The Fermi Paradox: Absent Megastructures
This video is sponsored by CuriosityStream. Get access to my streaming video service, Nebula, when you sign up for CuriosityStream using the link in the description. In an ancient and vast Universe we often wonder where all the aliens are, but just as concerning is where all their ancient and vast artifacts are? So, today we are returning to the topic of the Fermi Paradox, the big question of where the aliens are when we live in a Universe that is so enormous and old. It seems hard to believe it shouldn’t have spawned billions of civilizations by now. Now, what we really mean is, why aren’t we hearing communications from them, and why aren’t we seeing the signs of vast and ancient empires. Where are these empires, and if they no longer exist,
where are the ruins of them? Where are their pyramids or Stonehenge, so to speak? To be fair, many folks think the pyramids or Stonehenge are examples of alien work themselves, but in this context, we’re talking about megastructures, the sorts of things that dwarf even the Great Pyramid, and which can include examples that would dwarf even a planet. Things we could astronomically see, either by their sheer enormity or by their sheer quantity. So, I thought that today we would examine these apparently absent megastructures from a few perspectives. If they are actually missing or if we are seeing them but just not recognizing them as artificial. If they are abundant but not where we expect, like if civilizations build in interstellar voids rather than around stars, or even in pocket dimensions. If they simply do not build such megastructures, either because they just never get the resources and numbers for it, or they lack the desire to. Or if there’s just no one there to build them.
Those and other options are what we’ll be considering today, and as is often the case with our Fermi Paradox episodes, it will probably run on the longer side, so make sure to grab a drink and snack and don’t forget to hit that like button and to subscribe to our channel if you haven’t already. Now, if you’ve seen our episode: the Megastructure Compendium, you’ve a pretty good idea what sort of constructs we’re talking about when I suggest they would be astronomically visible by sheer size or quantity. Our basic concept for today is that we’re not seeing them and that we should be, and that indeed the quantity of them throughout the Universe should be growing, such that as we look back in time by looking at more distant parts of the Universe, we should be seeing fewer of them in a given area, the Time Elapse Argument or TEA, which we’ll come back to. Astronomy is history though, as we like to say, and when we look far away we also look far back in time, and we need to remember that when listening for intergalactic messages, because they’d have been written long ago. To summarize the core concept for today though,
it is assumed that the longer a civilization exists, the bigger it is going to grow until it has comfortably maxed out local resources – we’ll also return to that point later – and the more things it is going to have built. In this context, we mean that term ‘civilization’ very loosely, to the point that civilization is less a continuous nation or empire, and more of a species, or even a clade in both the genetic and creative sense. I wish there was a different term available besides civilization or species, but essentially we mean a continuity of intelligent life and information. If three thousand years from now, Earth has been blown to smithereens and classic humanity has ceased to exist in favor of various genetically altered humans, cyborgs, and AI, that would certainly seem to imply that both our civilization and our species have ceased to exist. However, from the Fermi Paradox standpoint, it is the same civilization, just as the fall of Rome, or the Pharaohs or whoever, didn’t end human civilization.
Now, I scheduled this episode to be written sometime back in April, but, much like in astronomy, my episodes have a time lag. So as I got around to drafting it a month later than planned, I had coincidentally watched both the Sci-fi Disaster Film Moonfall and Doctor Strange: Multiverse of Madness, and then binged on Marvel Comics lore videos by Nerdsync and Comics Explained, and got rather absorbed by one where Rob was discussing the origins of Galactus, Eater of Worlds, as having come from a prior iteration of the Universe. Spoilers to follow, by the way! So, while the originally planned focus was to look at our concept in more of an update of the Dyson Dilemma, and in the context of known science, I also want to contemplate the Fermi Paradox and the absent megastructures, in the context of some of the sci-fi concepts. Now, Moonfall shows us a hollow moon built by ancient human precursors who came up on the losing side of an AI rebellion, and there are all sorts of problems with this, but it is a Rolland Emmerich disaster film, so we’re not going to judge it for scientific realism anymore than we would an MCU or DC flick. But I wanted to raise this from the outset because a lot of times on this show we say X, Y, or Z may be a common technology or plot device or strategy in sci-fi, but it doesn’t work under known science and relies on things in contradiction to our current understanding. We will be trying to zoom
in on what our options to explain the apparent absence of megastructures under known science are, but since we are all going to contemplate a lot of those sci-fi scenarios anyway, because I and most of this audience are scifi geeks, I figured I should add some of them to our list to discuss. So, why isn’t the Universe littered with the relics and constructs of a trillion current or extinct civilizations? A point I often make about Faster Than Light Travel and Time Travel is that, while they’re not allowed under known physics, they only exacerbate the Fermi Paradox if you find out how to do them. And so do Multiverses or prior iterations of this Universe, if travel between them is possible. If it's weird that no one in our galaxy is currently transmitting hello signals and has never been willing or able to colonize the galaxy, it’s even weirder if there’s FTL, not only making that easier, but allowing intergalactic empires. Same for time travel, you’re not just dealing with if we might be one of the earliest intelligent species to arise, but also all the future civilizations that might arise and invent time travel and decide to visit our period or earlier, or even to colonize or conquer them, like Kang the Conqueror, who I’m guessing is the next big MCU villain. Well, if we’re contemplating prior iterations of our universe or people jumping over from other Universes, you really start having problems justifying how this could be possible and explaining why we’ve never been visited.
