Extragalactic Sanctuaries: Escaping to the Edge of Space and Time
This episode is brought to you by Brilliant As we journey outward to the stars to claim new worlds, many might make the trip fleeing pursuit, and against a determined enough hunter, even the vast voids of interstellar space may not provide you sanctuary. So, one day you or your civilization decide your safety is imperiled and you wish to ensure that safety by going to the most remote place you can find, and today we will be discussing why you might make this move and how you could go about it. Our main focus will be living outside of galaxies, not between them, but we will be contemplating everything from hiding inside more remote parts of interstellar space, up to migrating to a cosmic void today. This episode is a quasi-sequel to last week’s episode on Deep Space Habitats and a quasi-prequel to next month’s episode, Alien Refugees, and while you don’t need to have seen Deep Space Habitats to understand this episode, you might want to watch that episode first, as its the basis for how you could find the energy and resources to dwell in what is essentially a barren nothingness.
Now, to understand our concept, we need to set the stage by repeating the point from last week that interstellar space is a vast sea of near nothing, even compared to the emptiness of interplanetary space. Earth is one tiny pale blue dot in the immensity of interplanetary space, occupying less than a trillionth of what we might consider the Habitable Zone of our Solar System, which itself is perhaps a millionth of what we might think of as the interplanetary space in our Solar System, out to Neptune, Pluto and the Kuiper Belt. And yet this is a tiny fraction of the volume of interstellar space itself, even in its vast emptiness, it is but billionths of the volume of our Oort Cloud and the vast gaps between even our nearest neighboring stars, which, in turn, are even more empty than interplanetary space. As we saw last week, we don’t need that much improvement in our technology in order to be able to live and live well even in the dark depths of interstellar space, and in theory it should be a place that attracts few competitors and in which hiding is easier. Amusingly though, it’s also where you’d put your best detection gear since noise is minimal. There are also lots of actual stars in intergalactic space too, it’s just much thinner than inside the galactic disk; enough to build relay chains to other galaxies. So in that regard there’s
likely to be lots of old science stations and even settled star systems in intergalactic space. But stealth in space is no easy thing, for my part I don’t think it’s truly possible to hide from an enemy who wants you dead badly enough, even in the dark void between stars. Nonetheless, it would require a very determined foe and not one that is acting out of fear. If we control interplanetary space and a whole star, some tiny refuge of a few thousand folks buried into an icy cometary body a lightyear from my star means so much less than nothing to me as a threat. They’re not out producing us, and we are getting way more research and development done every day then they’d get done in a millennia. Realistically, it’s not some tiny pacific island
with a small tribe living on it versus a major nation, it’s the entire human civilization and infrastructure versus one lone flea sitting on a plastic bottle floating in the ocean. They just are not a plausible threat, so if you’re hunting them, it’s because they either specifically have someone or something you want or they’re just obsessed with killing you. As to what might be someone they want, that might be a pirate crew or leader, or maybe a dangerous political rival living in exile – and such a civilization might have people living thousands or millions of years. That’s a long time to build a reputation or a grudge. As to precious things, maybe a priceless relic, but I think we would have to be talking something like the Shroud of Turin or the Black Stone of Mecca, the preserved body of some leader or prophet, or hunting for Arthur’s Excalibur or the Holy Grail, if they had confirmed magic powers. So too, some hacker who had gotten the codes and one-time pads for an interstellar empire’s dirty secrets archive or Fort Knox equivalents of wealth, or dangerous stowed-away technology might invite such a hunt, but we also have to keep in mind that trying to find some old hermit guarding the Holy Grail in a tiny stealthy rock need not even be in the same solar system. The galaxy is huge after all and it’s hard to imagine what might compel hunters to seek something out through billions of star systems, let alone their vastly larger empty interstellar regions. Plus
often the best place to hide something is going to be a safety deposit box in the capital city, stealth and hiding come in many forms. Fundamentally, Interstellar space is so empty and enormous that if someone is hiding a small sanctuary, you have to be very motivated to go find them, especially something more covert like a post-biological one run on ultracold computers. Indeed, there are even emptier places inside our galactic disk where the spacing of stars is much lower and the galactic halo even more sparse. So going extra-galactic would seem unnecessary. Nonetheless, you might do this for ultra-ultra-cold computing, as extragalactic space is even colder though not by an immense amount, there’s still the cosmic microwave background radiation to contend with.
