on%20Earth%20evolved,more%20than%20150%20years%20ago.
So if in 3.5 billion years, life only started once on Earth due to a single replicating molecule, IMO this implies that all life, not just intelligent life is quite rare. Also the fact that we have found nothing on Mars, no fossils, so single cell organisms, absolutely nothing, even though Mars had conditions favorable to life 3.5 billion years ago just like Earth did. So is it true we are all descended from a single cell? And if so, doesn’t this probably greatly decrease the number of planets where life might have evolved?
P.S. Also biochemists have been trying for at least 70 years to create life in the laboratory and they haven’t succeeded. This also suggests that life is extremely rare. If it was just a question of combining energy and molecules in the right way, I think we would have succeeded in doing it by now.
All life that is extant today can be traced back to a hypothetical cell called the Last Universal Common Ancestor. However, this does not mean that there were other lineages that subsequently went extinct. For an analogy, we can trace all female humans to an “ancestral Eve” but that doesn’t include other Homo lineages (e.g. H. neaderthalensis) etc.
Obviously, the LUCA cell was far too complex to just emerge very quickly, unless one wants either delivery from elsewhere or divine creation. It was preceded by simpler cells, and pre-cellular forms. Some scientists are pursuing the idea of a shadow biosphere of life that is different from that we know of.
There are many theories about abiogenesis, but the fact that life doesn’t spontaneously emerge easily from experiments doesn’t mean that is must be exceedingly rare, just that the conditions need to be right and enough time provided.
Mars is likely sterile on the surface due to the radiation and UV. The resulting [per]chlorates are highly toxic, not unlike peroxides. However we have not looked below the surface this is the mission of ExoMars that will analyze samples 2 meters below the surface. As we know there is a subsurface biosphere in the crustal rocks on Earth, so there might be on other planets. I wrote a post on this blog about that Radiolytic H2: Powering Subsurface Biospheres. [But bear in mind that inhabitable =\= inhabited.]
The counter argument to life being rare is that it seems that life on Earth probably sustainably appeared soon after the surface became inhabitable, indicating that if it was due to local abiogenesis, that happened quickly. It also doesn’t rule out multiple starts that were subsequently eliminated by sterilizing impacts, or even by more successful forms.
But the fact is that we just don’t know. It may be common or it may be very rare, or even that life is unique to Earth. We will know if we find life in the solar system that is from a separate abiogenesis, or an unambiguous biosignature on an exoplanet. Just one example would indicate life on Earth is not unique. A catalog of exoplanet biosignatures would indicate life is common in inhabitable worlds. Data will determine which idea is correct. Now it is possible that all life has a common origin. If so, that would create a whole new set of questions about its ubiquity. That commonality will be hard to prove without getting samples of this life, a prospect for the future when we can send interstellar missions.
“Friedman argues that the very fact we can envision numerous ways for humanity to end – nuclear war, runaway climate effects, deadly pandemics – points to how likely such an outcome is.”
No, not really. The argument assumes that these are mutually independent, and that a calamity is 100% ‘effective’ rather than slightly less.
Human caused calamities are really all manifestations of a single underlying cause: our untamed animal instincts. Advances in our civilization and culture will gradually tame most of it. The question is whether it will or can happen quickly enough. If not…
While 99.9% destruction is catastrophic it does not mean the end of humanity. Even if it takes 500 years for a recovery to take hold that is nothing in the context of deep time. We may fail to pass the test many times over the millennia but if we pass the ‘filter’ once, that bodes well for the longevity of humanity, and therefore for our likely human-created successors.
Pessimism is too easy.