Now, we have to put a caveat on that in terms of megastructures and ever expanding civilizations because once you throw in alternate universes and so on, you start having to consider if civilizations migrate out of their birth universe to areas where life would be less likely to arise on its own, but where the setup and rules of physics are more beneficial to high tech civilizations. Some Universe where the speed of light is faster, or where entropy is less brutal, or where gravity is too weak for planets to form but allows for the building of insanely huge structures that won’t collapse in on themselves, or one where the physical constant allows for superstrong materials. Indeed, they might have places they mine for resources or energy that are awful for life to emerge in or dwell in, and so they migrate to the optimal place for them to exist, then pull resources from those other vastly more abundant sources.
You could have megastructures in parallel or higher Universes that had broom closets bigger than our whole galaxy or which even stretched into multiple universes and dimensions themselves. Imagine a computer mind that spanned not just one star, like a Matrioshka Brain, or even a whole galaxy, but spread itself through several realities. And a lot of your eternal growth problems don’t actually apply in certain multiverse setups… see our episode on Parallel Universes & Alternate Realities, as well as our episode: Infinite Improbability Issues, for more details. Now, what is this eternal growth problem? Well, it’s the basic Malthusian notion that if you’ve got finite resources and something capable of exponential growth, it’s eventually going to grow to hit that cap. This, honestly, is a really simplistic notion from the late 18th century that just wasn’t able to really look at everything involved, but it spooked a lot of folks into thinking humanity and its growing numbers would one day hit some maximum population, ignoring that it had routinely done that for many centuries before, and then we would descend into some chaos and the fall of civilization. This is called a Malthusian Catastrophe and people often
feared it was right around the corner, especially when I was a kid in the 1980s, and everyone seemed to think we were in a race between the Population Bomb and Nuclear Bomb, with either of them ending in what’s left of us running around as mutant cannibals in the wastelands of a barren planet. I seemed to be in a minority for thinking we’d survive the year 2000, but I’m a noted optimist. As a result, it often makes discussing future mega-civilizations numbering in the quadrillions or quintillions kind of difficult at times because a lot of folks really do have a visceral reaction to the simple concept of us growing to such numbers, rather than the more core idea that we should not despoil all in our wake while growing recklessly quickly and brutally cannibalizing each other. They’re not separating the two concepts. The reality is that we don’t have decent predictive models of how our own population on Earth is growing. I know
folks often think we do, that it’s going to grow to X by year Y or stop growing at Population Z or contract to some Hypothetical lower value. We don’t know because Earth is composed of hundreds of different cultures, each with different views on ideal family values and sizes, that shift with time and only loosely describe an individual's choices. This is why population estimates tend to be less accurate than weather forecasts. Technology shifts, laws shift, incentives shift,
and that’s just with the modern humans of the here and now. It doesn’t speak to aliens, let alone multiversal critters. So, I personally take the stance that in the long term, while resources are available, folks will tend to seek to utilize them or to obtain and store them, as biology seems to encourage, as also does logic. One of the more common things to do with those resources would seem to be to build either huge numbers of megastructures or fewer, larger megastructures, whether that’s for giant space habitats or giant space guns or giant space portals or giant space computers or giant space vaults for storing resources for later, for your giant space empire. Our idea is essentially that, over very long timelines, species or factions which prefer to grow – either in population or resources – will come to outnumber or out-influence those who don’t, as long as the situation permits that; and it doesn’t just mean when they run out of resources. As things get more developed, folks might notice that crowding wasn’t here yet, pies weren’t getting cut into smaller and smaller pieces yet, but that this seemed on the approaching horizon and the balance might shift. Same a civilization in contraction