As time passes, that cooling makes computing more efficient, as we looked at in our civilizations at the end of time series, people might save their fuel for the Dark Age 100 Trillion years from now where they’ll get more efficiency from it. We’re not contemplating Faster Than Light Travel or Time Travel today, though odds are if you’ve got one you’ve got the other, and hiding at the Edge of the Universe in a Temporal Sense, at the End of Time or back at the Big Bang is certainly an option. The Period of 380,000 years after the Big Bang until the Surface of Last Scattering, when Cosmic Microwave Background Radiation was originally emitted, is an even place to hide than inside a Star, another concept we’ve contemplated as an option for a sanctuary before. Still, to return to why you need to hide, I can see some astronomical bounties being offered if someone stole the Shroud or the Black Rock, and interstellar empires might consider offering someone an entire planet of their own to be a modest bounty compared to their economy. Of course, someone choosing to hide need not necessarily be making a realistic estimate of how much people want them. It might be that they were an infamous pirate with a big price on their head
but nothing that motivated any real searches, nonetheless, they think they need to flee to the edge of reality itself to have any chance. So too, while we might imagine a genocidal race hunting down survivors, or alternatively a war crimes tribunal hunting down the fleeing leaders of a genocidal regime, it's even easier to imagine that the folks being hunted are paranoid and perhaps even grow more so as time rolls by. So, why extragalactic sanctuaries beyond just extreme paranoia? Well, they do offer the advantage of being even more remote, while at the same time, the basic principles of deep space habitats still apply. Indeed the gas density in the intercluster medium – the region of space between neighboring galaxies as opposed to intergalactic medium in general – isn’t that much lower than in more barren parts of a galaxy, for those opting to use a power supply that consists of sucking in ionized matter to run fusion, or black hole power generation. We also hypothesized using dark energy or vacuum energy to power your deep space habitats last week and that would be just as effective outside of galaxies. Indeed, anything running on dark energy or vacuum energy would work just as well anywhere in the known universe, even cosmic voids, but those are only about an order of magnitude less dense in terms of matter than the mean cosmic density anyway. With sufficient technology,
and potentially even just controlled fusion, any of these places can be home. Now, a couple months back, in our episode: Lost Space Colonies, I pointed out that a great place to hide would be on the rimward side of one of the stars at the edge of our galaxy or in intergalactic space. You put a statite there to keep your facility pinned behind that star relative to the galaxy, rather than orbiting it, and it’s going to be very hard to find you there, hiding on the dark side of the Sun, so to speak. You’re hanging as close to a star as you can – and that might even be effectively in its upper reaches – so folks only see you if they just happen to be leaving the galaxy and decide to turn their telescope backwards to stare at the backside of that star and watch close enough to see the tiny fleck of your space habitat there. Which they might do. Unlike interstellar space, anything near a star or big object,
represents a tiny fraction of preferred space or valuable real estate, including stars and black holes, and barring travel time, it’s almost easier to search all the interplanetary regions of an entire galaxy than the interstellar space of just a few star systems, but you are now contemplating million-year hunts, not just multi-generational ones. The other problem is that such places are valuable real estate, so, eventually, someone is going to want to colonize it, but the same is fundamentally true of interstellar space if one waits long enough and civilization can colonize it usefully, which is implied by your being able to live there indefinitely too. If you can live there, so can others. Timelines matter a lot, because, as we noted in Deep Space Habitats, a small cylinder habitat is quite capable of powering itself for longer than Earth’s life around the Sun, potentially far longer, just by having an equal mass of fusion fuel as it has station, and that fuel is vastly more abundant than the raw materials for building habitats themselves. Ironically, the kinetic energy the ship, or habitat, or raw materials, needed in order to get out of the galaxy, moving at roughly .2% of light speed, represents fuel needs greater than the habitat or ship would need, to run life support for potentially a million years or more, maybe a lot more. Now, it is important to understand that escaping
the galaxy and escaping our gravitationally bound cluster of galaxies isn’t quite the same thing, and the appeal of the latter is that once you get out into the true deep, the dark energy of the Universe’s expansion is going to aid your escape, and you don’t really need to bother slowing down, once you feel confident you’ve reached the point where your speed plus the Hubble Expansion is going to carry you beyond search, you can just spread some sails out to slowly gather intergalactic gas and dust, very slowly decelerating you while adding to your fuel reserves. This is going to be a long process at every level, billions of years perhaps or even more, but it’s worth remembering that you’re probably talking hundreds of thousands of years of travel to get out of your galaxy and maybe a lot longer if you’re trying to be stealthy about it, not moving faster than other natural objects. Though you might not be aiming for stealth. To illustrate the options, let’s consider a protracted flight scenario. We’ll begin sometime in the 42nd Millenia, in a case where there are no aliens, but where humanity has already colonized and diverged so much that its various offspring and creations might as well be alien. Indeed, even in the Sol System, the trillion minor worlds host millions of different sentient species.