The problem with “recovery” from a deep collapse is that we have largely strip-mined the resources needed for recovery. I could see recovering the metals from the artifacts we constructed, and, like the Britons after the Romans left, reused their stone for building. But fossil fuel energy sources will be gone. The induced climate change might also make agriculture difficult. Recovery to a state even at a pre-Industrial revolution level might take thousands of years, and possibly may “never” become an industrial civilization again. Never say never, but our lack of sustainability means that if our civilization collapses, recovery to a similar level may not be possible. That future civilization may be trapped in a Malthusian state with no way to escape it. This civilization and its future may be our one chance. No “backsies”. Maybe a few million years from now, there will be a full biosphere recovery and our evolved human descendants can make another go of it. But what is a few million years in deep time…
Alex Tolley beat me to it re: the difficulty of recovering from collapse, but I’ll add this quote from Fred Hoyle:
“It has often been said that, if the human species fails to make a go of it here on the Earth, some other species will take over the running. In the sense of developing intelligence this is not correct. We have or soon will have, exhausted the necessary physical prerequisites so far as this planet is concerned. With coal gone, oil gone, high-grade metallic ores gone, no species however competent can make the long climb from primitive conditions to high-level technology. This is a one-shot affair. If we fail, this planetary system fails so far as intelligence is concerned.”
As for human-caused calamaties all being the product of “animal instincts”, which “advances in civilization in culture will gradually tame”, this strikes me as wishful thinking. Many of our “advances” are surely a product of our animal instincts too. Look at the rapid technological advances that can occur during wars; do you think all those developments in jet aircraft, rockets, computers, radar, nuclear power, etc. would’ve happened so quickly without World War? Would Apollo have happened without the Cold War?
Here I’m reminded of some other quotes, by Friedrich Nietzsche:
“Man needs what is most evil in him for what is best in him.”
“The tree that would grow to heaven must send its roots to hell.”
“Be careful, lest in casting out your demon you exorcise the best thing in you.”
There’s no progress with a tamed humanity; there’s no surviving either. Pessimism may be easy, but so is moralism.
There are lots of assumptions doing heavy lifting in both of your replies. ‘All’ is a big big word. And why the belief that a future human civilization will make the exact same mistakes as ours, or that our path is the only one to building a technological civilization? In fact, we already know how to do better, but we choose not to because it’s inconvenient.
I think you need to re-examine your assumptions. Quoting a famous person repeating those assumptions does not elevate them.
Perhaps you should offer this alternative path to technological civilization, and show how it avoids requiring the resources we gave use up. (It would make a good post, IMO).
What do you mean? Alternatives to fossil fuels and various structural materials, elements/ores certainly exist. Even were there no alternatives in select cases, not ‘all’ of the resource will have vanished. None of this requires an article since I have nothing novel to offer that isn’t already known.
Our economic and political systems make certain paths easier than others. Necessity will carve other paths. For example, removing the reliance on cobalt for high efficiency batteries. We have difficulties in shifting our way of doing things because disruption can be difficult and expensive compared to what is prevalent and what we depend upon. For example, transitioning from fossil fuels. It’s easier to choose the alternative at the outset. Again, none of this is novel.
I think you are wrong. The key to getting us out of the Malthusian trap was the harnessing of more powerful energy sources. Prior to combusting coal, there were few choices – animals, wind, water, and wood burning. All of these were limited, Animals needed a lot of food and were limited in output. Both wind and water were relatively immobile sources – think windmills, waterwheels, and for boats, sails. Wood combustion was relatively limited as it could only be replaced with time. England was almost deforested by the charcoal burners. The liberating energy source that had high energy density, was coal. It was relatively abundant and was a store of millions of years of fossilized carbon. But to harness that energy, there had to be metals, notably iron and later steel, plus some precision engineering. Watt’s steam engine was the breakthrough technology. But we have exhausted the easy-to-acquire coal and iron sources. Without mining, iron is hard to acquire.
Our industrial civilization leveraged these technologies to eventually acquire other energy harvesting technology, yet we are still reliant on the combustion of fossil fuels for power, and ever more advanced mining technology to extract metals. Without those easily required resources, we could not get to where we are today. It should also be noted that the Industrial Revolution started in England. Older civilizations like China and India failed to develop that technology. The rest of Europe followed. It is just possible that we had a lucky cultural accident that may not be repeatable.
If you think there is an alternative path to get to an industrial civilization that can be used to create a rich, post-industrial one, then you should spell it out because, because AFAIK, there is no viable path without the mentioned resources. Restarting our level of technological civilization will not be possible. It can reach pre-industrial levels, although even reaching the bronze age will be impossible without copper and tin resources, which were exhausted (Cornwall being the main source of tin in ancient times) and cannot be replenished.