either gets replaced or sees this is happening and some of its elements press for growth. I usually summarize this as saying that civilizations will tend to grow when they can comfortably do so, and with the caveat that some might not, but when we’re talking about civilizations growing over a whole galaxy, the rare one that doesn’t, simply disappears. Alternatively, if galactic growth is something that only a rare minority actually did, one in a hundred civilizations or so, then they would sprawl all over the galaxy and its billions of systems, while those others, once relatively numerous, were tiny dots on the galactic stage, on their hundred or so homeworlds. I occasionally like to point out that
math doesn’t dictate reality. Apparently cyclic behavior in people or civilizations is driven by actual cause and effect, not the equation that seems decent at predicting it. Things prone to exponential growth - in practice - do not tend to do this because they are following an equation. The equation is our simple, first order estimate of how something behaves. In practice, a species which is exponentially growing – like the original lifeform, presumably – eventually approaches local maximums and you start seeing divergence too, and some adapt to better live off unused resources in the environment and some adapt to live off them, cannibals turned predator-prey cousins.
And that’s still way over-simplified, I just pick it because it sounds sinister. In practice, you get an ecosystem of competing interests, symbiotic relationships, parasitic ones, and more, and even more when we include brains in the mix. If one group gets too powerful, others might rally against them, if a coalition makes enough progress towards its goal, its own internal factions might feel more free to fight factional disputes, weakening them as a group or causing a divide. This is common in two-party power structures composed of many smaller factions. I don’t view these as inevitable or cyclical things incidentally, I just view them as dampening forces on exponential growth. But they don’t really apply to why folks would
choose not to expand out to the stars or seek to take all the random and dangerous rocks floating around their solar system and put them to use before they hit their planet, hit their sun and become hard to get at, or just get perturbed and launched into interstellar space. There’s no implied unity here, anymore than now, or in various expansion periods on Earth. There might be unity, it might be helpful, but it isn’t needed, and indeed competition is often beneficial too. Now, I do tend to think civilizations tilt toward the rational and peaceful more as they get more technological. I don’t take that as a given, just that technology tends to require an appreciation
of logic and patience and being restrained in conflict when there’s so much wealth and resources that qualify as fragile rather than easily seized. I don’t think this represents an inclination of all advanced civilizations to run on hugs and good will, just to be a bit more predisposed to reasoned responses. Note that reasoned isn’t always kind or nice either. Let me add the caveat here that I mean actual reason and logic, not sci-fi or Hollywood logic, like your typical cliché AI or Vulcan. Humans being irrational is a truism, we are the most
rational life form on this planet. Most of the stuff we call irrational is actually really rational, just not updated. Nature encourages us to be cautious and mostly hostile towards anyone that’s different to us or acting atypically, that *is* rational behavior, and is the reason why we’re programmed to act that way. There are very good and logical reasons, not just ethical ones, why a more considered approach is beneficial to humanity. But that doesn’t make those old kneejerk reactions irrational, just often sub-optimal. But, it’s a sad reality that, while science fiction often bemoans that aliens might judge us for our bigoted ways, realistically, they are likely to shrug with indifference to that realization because its something they’ve had to tackle too. And we probably
don’t want to assume they came out the same place we are now or will be in a century. The good news though, is that if aliens are around that are more advanced than us, then they have thus far opted *not* to wipe us out, which to me would imply that all our high-minded ideals about individual values and dignity and respect are not just stuff we made up one day. That they feel we as individuals and our cultures have some sort of merit. This, incidentally, is one of the better reasons why megastructures might be absent. They actually aren’t, we just happen to be crammed inside one. You may think of this as Earth with an artificial fake sky crystal sphere around it, or the whole solar system, or even the whole galaxy. Or an artificial pocket Universe they made for us as a zoo, nature preserve or quarantine zone.