Humanity’s descendants and experiments, and the descendant’s of those experiments. This includes things so alien to humanity of the 21st century that they would not even have appeared in fiction. Some of those, like the giant technorganic ants of the Derzhavin Hollows of Mercury are benign, a quasi-hive mind that placidly trades metal ores for supplies. They have changed little since they were made to help exploit Mercury’s resources in the late 3rd millennia, almost 400 centuries ago. Others, like the vicious Returners from Barnard’s Star,
having been more violent, as they have fought a 400 year war down the spacetower arcology of North Akna Montes, seek to purge all the inhumans from the vast spacescraper, as defined by whether or not they still have the genetically modified wings their ancestors got during the early days of Venus’s colonization, from where their colony ship launched 38,000 years ago. In the 400 years since they seized the spaceport, they’ve managed to fight their way down to claim over 70,000 levels, each level being a vicious battlefront akin to the trench warfare of World War One. This sort of thing has gotten a lot more common in the last couple millenia, old factions that left to colonize the stars coming home to try to reclaim what they see as their birthright.
It’s estimated that humanity, and its descendants, have claimed over a million star systems and sometime around the 30th millenia, those settlers around other stars finally came to outnumber those who dwelt around the vast Dyson Swarm and Deep Space Habitats of humanity’s original solar system, which itself contains over a trillion sovereign nations. It is estimated that at any given moment in Humanity’s birth system, there are 200 million wars going on, and that 3 million people die every single second throughout those war fronts, roughly 100 trillion people a year. For a given definition of the word ‘people’, a term whose definition is often being disputed and frequently is the reason for a given war. Those disputes and others, claim three times as many people every single hour as were alive on the day the first person stepped on the Moon, and more every day than had ever lived in all of Earth’s history before the first person was born off Earth. Those figures don’t include any conflicts out in Sol’s own Oort Cloud or any of the other star systems, nor any of the post-material entities and people living entirely in virtual realities in most cases. It also doesn’t include a lot of sub-sapient machines and creatures. Many will point out that such massive numbers of conflicts and casualties are fundamentally a relative thing, that just because more people die every minute than died during humanity’s wars of the ancient industrial age, doesn’t mean things are more violent.
Quite to the contrary, we are vastly less likely to die of war as an individual now. Nonetheless, many folks point out that the numbers of wars and deaths have risen proportionally in the last few centuries, and talk about the need to bring the solar system back under one common banner. They say that if there’s going to be wars, they should at least be for the good purpose of bringing stability and peace to the Solar System, a War of Unification. And many of you think it might be wise to leave the solar system before such a thing occurs, especially as many of those trumpeting Unification don’t seem to view that as including everyone, and you’re not sure if you would be on that list or want to be. What exactly we are doesn’t really
matter, but we think of ourselves as human, personally anyway. So, we and many others decide to go build a deep space habitat, buying the rights to an old rock in the Outer Oort Cloud that a mercenary group recently purged of pirates. They had to work pretty hard to get the coordinates for that rock in the first place so charged us a fair amount more to ‘lose them’. The trick to stealth in the solar system in the 42nd millenia is the same as it is on any crowded shopping plaza or boulevard of any big city throughout history: everyone sees us, and nobody cares. Now, the thing about a sanctuary, is that it isn’t a very good one unless people know it exists and can flee to it, but since we went and got a nice stealthy base off the radar we would rather keep it as hidden as we can. So, we need a gateway facility and probably
more than one. Then we have to decide if these gateways are public or secret themselves with a long road to reach, so to speak, and if we are aiming for a stealth approach of actually hiding, or hiding in plain sight, we also need to be deciding how we can keep our reputation clean, how we can avoid working with unsavory sorts or them double-crossing us, and how we rule our sanctuary. For instance, can people leave if they want to? If so, are there conditions? Can they communicate to the universe around them freely and if not, how do we police that? Are we willing to violate privacy, willing to scan brains or give people psycho-indoctrination to keep secrets? Are we willing to use lethal force to prevent leaks or runaways? It isn’t entirely lost on us that we could easily end up every bit as ruthlessly authoritarian as some of the factions and leaders who keep talking about the need for peace and security at any price. A lot of this is all hypothetical and we’re mostly out in deep space now, because things seem to be worsening and we are maybe a little paranoid, but we’re preparing for the worst and we want secure and discreet ways to get information, supplies, and those seeking sanctuary. We will take anyone – almost - and so long as they agree to our rules. Out in the broader galaxy, colonization continues but there’s a lot more conflicts in more settled regions than even back in the Sol System. By and large, the galaxy is a pretty chaotic place, though humanity has still only reached out to a small pocket of it a few thousand light years wide. A lot of Sol’s nearer neighbors seem to be more aggressive to each other and internally.