You don’t have to write a word – just point to work that shows how a new civilization can bypass the metals and fossil fuel period to develop energy systems that can be harnessed to produce food and allow the bulk of the population to escape subsistence farming and build the technical skills to jump-start our civilization. I know of none. So if you know of them, point them out. No pocket end states, a viable path to achieving that end state has to be shown.
An essay on Aeon making my point differently: Out of the Ashes.
You continue to assume that a future technological civilization will behave exactly like ours. I would hope and reasonably expect (but no one can prove) that a few lessons will have been learned. I am not responsible for supporting a scenario based on your unwarranted assumptions.
By eliminating a large part of our wasteful behavior, including personal transportation and consumerism, the available power and material resources will be far less strained. Other resources scale with population, so the future population will likely plateau at a far lower level.
And if not? Boom! On to round 3 (etc.). Or maybe not. It certainly won’t get easier.
In the SF stories of the 1950s, a “supercomputer” was the size of an office building, with Niagra Falls or more needed for cooling.
In 2015 I bought a smartphone that had a million times the processing power of that fictional supercomputer, fit in my pocket, and was cooled by ambient airflow.
That’s 60 years of technological advance. how much longer to where we can actually build megastructures? By the time we get there, a Dyson Sphere may look as quaint as that office building under Niagra Falls.
There are a lot more reasons for us to observe “the sky is not covered with Dyson Spheres” besides “no civilisation capable of contructing them has ever arisen”.
@Christian
While some of our technologies have rapidly improved in power and miniaturization, technologies that must house and transport us, cannot be reduced in size as we, as evolved biological organisms, cannot. We need living space. So if we want to increase our energy use and living room, we have to expand into space. The most efficient way is to build habitats and energy-harvesting in space, with the limit being utilizing the energy output of a star.
The only other alternatives are to maintain a low population or miniaturize the population. Arthur C Clarke’s solution for both was the City of Diaspar in The City and the Stars. The usual Malthusian 4 horsemen could reduce the population, as was feared in the 1960s with Ehrlich’s The Population Bomb. A technological solution is mind uploading (The Rapture of the Nerds) which the Singulatarians seem to hope for.
Of the alternatives, I think I prefer space habitats. However, once the output of a star is fully utilized, what then? Even interstellar migration is limited by the speed of light and the finite size of the galaxy.
First of all, let me remind you all the “Population Bomb” rhetoric either is ignorant of or deliberately ignores the demographic transition. (Points at Japan)
Second, as far as increasing energy use goes, see above re: increased efficiency allowing smaller and more powerful devices.
Third, I’ve grown increasingly skeptical about O’Neill-style colonies – I think we’re going to have to export entire ecosystems to wherever we colonize. It’s not impossible but we’ll need a much better level of ecological understanding to design them to not wreck the habitat.
Are we going to have off-planet outposts, and then self-sustaining communities? I think so, but system-wide colonization and exploitation is way off in the future, and we can’t predict what theoretical and engineering advances will be made between now and then.
We know our knowledge of what is scientifically and technologically possible is incomplete or flat-out wrong. Making categorical statements about the Universe based on incomplete knowledge is, to put it mildly, dubious.
@Christian G
I am not sure what your critique of Population Bomb is. AFAIK, it failed because of the “Black Swan” of Borlaug’s “Green Revolution” that vastly increased crop yields (although we are now starting to see the price of this too). Be that as it may, we did stave off the mass starvation due to overrunning Malthusian limits that Ehrlich predicted. There were similar critiques of the famous “Club of Rome” models that Herb Simon suggested would be offset by technology. Ehrlich famously bet against Simon and lost, although he then claimed he bet on the wrong things that were not substitutable, e.g. potable water.
I tend to be skeptical of the O’Neill colony concept too. There was too much breezy assumption that ecosystems could be taken up into a tin can. Yes, the beautiful paintings of the interiors by Davis and Guidice that were more like parks and gardens that were assumed to be tended like house plants were a bit of a mirage. We really don’t know if a piece of Earth isolated from the rest of the biosphere can work. I guess that it may prove somewhat ephemeral. The best model I have is not the failed Biosphere II, but the palm greenhouse at the Royal Botanic Gardens at Kew in London, notably the greenhouses. I haven’t seen it, but the Eden Project in the south of England might be an even better model.