Indeed, we might live in a virtual universe they made for us after they killed us all and scanned our dying brains into digital uploads and a simulated Universe. Or, you might have done this to yourself, incidentally. It’s very normal for us to wonder if this is all a dream or if we’re recalling past lives or so on, and while that can obviously lead to some unhealthy solipsism, that doesn’t necessarily make it untrue. I am not some voice
in your head right now, trying to clue you in to your reality being fake, but you’ve no reason to believe that based on the universe around you. Nothing here, nothing anyone else can say, can ever meaningfully prove or disprove if this is all real or if any of this matters. Which is another possible reason we don’t see these megastructures. They might not get built because hyper-intelligent creatures believe there is no purpose in this Universe, and they opt to gamble on another one. You might be some million year old superhuman, or superalien, with a relative IQ of 200,000, but still be stuck on the feeling that entropy is going to get you eventually in this Universe and that there’s nothing new for you, just endless perturbations.
Like reading the same basic plot of a book, all the characters have different names and places but it’s version two million of the young naive farm boy who finds a magic sword and turns out to be a prince. It’s not a bad story but it’s just kind of blah after a few hundred thousand reads. You might just opt to shutdown or commit suicide, but it’s also possible that your civilization has options for leaps of faith. Heck it might even lie and make some just to give folks an apparent choice. Maybe you’ve invented a way to travel to new universes – you think – but it is believed to be a one-way trip. And the math all works but nobody has ever found a way to return
and say “yep, portal works, new young universe on the other side” so, eventually, everyone has to make that leap. Or you think this universe might be real, but you just can’t be sure and it’s lost its flavor, so you are gambling that, if it is a simulation, your death is going to either awaken you into a new world or reincarnate you into another sim or just simply not work, that something will keep you from actually doing it. Coincidence and distractions. We have the option for patience on this, the Reaper is going to swing by eventually. And in theory, so do they, but while any finite number is miniscule compared to infinity and immortality, there’s probably a big difference between us and some biological immortal posthuman – or postalien – contemplating millions, billions, or even quintillions of years as it waits on the Heat Death of the Universe. Now, I don’t buy that one as being a civilization wrecker personally. I think a civilization headed that way would see many of its members, if
necessary, just flat out indoctrinate themselves into a belief that life had a purpose and that reality was, well, real. You see folks around you jumping off metaphorical, or literal ciffs, so you brainwash yourself to never doubt free will and reality then erase your memory of doing it. You can make a good case that we already did that, this isn’t exactly a new discussion just because we’re adding aliens and advanced megastructures into the mix. To me, it would instead be a reason why I would expect those huge artifacts, because they definitely make for something to do if you’re bored. I mean, if you’re trying to find a grand purpose, something you feel
will take you closer to what’s true and divine, then building a planet is a pretty good choice. Again though, where you build is a bit more of a tricky issue. One that folks often object to, in the context of the Dyson Dilemma, the basic notion that civilization will seek to enclose their sun to maximize their available power, is that they might not choose this option in favor of better options. Indeed, folks commenting on the matter to me are usually pointing out a whole slew
of alternatives that are better than a classic dyson swarm that they know of because we’ve done episodes on them. Like controlled fusion instead of a star, or using starlifting to take your sun apart to use as fuel when you need it, or dumping it down a black hole and so on. And speaking of black holes, we often contemplate using them to fuel civilizations long after the stars burn out, and often via ultra-cold computation, which works better when the Universe is older and colder – the Heat Death of the Universe isn’t about high temperatures – and that makes stars inside galaxies bad places to set up shop in the here and now. So folks migrate their civilization to the
edge of the galaxy or even the edge of time. Which sounds good, but the problem is, you wonder why they’re not migrating a lot more material with them. Maybe that’s what Dark Matter is, all the big posthuman intellects surviving on the galactic halo, as computers around black holes, nigh invisible except for their gravitational pull. We’ll be examining black holes as a dark matter candidate next week and there are some less mundane scenarios for that like this. Civilizations evolve and decide to harvest their corner of the galaxy a bit then head to the Rim with a nice stash of raw materials. We just happened to have arrived on the galactic stage when about 80% of the available matter has been collected and migrated to its purpose.
