The Fermi Paradox: Absent Megastructures

The Fermi Paradox: Absent Megastructures

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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, 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!

2022-07-24 18:50

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