There is, IMO, a more logical reason for human colonies to not be viable, despite the dreams of some. Assuming we have near-instantaneous travel, then where do the passengers go? To mining outposts that are the space equivalent of sea-based mining rigs, or the bases in Antarctica? Not great destinations and the personnel rotate. But we don’t have that rapid travel. It is a long slog even to Mars, let alone to the outer planets. The crew of Clarke’s Discovery would be fried by radiation in Jupiter space if they went to Europa (although Saturn’s Iapetus would be a lot safer), all the while living exposed to the radiation risk even for the most stoic passengers living onboard.
But if those bases and energy-harvesting facilities are run by intelligent machines, already capable of living in space, no biosphere needed, then that is where a post-human civilization will live. I think Baxter and Reynolds have it right about the machine AIs in The Medusa Chronicles, just not about the human expansion into the Solar System.
“Some circumstantial evidence is very strong, as when you find a trout in the milk,”
Henry David Thoreau, 1850.
My opinions are pretty clear, I’ve listed them here before, (“A SETI Reality Check”, 3 July 2000). I’ll concede my evidence is wholly circumstantial, but there it is.
I suspect that there are, at most, only a handful of intelligent species in the Galaxy right now. One for sure, but probably not much more. My reasoning is based on the following:
1) Life is common, as suggested by how quickly it arose on earth.
2) But multicellular life is rare, as suggested by the fact it took billions of of years to
arise on earth after life arose.
3) Intelligent life is not as rare (given it only took a half billion years to arise here
after multicellular life appeared) but it is so recent and explosive in growth we
really cannot evaluate its long term characteristics or potential. We certainly
cannot say it is inevitable, or even of any survival value.
4) We cannot say whether intelligence and civilization inevitably leads to
interstellar travel or communications.
Like I said, my evidence is purely circumstantial. I hope I am wrong. But my instincts and intuition tell me there are at most only a handful of technical civilizations in the galaxy right now, perhaps only one. And I trust my instincts and my intuition.
So, how much is “a handful”? That is why we are all here, isn’t it?
I find myself somewhat more excited by the prospect that our galaxy is our oyster than the prospect that we are sharing it.
Selfish or shellfish? – you decide!
Humans believe all sorts of nonsense. This belief can happily sit where the gulf of ignorance is large. The fantasy of Star Trek and innumerable movies has probably pushed the needle of belief in the direction of ETI, perhaps looking very human with minor facial or anatomical alterations. But we just don’t know.
As for wanting to talk to other people, a sizable fraction of the human race wants nothing to do with slightly different humans (skin color, religion) and will happily slaughter and enslave them. This, even today even in the richest nation on the planet. But we “talk” to our gods, our pets, and even our dumb machines. Now we can get actual verbal responses from primitive AIs, whether by text, voice, or attached to virtual girlfr…err,…people. Are we, as a species, really interested in talking with aliens, even those as friendly as Klaatu or Spock? [We claim we want to talk with cetaceans, but we keep slaughtering them, anyhow.]
There is an old joke: “Join the army, travel to interesting places, meet new people…then kill them.” If we could travel to the stars, and find lo-tech civilizations, would we really respect them and leave them alone, or would we insist on “understanding” them and then exploiting them? Not all of humanity, just the sociopathic elements intent on gaining wealth and power.
If the galaxy is full of life, from mostly microbes to a fraction of worlds with complex forms, there is a lot to explore. If the galaxy proves sterile apart from Earth [IMO, unlikely], then there is a possible goal, even responsibility, for humanity to “green” those worlds and spread life.
Randomness and chaos in many fields can and does lead to spontaneous emergence of order. One field in which it manifests is biology and its daughter disciplines.
At the molecular cell biology level, there is a continuum from the abiotic to a sufficiently organized system of molecular assemblages that meets the imperatives for survival, growth and replication. Also essential is a fence, a cell membrane, to keep its systems together. At each stage of further organization, appropriate fences are a sine qua non. Without cell membranes between cells, one has plasmodial slime mold, a mass of cytoplasm with multiple nuclei. At higher levels of organization there are skin,burine markers, fences, walls, or their mutually agreed equivalents.