These are the older systems within a hundred lightyears of Earth that have been settled for tens of thousands of years now, and every star near them is long since colonized and developed and home to quadrillions. Many had been shipping raw materials back to the Solar System for millenia and funding colony missions to deeper space and many feel both robbed by Sol, deserted by their own colonies, and crowded by their neighbors. So, it seems like we’ve barely had a chance to get our sanctuary prepared before we start seeing border wars in the Oort Cloud between various minor deep space kingdoms, many just proxy wars between more powerful interplanetary nations in neighboring solar systems. The notion of Unification and Empire seems to be getting more popular too, and by the 44th Millenia, one confederation of factions controls over a fifth of the Solar System’s people and resources and seems to have made a lot of new allies among various colonies in the light century wide inner sphere of great old systems. We decide our deep space habitat, which is increasingly not too secret,
is not distant enough anymore and we decide it will now be a gateway to a new sanctuary far from the Inner Sphere and these Unification Wars. We figure we need to be leaving the local bubble entirely, and we have a very loose coalition of other secret and not so secret allies with similar goals to ourselves, many are the exiles of defeated states in these conflicts. Space is three dimensional so it’s decided that we will set off in different directions but keep in contact, with various secure one-time pads and protocols and a cell-based structure to help if anyone gets captured or turns traitor, or traitor again, many of our allies used to be enemies. This is good because an awful lot of our allies go dark during the bloody few centuries that see the rest of the Solar System placed under one unified rule. That ruler really isn’t anything anyone would call
human either, at least not back when we were born, thousands of years back, but then again, that might be the pot calling the kettle black, in this case the kettle really hates us personally after dozens of centuries of criticizing it, and we’ll just call that ruler ‘Kettle’ henceforth. Kettle seems to have gotten an empire together at this point and is calling for a Great Crusade, out to reclaim all of humanity’s lost worlds. That seems to be Kettle’s priority, but we suspect Kettle would cheerfully send an armada light years out of its way to find us and put our metaphorical head on a spike. So, we personally opt to hide outside the main galactic disc and everyone seeking to join us is routed on a very long path, especially as it takes thousands of years just to get a signal to where we are going, and where no human has yet reached. We opt to build our first quasi-extragalactic sanctuary on the south side of a red giant in the lower depths of Omega Centauri, an ancient Globular Cluster and the largest one in our Galaxy, where roughly 10 million stars are packed into a region only 150 light years across. Omega Centauri is 17,000 light years from Earth and contains more stars than humanity had settled when the chaos back home started.
It’s hard to coordinate a sanctuary over tens of thousands of years, but we can move a lot faster than empires can conquer, and before long, our sanctuary at Omega Centauri has instead turned into one of the largest empires of the galaxy in the 2022nd century. This or that armada or refugee fleet seems to be constantly joining us in our dense cluster, where stars are so tightly packed they are often just light days, not light years apart. The last one to join us fought a 150 century rearguard defensive, chased by the True Empire, as it calls itself these days, from world to world and system to system, burning one after another to ash, while entire colony fleets were sent to do nothing but build fortress systems that could resist and buy time and burn resources in a scorched galaxy warfare approach. One refugee making it in, has the somewhat singular claim of having their parent, grandparent and great grandparent for 100 generations back, each die in a different star system, defending the retreat of their nomadic empire. An awful lot of our unintentional empire is made up of defeated kings, disgraced admirals, and other unsavory folks who were worse than any distant tyrant on ancient Earth.
What qualifies as a person is even vaguer these days, many of the warships joining us, fleeing the True Empire, don’t have any crew, they are the person in question, a sentient ship, and not many folks have classic meat brains these days, at least in Omega Centauri. You can flee so much faster by being a digital signal after all. We know it's just a matter of time before our Sanctuary is attacked, a few thousand years at most, so we plan a retreat. Some plan to flee to other galaxies or less settled parts of our own. Others plan to die fighting or to try to disappear into the massive blackhole at the Center of Omega Centauri, 40,000 solar masses, an ancient remnant of when the cluster was a dwarf galaxy, long before there was any Earth, let alone an empire emerging from Earth gobbling up star systems with greater rapidity than any black hole. Some simply choose to build the fastest and most well-stocked ship they can and hurl themselves into space propelled by enormous Stellasers and Nicoll-Dyson Beams, heading out at nearly light speed and with no hope of ever returning and a great likelihood of finding themselves in galaxies that life will have already developed and conquered in.