Except, that would imply that a billion years ago, there would have been less dark matter and more visible matter, and two billion years ago, even less, and three, much less again, and so on. Problem is, we can see galaxies billions of light years away, as they were billions of years ago, and they’re the same as the ones in the here and now, in terms of dark matter content. This is an example of what I call TEA, or the Time Elapse Argument of the Fermi Paradox. Any astronomical phenomena we might scratch our heads at and wonder if it’s natural or a sign of artificial and intelligent creation, needs to be viewed in the context that, as the Universe aged, more worlds should have come into existence which could spawn intelligent life and those that did should have had more time for them to grow and do stuff, like mega engineering and galactic colonization. Thus if I’m seeing a phenomenon a billion light years away in about 1 in 100 galaxies that are at roughly that distance, and thus we see them as they were a billion years ago, if I then look at a bunch of galaxies 2 billion light years away, two billion years ago, and we see that phenomena still in 1 in 100 galaxies, it's not a good fit for us to assume that it must be a product of intelligence. Alternatively, something like
quasars, ancient hyper-active galactic cores, were much more common in the ancient universe and thus, when looking at galaxies many billions of light years away, we see tons of them, we’ve found over a million of them thus far and they seem to have peaked about 10 billion years ago. Which is to say, they are at their highest density 10 billion light years away. Whereas, there are very few near us, with Markarian 231 being the closest known, at 600 million light years away. They are probably nearly extinct in the Universe by now. Of course reigniting them artificially might be something advanced civilizations do, a tempting topic for an episode, Colonizing Quasars, but if so, no one seems to have thus far. Now, we could take that peak at 10 billion years ago, when the Universe was about 4 billion years old, and say that that is when life first hit its big stride, that there were some planets maybe as soon as a billion years after the Big bang and that some had evolved intelligence on them after just 2 or 3 billion years, not the 4 billion with some spare change that it took here on Earth, the largest part of which was waiting on photosynthesis or cells with nuclei to evolve. Maybe vast empires arose then and peaked out, those quasars being their giant engines to open the way to new universes. Later civilizations were sent signals to just come there and use theirs, or
given a better and simpler design invented later. Or maybe those were the gateways used by folks migrating from an older Universe that spawned this one. We do have theories about the possibility that every black hole that forms, causes a new Universe to appear on its other side. Those quasars could be big white holes and those folks on the other end waited till the Universe was older and calmer to migrate, where stars had lived and died and created heavier elements and planets, rather than migrating at the moment of the Big Bang or the first million or so years when the whole Universe was as hot as a star and around as dense too. Incidentally, the answer to that is almost certainly “No”, but when I was a kid, we had no idea what Quasars were, and them as White Holes was a pretty popular notion. We know a
lot more about them now, and they are indeed very related to black holes, even double black holes, but not as white holes, which is another concept that sci-fi loved but which science has mostly moved away from. It is a reminder that a lot of our assumptions are guided by what we know now and what we kinda-sorta-half-guess and infer from theory, so, that could all change in as little as a single generation. Way back 20 years ago when I was a grad student studying physics, dark energy was still pretty debated as a core concept and dark matter was even darker and the notion that the Universe had an expanding acceleration was just getting to the point where it was starting to be taken seriously and was becoming the new consensus.
In that context, I don’t want to casually chop options out of reasoning based on known science, but we also can’t ignore where it seems to have breaks with that. If we are wrong about our predictions and guesses for thousands of years from now, it just gives future generations standing on our shoulders a chance to have something to do correcting our errors. This isn’t all physics and astronomy either. We also base a lot of our growth notions on
the idea that it is biologically hard-wired into anything which clawed its way up Darwin’s Ladder, but a couple notes on that. First, it's overly simplistic to act like having a desire to survive, survival of self or species, or procreation. That these are actually hard-wired into us or anything else. We have a habit of acting like those are carved in as single-sentence directives or rules we follow. They’re not carved into any stone tablets, they’re collective evolutionary kludge
and patches. Thousands of unrelated traits that evolved in us, and not all of which we share with all of our cousins, which collectively favored mechanisms that made us more likely to not die or want to die and to reproduce, especially favoring traits that made us more likely to successfully reproduce before dying. We routinely ignore those built-in tendencies, and since many are no longer terribly reasonable inside our technological civilization, we might curb or remove them or just modify them to the updated environment rather than patiently waiting millions of years for evolution to do it. This is what I mean about our old instincts being rational but often sub-optimal. I do tend to roll my eyes when sci-fi stories present us some ancient ultra-advanced civilization that has evolved beyond ambition or desire and has no comprehension of war – and thus, in many stories, cheerfully encourage humanity to do their dirty work for them – but at the same time we shouldn’t assume aliens or post-biologicals or any civilization whose biology is just really adapted to an era where they had technology and ecological dominance, is one where they have the same goals and desires and to the same degree as we do. Nonetheless, that all has to do with ingrown or innate tendencies, biological or cultural, causing you to act in a way which may or may not be logical, based on the true situation at hand. We wouldn’t really expect them to cease to be capable of logic, and logic would seem to dictate that all that mass and energy sitting around, either serves no intrinsic purpose at all, and thus you can do as you pleased with it, or that it’s sitting around waiting to be used in some fashion. Either way, you should either have things you would like to do with it or be trying