Intelligence is the result of an entire series of fortuitous steps in the case of biological organisms, even though it can be viewed as a extension of the continuum from abiotic to biotic. It involves a host of social factors beyond just biology.
Organization at higher levels requires interaction between individuals and groups of individuals. This is essential for technology. Many species are solitary, including some insects, most large felids, etc. and solitude is a way of life with them.
Humans being a social species, solitude is an exception. However it is not a problem for those with an awareness of the Self; awareness without an “of” is the nearest one can get to awareness of the Self.
One can delight whether in solitude or in company.
Imagine that Alpha Centauri had life, we cannot even fully characterize its planetary system yet, so it may be sitting right under our nose.
Conversely, there literally may be nothing else out there.
That’s a pretty extreme range of possibilities.
The answer to is there anyone out there, is why aren’t we a spacefaring civilization, yet.
It’s possible we can’t be, or it’s possible we won’t be.
Extinction is what happens if not a spacefaring civilization.
Of course being a spacefaring civilization might not be enough- but at least there is some hope or a reasonable chance we could not go extinct.
And our up coming global population collapse, probably more of serious a threat as compared to global nuclear war.
Found this on Wikipedia, could be the reason the Drake equation is caught in frequentist interpretation.
“During much of the 20th century, Bayesian methods were viewed unfavorably by many statisticians due to philosophical and practical considerations. Many Bayesian methods required much computation to complete, and most methods that were widely used during the century were based on the frequentist interpretation. However, with the advent of powerful computers and new algorithms like Markov chain Monte Carlo, Bayesian methods have seen increasing use within statistics in the 21st century.”
Giving AI or Quantum computers enough training on just what we know about moons in our own solar system may give us a better perspective on this probability model…
@Michael Fidler
The difficulty with Bayesian methods is the prior probabilities. They need to be acquired in some way, otherwise they are guesswork. Given the data to build those prior probabilities, then Bayesian methods can work well. But if the data is limited, or unavailable, they fail to be useful. They are used in machine learning models although I haven’t found they work better than other methods.
Well, we do have a database of moons that are large compared to the main object that could be used to give an idea just how rare total solar eclipses may be. The problem is we would be looking at the earth moon system as a large asteroid binary! :-} We have plenty of dwarf planets with large moons and that extends all the way down to the smaller asteroids. Every other “planet” is huge compared to its moons in our solar system, but to have a database for the Bayesian methods that may be enough to see if this may be common basis for small worlds. The dwarf planets and asteroids could be compared both at our 1AU distance and also by planet to moon size and relative distance between the moons. This would be something that can be done now and would not require anything more then the current database…
@Michael Fidler
Isn’t our moon an anomaly in that it was created by an impact with a “Mars-sized” boby (Theia?) that ripped off a chunk of the Earth’s mantle which combined with the debris of the impact, resulting in a large moon? Is this really the same model as binary asteroids or Kuiper Belt objects? AFAIK, there are no binary moons in the System (not stable?).
It is certainly true that life on Earth has adapted to the effects of a large moon, both its gravitational effects on tides that are greater than the solar tides and interact with them, the frictional effects of slowing the rotation speed of the Earth, and the brightness of the full moon to time spawning and other behaviors. Life on Mars would not have had those phenomena with the tiny moons Phobos and Deimos.
But the Moon has increased its orbit around Earth over time, being much closer in the past and therefore more potent both gravitationally and as a varying bright object in the dark sky. Cellular clocks evolved when it was closer which may be why some clocks when not entrained by the length of our current 24-hour day run closer to 16 hours. Earlier life with eyes would not see eclipses as we see currently see them, as the moon would fully occlude the sin, rather than closely match its size. What we see is purely a chance of our emergence in evolution. Our primate ancestors tens of millions of years ago would have seen a larger moon, and this would be even more obvious to the Permian amphibians. I see no special reason for what is a coincidence rather than some [implied] design. Thinking otherwise is akin to seeing something significant in random patterns, and studied as numerology and other pattern interpretating ideas.