Not us, we want to ensure that there will always be a sanctuary, so our technique is somewhat parallel. We aren’t leaving ourselves just yet, not exactly. Our sanctuary will be billions of years from now, and near no galaxy, so nobody has a motive to come there for resources. What we’re doing is hurling out a string of massive artificial worlds, each with a black hole at its center, and containing vast amounts of supplies. Each will act as a relay to the
next ones out, and each will follow a slightly zig-zagging pathway, so that no one can target them with light-speed quick superlasers. The pattern of each zag is random but predetermined, so that they alone know where they’re going to be, except for those relays further out. When Omega Centauri finally falls, we’re the last to leave, one jump ahead of armadas of ships that outnumber a locust swarm and each with weapons capable of leveling worlds. But we take no ship ourselves, first, broadcasting a powerful signal out galaxy-wide, listing a large number of space-time coordinates folks can send a signal to that will be picked up by one of our many disposable relays that the various planet-ship gateways will string out from themselves, so they can’t be targets directly. Then we do what we advised others to, and we transmit our mind digitally to the first gateway, leaving the Milky Way more than a million years after we left Earth the last time. When we awake, it is inside a space station
of epic proportions, as big as a solar system, and surrounded by utter darkness, even to our post-human senses that could see better than most telescopes. Far, far away, we can see the vast darkening globe that once was our galaxy and many others, merged together to form some unknown megastructure we recognize only by its red-shifted light, it appears to be peaking at the source at about double the temperature of the Cosmic Microwave Background radiation, which itself is far cooler than it used to be, and it is red-shifted as appropriate for something that we keep a distance and velocity of 99% of light speed away from, accounting for Hubble Expansion. That’s because this station keeps itself intentionally at just short of the cosmological event horizon from what once was the Milky Way, so that others may transmit themselves down our relay gates to reach us, here at the edge of space and so far forward in time that there are no longer any natural stars, only one vast hyper-efficient computer simulating unimaginably huge virtual worlds to serve as sanctuaries to all. Last to leave but first to arrive as we followed the most straight path, we wait patiently for others to come, knowing no war fleet can ever reach us, and that, at last, we have reached our true sanctuary.
So I was intentionally a bit vague today about who and what are protagonist and antagonist were but the implication is that both are post-human and change a lot over the course of the million-year long timeline and the epilogue a quadrillion years hence. Nonetheless they’re definitely not running on classic brains anymore and yet they probably are still using neural networks, what are own brains use and what was often predicted future supercomputers would use and now, today, more and more of them use ever-better neural networks to do ever more impressive work. But it's still a mystery field to most folks, like a lot of math and science, and yet they don’t need to be. Our friends over at Brilliant have created a number of
interactive courses on Neural Networks that will walk you through the topic of Neural Networks and many other areas of Math, Science, and Computer Science. These topics are often thought to be hard to learn but they don’t have to be, they are much easier to learn with interactive examples, everything is. The best learning is hands-on and interactive learning, hands down, and Brilliant has worked tirelessly over the years to offer more and ever better interactive learning options for math, science, and computer science. These topics often seemed hard in the past because there were so few interactive options compared to other topics, but now Brilliant makes it easier for anyone to learn, be it the basics or advanced materials. With Brilliant, you can learn at your own pace, learn on the go, and learn something new. To get
started for free, visit brilliant.org/IsaacArthur or click on the link in the description, and the first 200 people will get 20% off Brilliant's annual premium subscription. So today’s topic was about escaping to a sanctuary from the perspective of building it for others far from home, and we’ll take a look at it from a different perspective next mont on August 4th with an episode Alien Refugees. As for next week, we’ll return to the Fermi Paradox to ask where all these enormous habitats and megastructures we discuss on the show might be and what their apparent absence indicates about the Universe. After that we’ll look at two of the most mysterious things in our Universe, Black Holes and Dark Matter, and if dark matter might be black holes. Then
we’ll close July out with our Monthly Livestream Q&A on Sunday, July 31st, at 4 pm Eastern Time. 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!