to determine what you should do with it. We live in an entropic Universe and one that actively burns itself up too. All those uncolonized dead worlds, asteroids and comets, are not eternally waiting on us all unchanged. They’re degrading, decaying, colliding,
crashing into stars, getting hurled off into intergalactic space, and all around stars who each burn millions of tons of fuel every second. All to produce light, and neutrinos, and those photons of light rarely land on a planet and most will leave the galaxy without even brushing a mote of hydrogen gas. Not even 1 in a billion photons that the Sun produces ever lands on Earth. Wasted, expended, like someone torching a forest, just to keep their toes warm. So, inevitably, they will want to use those photons, all of them, and that’s where the Dyson Sphere comes in, vast constructs or swarms of constructs surrounding a star, to use its power, and eventually, the power of every star they settle too, to the galactic rim and beyond. They will take all of them, because a forest fire is not a thing you seek to preserve. To advanced civilizations, stars are things you put in the basement of your civilization or disassemble for future use. Thus, the Dyson Dilemma, which asks us why,
in a Universe so ancient and huge, with so many hypothetical ancient civilizations, we can even see any stars in the night sky to wonder about the Universe. Why isn’t every single one of them a big infrared blob, invisible to our eyes? Why do we see any stars in the night sky at all? The default interpretation of that is that no alien civilizations exist and thus there’s no one building them. That meshes up pretty well with our apparent lack of visitations. There’s decent circumstantial evidence to think maybe we have been visited, I don’t personally find it compelling, but I don’t think it’s ridiculous to take that perspective. What I do find ridiculous is the notion that our planet is too boring and insignificant for aliens to visit. The less
common life is, the more interesting any example of it would be to prospective investigators, and the more common life is, the more people who might find it worth investigating. There are folks who visit the most out-of-the-way or boring towns, and there are researchers who are interested in stuff that most of us find boring or even disgusting, like studying ant colonies, and I would only expect more of that in an advanced technological society. Therefore, I don’t accept any Fermi Paradox solution that is specifically predicated on us being too boring to visit. Such being the case, I tend to feel that the best Fermi Paradox solution is just that all these absent megastructures and visitors represent not a lack of desire to build them or to visit us, but simply a lack of existence. No aliens near us, and this means within a billion or so light
years. A Kardashev-3 Civilization, one which has captured all of its stars and tapped them, in a galaxy should be visible to us. By its captured light, emitted as waste heat, as far back in time as they existed in any place the light could yet have reached us. We’ll skip the calculations,
especially as they have big margins of doubt, but since there are a million times as many galaxies a billion light years away as there are 10 million light years away, we would usually assume that, even though a civilization that arose 9 million years ago, 10 million light years away, would still be invisible to us, then there should be a ton more a billion light years away that evolved to technology, say, 1 billion and 1 million years ago. The number of galaxies contained inside a volume generally rises with the cube of distance. So, while life should be rarer the further back in time you look, or the further away you look, it wouldn’t seem likely that it was that much rarer or that we just happen to coincidentally have all the other intelligent civilizations just outside our light cone – the combination of time and distance which we can see. Of course, many would say we can’t see them because they’re eclipsing their stars with their megastructures, but they’re not. They’re absorbing their light. Well that light from a star is itself the product of gamma radiation made in the core from fusion that gas in outer layers absorbs, heats up, and emits in different wavelengths, mostly visible light for our sun. The hotter
something gets, the faster it emits energy as photons, of whichever wavelength, and it goes with the fourth power of temperature. Twice as hot, 2^4 or 16 times faster. 10 times as hot, 10^4 or 10,000 times faster. The color mix on sunlight from stars is based on how much energy they produce by fusion and how much surface area they have available to get rid of it, as they’ll keep heating up until they reach an equilibrium. The same thing applies to a Dyson Swarm,
but they are assumed to be about room temperature not solar temperature, thus, would peak at certain wavelengths of the infrared spectrum. Some years back, just about when I did our original Dyson Dilemma episode, we had scanned around 100,000 galaxies looking for any sign that they had more of that wavelength of light than we would expect. And we looked around to see if there were any blank spots glowing in the infrared but not visible. We came up with nothing.