We are talking about celestial mechanics and nothing more. The idea that this relates to just the earth moon system shows the basis in our thinking and how unique it is only upholding the earth centered universe. Sorry, but your argument is lost in our self centered attitude that we are the only intelligent life in the universe. Celestial mechanics is completely unbiased and has nothing to do with numerology. The inclusive of these smaller objects in a database for the dynamics of such systems would only help to improve our perspective of what may be in other exoplanet systems. Gravity, orbits and mass has nothing to do with humans but I’m afraid your bias does…
AFAIK, there are no binary moons in the System (not stable?). What are you saying? Some of the dwarf plants have large moons, Pluto and Charon being a prime example. Fifteen percent of the asteroids are binary, that’s one in every seven asteroids have a moon or two. That is 150,000 binary or more asteroids many of which have a relatively large moon size to the primary. This is a huge database to see just how common these ratios may be. Your own belief that the earth is unique shows how little we really know…
@Michael Fidler
I accept the Pluto Charon pairing, although when I said no double moons I was referring to a doublet moon orbiting a planet. For example, none of the moons orbiting a planet from Mars to Neptune are a pair of moons with a barycenter rather than a single moon. It was this situation that I was querying as regards stability. Asteroids are not moons, neither are the Kuiper belt objects.
https://www.johnstonsarchive.net/astro/asteroidmoons.html
As a paradox, the Fermi question implies a volume of space that could include hundreds, thousands, or millions of galaxies. The solution of N=1 for the Milky Way does not provide a robust answer. If expansionist traits are exclusively loud and grabby, we need need values for the Drake equation to deliver N=1 for the maximum size of the “Fermi question volume”. If the expansionist traits of loud and grabby are only dominate or possible, we don’t have a paradox.
Imho, the insistence that the Fermi question is a paradox emerges from the emotional satisfaction provided by winning an argument or discovering a definitive answer. There is overwhelming evidence that humans do not need the winning argument or the definitive answer to be true to experience emotional satisfaction. The desire for galactic, “Fermi volume” manifest destiny and/or to be the most intelligent species in the galaxy is also emotionally motivated.
The notion that N=1 is more rational than N=2+ is suspect. It requires either unfounded confidence in the ability to predict exclusive traits for expansion or the irrational assumption that the possibility of a trait appearing within a finite space is equivalent to a trait appearing. If we accept that expansion and deep time select for fitting traits, Friedman’s assumption that expansion is difficult or impossible for biology makes this assumption, ETI will converge on similar traits and N could have a high value. The equivalent for a streamlined body shape for aquatic animals could very well be sufficiently quiet and selective to fall outside our ability to see.
It’s not possible to predict what will happen next year, let alone a hundred or a thousand years in the future let alone deep time, as far as humans are concerned. Take two different outcomes in one country for example. In one outcome Biden wins the next election, in the other Trump wins. What will that one event do to the future of mankind? Another example: Russia wins the war against Ukraine, Putin is strengthened and invades another country. Seeing this success China invades Taiwan. How does this affect the future? Think of the non-renewable resources we commit to advanced methods of war. The future lies in drastic changes in human behavior to allow rapid de-carbonization, rapid population decline, and new ways of dealing with human problems not involving mass murder in various guises. Can we do it? Are we even trying to do it? I leave that to my fellow readers to decide.
The difficulty of space travel depends mostly on the time involved. If Alpha Centauri mocks us as the measure of our troubles, then Omega Centauri is evidence of what could be accomplished — as it may have originated from Gaia-Enceladus, a galaxy which collided with our own. In particular Kapteyn’s Star, a halo star just 13 light years away, may have originated with that globular cluster … and if intergalactic material has blindly come so close to our doorstep, why should we doubt that some nodule of matter from another galaxy is hidden away in our own Solar system, even within our own terra firma? And if rocks might possibly travel from other galaxies to land upon the Earth, surely it is possible humans will one day travel to another galaxy, and presumably first to other stars, whether in slow time by gravitational interactions or faster via some more deliberate means? The only question, and it’s a doozy, is whether our species can possibly survive for hundreds of years, let alone hundreds of millions. Sedna already looks like a slow interstellar spaceship – can our people colonize it and survive to see it launch?