They could be storing that energy but understand that a system not losing heat by radiation should keep raising its temperature, and remember that the Sun makes up 99.86% of the mass of the solar system, meaning most of the solar system is already insanely hot. If enclosed so that it didn’t leak energy, the rest of the solar system, even a Dyson Swarm, would heat up in very short order. Especially as most of the remaining mass is already hot, like Earth’s Mantle and Core, Venus, and all the gas giant cores. Maybe they have some way to store heat?
I can’t say no on this one, it is one of those technologies any civilization would mortgage its soul to get its hands on, so if it is possible they are almost inevitably going to find out how to do it, and it changes the game a lot. But I really don’t expect to see any violations of the Laws of Thermodynamics in this Universe, indeed, I’d give better odds on being able to cheat entropy by migrating to other realities. What’s more, it is another example of how a super-technology or Clarketech, as we call it, exacerbates the problem. I am trying to figure out why the galaxy isn’t littered with massive constructs and mega-civilizations, and that is not helped by someone showing up with a perpetual motion machine. A civilization with effectively infinite energy via perpetual motion machines or by sucking out vacuum energy or phantom energy or whatever, does not need to colonize the galaxy for its resources. But it can do so very easily, so you would expect colonization
to happen just because some folks wanted the elbow room. Remember, we’re not contemplating truly unified civilizations sprawling over a galaxy. This is a statistical process, conducted over the course of millions of years, same as various hunter-gatherer tribes radiating out from Ethiopia or wherever, weren’t sending notes back there to check if their tribe should move again or split up or cross that land bridge. But, it would seem likely that folks do try to stick together in many cases and that raises another problem. Folks suggest that we probably
only use existing stars till we get better power systems and even just controlled fusion might count, but we’ve got options like black hole power generators or maybe dark energy or vacuum energy or what have you. Most of the mass in the galaxy is not in stars, it is floating around the void, so they ask why folks would bother Dysoning up, in favor of just grabbing some fuel and building their civilization where they want. And as we examined in our Deep Space Habitats episode a few weeks back, this works just fine. But a couple problems. First, most of the mass in a solar system is in its star, and that includes heavier elements than hydrogen and helium, so you probably want to star lift those and take them away.
Second, not only does large-scale artificial fusion leave the same sorts of techno signature as a dyson, but odds are that a megawatt of solar panel collectors is easier to maintain than a megawatt of fusion reactor, so leaving stars untapped doesn’t make sense, and we see quintillions of them. Or billions of galaxies containing billions of stars anyway. Which brings up point 3, when we surveyed those 100,000 galaxies, we were not looking at individual stars, we were looking at ambient infrared galaxy-wide, so Kardashev-scale civilizations that are just spread out wide rather than centralized on a star would have been equally visible. Fourth, unless your physics is really different from ours, it takes a lot more effort and time to send messages or people to various megastructures and habitats further from each other, so you will generally begin finding some optimum balance of desired elbow room with compactness to minimize travel times and signal lag. Problem is, a Dyson swarm is already stupidly spread out, because space is huge, and in order to radiate heat, you have to get wider faster than your density rises. A Dyson Sphere built around a star that’s 100 times brighter than our sun, needs to have 100 times the radiating area to avoid being burned to death, so it needs to be 10 times wider, which means it has 1000 times the volume, meaning it is a tenth as dense. If they want to live cooler, to take advantage of ultra-cold computation, they need even more space, again, the rate at which you radiate heat goes with the fourth power of temperature, so, if you are computing at a tenth of Earth's temperature, then you need 10,000 times the radiating surface area.
Now, we can go through any number of what-ifs about how one might hide a megastructure, but none really seem to hold up, considering that, for us to see the galaxy as we do today, every single one of the potential megastructures would have had to have been hidden, and for every civilization that’s ever existed to have always done so too, not just some species of paranoid builders. Fundamentally, what it all comes down to is that such megastructures are incredibly attractive to build, and presumably, nobody building them has any reason to hide them from primitives anyway. It would be easier to just hide the primitives from you instead, by sticking them in some megastructure zoo or preserve. So, in the end, the best reason to explain
the apparent absence of megastructures is either, no one has built them yet because no one exists to do so, or, they already did, and we just happen to be crammed inside one. Incidentally, if you want to hear more on megastructures and the Fermi Paradox I just finished up an interview with my friend Rod Pyle on Alien Megastructures that will be coming out tomorrow, Friday July 22nd, 2022. Rod hosts This Week in Space and if you want to catch the show now, his guest from last week was Astronomer Tony Cook from the Griffith Observatory who was on Rod’s podcast discussing those amazing first images from the James Webb Space Telescope.
It took a lot to get Webb going but now that it's running it's helping unlock Secrets of the Universe. Those were just awe-inspiring images to see and if you’d like to learn more about the history of the James Webb Telescope, and what it does and how it was built, there’s an episode of Secrets of the Universe on the James Webb Telescope over on Curiositystream, as well as another on the Building of the James Webb Telescope. Speaking of podcasts though, we do an audio only version of this show every week, with and without music, and we also do an ad and sponsor free version of the videos that we put up on Nebula, our streaming service, and now we are going to add our podcast up there ad and sponsor free on Nebula too, and like all our episodes they will come out on Nebula a few days early. We also often have extended editions of our episodes on Nebula and we have one today, as that that conversation with Rod Pyle inspired me to write a bit about the concept of Loud Aliens and their role in Megastructures and possibly even Kardashev 4 civilizations, which I might turn into a full episode on Grabby Aliens in general down the road. Now Nebula is our streaming service where you can catch all those extended editions of our show, some Nebula Exclusives like Planets vs Megastructures and the Coexistence with Alien series, and now our audio-only version of the show ad-free. And all our new episodes, video or audio, come out there a couple days early and without ads or sponsors. It’s also home to an ever-growing number of content creators and
is the largest creator-owned streaming service out there, making it a great way to help support some of your favorite channels while getting ad free content and bonus material. Now you can subscribe to Nebula all by itself but we have also partnered up with CuriosityStream, the home of thousands of great educational videos on amazing topics like the James Webb Telescope. That lets us offer Nebula for free as a bonus if you sign up for CuriosityStream using the link in our episode description. That lets you see the amazing content on Curiositystream and Nebula for less than $15 a year, just use the link in the episode’s description. So we were talking about awesome podcasts and interviews and I wanted to give quick shout out to our long-time friend and fellow creator John Micheal Godier, who has an episode of Event Horizon coming out later today with his interview of David Brin, who coincidentally was our Audiobook of the Month winner for this month for his amazing Uplift Series, and Uplifting was the topic of a collab episode John and I did some years back. John’s a great host and David Brin is an amazing writer, thinker, and speaker, so I’m sure that’s going to be a great episode and I’ll link it in this episode’s description when it comes out, or you can just subscribe to his show, and feel free to practice by subscribing to this show if you haven’t already, it will give you notifications when our new episodes come out. Speaking of those upcoming episodes, next week
we will be exploring Black Holes and Dark Matter, twin mysteries of modern science that might have a lot in common. Then we have our livestream Q&A coming up next Sunday, July 31st, at 4 pm Eastern Time, where you can get your questions from the Chat answered on any of our show topics. Then we’re into August to examine the notion of survivors fleeing disasters or attacks to new worlds, like Earth, in Alien Refugees. The week after that we will look at the possibility the reason we don’t see any aliens is that they all blow themselves up with Technological Time Bombs, leaving no surviors. Then it will be time for our Scifi Sunday episode, Dumbest Alien Invasions, where we’ll examine the weirdest attempts and motives in fiction to invade Earth. If you want alerts when those and other episodes come out, don’t forget to subscribe to the channel and hit the notifications bell. And if you enjoyed today’s episode, and would like
help support future episodes, please visit our website, Isaac Arthur.net, for ways to donate, or become a show patron over at Patreon. Those and other options, like our awesome social media forums for discussing futuristic concepts, can be found in the links in the description. Until next time, thanks for watching, and have a great week!