Random late-night thoughts on the universe
Dark Energy. The phenomenon of pushing matter apart in the universe appears to show increasing velocity between the galaxies over time. We don’t know what it is, just observe its effect.
Using the balloon model of the universe, with teh galaxies as points on teh surface, we see galaxies moving away from each other as the balloon expands. As we look further into space and back in time, the expansion is slower than we see locally.
We assume this is a global phenomenon. But what if it is local, acting more like a field with its center somewhere in the local cluster of galaxies? The greater strength at the center near us, and weaker going outwards would appear to teh observer [I think] the same as if the effect was global and changing over time.
Is this idea an artifact of the model I used, and is it consistent with observation? Is the idea falsifiable?
We assume [as we should] that dark energy is a natural phenomenon. But what if it is artificial? Imagine if it is some effect of agency. Like global warming due to CO2 emissions from fossil fuel energy. Or a side effect of space flight, like the contrails of aircraft and increased cloud cover. Is it deliberate, perhaps an attempt to keep a spreading distant predator or phenomenon arriving as far away in time as possible? Or perhaps a deliberate attempt to avoid an oscillating universe.
Dark matter. Are dark energy and dark matter in some way connected? Dark matter, AFAICS, only interacts via gravity. It tends to clump with ordinary matter. It was first detected by the anomalous rotation of stars in galaxies that was not what would be expected from the visible matter alone. It is also coincident with the large-scale structural distribution of galaxies.
What if the clumping of dark matter with matter creates voids, allowing dark energy to have its opposite, “anti-gravitational” effect? Is the amount of dark matter constant, or is it constantly being created with the associated creation of dark energy – rather like the separation of a mixture into its 2 components? Is the rotational structure of old galaxies the same as with younger ones, implying that either dark matter is being created, or increasingly clumping with visible matter? This model would suggest that clusters of galaxies will separate less fast due to dark energy than predicted, whilst the separation between clusters will be faster. The difference might be subtle after taking into the effect of gravitation of both visible and dark matter in galactic clusters. Has this been examined, and are the observational error bars small enough to detect such a model?
If we ever get to explore the galaxy, I suspect we will find artifacts and relics of long dead civilizations on airless moons and planets (where they can be preserved for long times) everywhere.
Should we not take into account that the universe and our galaxy in it may have only progressed to a time, recently, that could support life and the intelligence it brings?
Except that we know of planets billions of years older than Earth. Doesn’t mean they have life, but their existence means there may be many ancient exoworlds that do have life, perhaps more evolved than ours. Add in the fact that almost every star has its own solar system and the odds are only increased.
See here for a few examples:
https://www.sciencenews.org/article/oldest-solar-system-unearthed-kepler
https://www.oldest.org/geography/planets/
Aren’t there more factors to habitability? like suns that don’t flare up too often, or even a cosmic neighborhood where the star groups don’t have too high a cosmic ray background preventing life from forming, or even having stars close by that don’t go nova all too much.
From the essay:
“Bear in mind the author’s background. He is of course a co-founder (with Carl Sagan and Bruce Murray) of The Planetary Society. At the Jet Propulsion Laboratory in the 1970s, Friedman was not only involved in missions ranging from Voyager to Magellan, but was part of the audacious design of a solar ‘heliogyro’ that was proposed as a solution for reaching Halley’s Comet. That particular sail proved to be what he now calls ‘a bridge too far,’ in that it was enormous (fifteen kilometers in diameter) and well beyond our capabilities in manufacture, packaging and deployment at the time, but the concept led him to a short book on solar sails and has now taken him all the way into the current JPL effort (led by Slava Turyshev) to place a payload at the solar gravitational lens distance from the Sun. Doing this would allow extraordinary magnifications and data return from exoplanets we may or may not one day visit.”
For those who want to learn a bit more about the heliogyro space probe concept, see this article:
https://www.drewexmachina.com/2016/03/06/the-missions-to-comet-halley/
As to the question of where are the ETI, this essay and its book subject just demonstrate once more how much we need to really ramp up SETI in multiple forms and with more adept instruments. Nice to know we can at least add to this plan some actual possibilities for starting to reach nearby star systems to search directly for extraterrestrial life. However, until then, we won’t know if we have any interstellar neighbors unless we get very lucky. We have to search.