Preserving Our Species Beyond the Solar System - Part II
In part one we discussed some of the threats facing our species; Earthbound impactors, supervolcanoes, pandemics in a post-antibiotic world, nuclear war, and more. Whether or not we can survive or avoid any one of these threats is debatable. We can expect a genetic bottleneck if not extinction should any of them occur. But the one threat that is unavoidable and will lead to our extinction, is the Sun; unavoidable that is, if we remain on Earth.
Leaving Earth to avoid the next phases of our Sun's evolution is only meaningful if we leave the entire solar system. We looked at other stellar systems within 50 light years of Earth, and considered such important factors as star age, type, and even exoplanet orbital periods and mass. Though life on a tidally-locked planet in tight orbit around a red dwarf could be possible, it wouldn't be easy and certainly have long-term negative physiological and psychological effects that compound through subsequent generations.
We tentatively concluded that finding a younger quasi-solar analog playing host to a quasi-Earth-analog is ideal, and would be our best chance for survival. We didn't delve too deep into why, other than to assume so, given all the benefits evident in our Sun/Earth relationship. After all, we aren't the only species to have found that relationship perfect for survival; several million other species of plants and animals have too. Life may be able to exist on a variety of planets in orbit around a variety of stars, but it may be that for technologically-advanced life to evolve, it would require a star and planet like our own. If it ain't broke...
TECHNOLOGICAL & SOCIAL COMPLICATIONS
Finding the right star is one thing, but finding the right planet around the right star is an entirely different animal altogether. There are limits to our current methods for detecting Earth-mass exoplanets around brighter stars (brighter than red dwarfs), but we're getting better at it. And not to be a blind technological optimist, but I think our tech will improve. Our eyesight into the heavens will improve dramatically once the James Webb space telescope is launched in about a year from now.
But even with the Webb telescope, the task of finding the right combination will remain a daunting task. One option to simply looking around from Earth or Low-Earth Orbit (LEO) is to develop new technology capable of exploring our galactic neighborhood and beaming information of what it finds back to us.
One science-fiction-sounding tech that is arguably doable is to develop self-replicating nanocraft capable of being accelerated to relativistic speeds. We discussed self-replicating Von Neumann probes in the previous blog. There are variations of these probes, but the type most useful to us would be explorer probes.
These probes can build copies of themselves using raw material from any asteroid, moon, or planet (preferably moons and asteroids to avoid the deep gravity wells of planets) then send clones of themselves out to do more of the same; spreading across the galaxy like explorer locusts. Over time, their exponential growth would greatly increase the rate at which new stellar systems are explored and understood, thereby buying us more time to prepare for departure to a place we know well enough to be hospitable. Right now we are only able to infer habitability via spectroscopy.
There is a risk of self-replicating probes becoming too successful. They could theoretically become so numerous over the span of a billions of years that they become a type of berzerker swarm that end up harvesting entire planets and moons at the expense of whatever might be living on them, triggering mass extinction events galaxy-wide. But if they're equipped with artificial intelligence (AI), then maybe they'd know better. Or would they?
Rampant berzerker probes aside... if our self-replicating explorer probes end up finding what we're looking for, then we must face the daunting task of getting there. We briefly discussed the problems of accelerating large masses to relativistic speeds in the previous blog. If we use Newton's 2nd law, F=ma, it would seem all we need to accelerate a mass is simply more force with no upper limit. But Newton's law fails at relativistic speeds. Einstein's famous E=mc^2 equation is really just a truncated version of the full equation. The full equation includes the Lorentz factor; a mathematical term representing the factor by which time, length, and relativistic mass change for an object while it's moving at relativistic speeds.
At non-relativistic speeds the Lorentz factor is equal to 1, hence the reason we can omit it. We can take the most complicated equation in the world, then multiply it by 1 and it won't change a thing. However, when relativistic speeds are reached, the Lorentz factor becomes greater than 1. For example, electrons at the Large Hadron Collider (LHC) are accelerated to 99.9999991% the speed of light. At that speed, the Lorentz factor is 7,454. At 100% the speed of light, the factor goes to infinity.
What that means is, any mass accelerated to the speed of light, will contract such that its length is zero, time will stop for it relative to an outside observer, and its mass would go to infinity. This is why only massless things like photons can accelerate to light speed. Not even electrons can reach that speed (hence the 99.9999991% acceleration to light speed at the LHC). It isn't the fault of the accelerator, but a law of the Universe... the one we're in.
We can see that traveling at relativistic speeds will be hugely problematic from a practical standpoint. As such, we considered using generation ships in the last blog as an alternative. Generation ships as we'll recall, are massive spacecraft capable of hosting generations of plants and animals (the latter including us) for centuries-long journeys through interstellar space.
But such interstellar arks comes with their own problems, not the least of which concerns systems and structural maintenance over such long periods of time. The spread of such common illnesses as diarrhea can bring the entire population to its knees. Just look at the many cruise ships that have to return to port early because of it. Go ahead... Google: "cruise ship diarrhea outbreak"... just don't do an image search. Generation ships will not be able to turn around in the event of any sort of outbreak.
There is also the wild card variable of human psychology. The role it might play within a society subjected to life-long confinement coupled with the constant threat (stress) of system or structural failure looming in the backs of their minds warrants consideration as well. Though studies have been done to evaluate human psychology after long-periods of confinement, most of them involve a known end date and don't have the added stress of looming death on the horizon of an unknown future. They are also closely monitored by those who can get the study subjects to safety. Such wouldn't be the case with generation ships.
Though the following are not for interstellar travel research, year-long confinement on the International Space Station (ISS), or the relative confinement of the HI-SEAS "Mars colony" wouldn't remotely prepare us for the mental rigors of interstellar travel. There will be no communication with the 'outside world', no end date for many generations of people who will live out their entire lives on the spacecraft, no Hawaii outside the window, and a host of other difficult-to-process realities we have no precedent for. Why we ignore our moon as a stepping stone for such research is unknown to me. But I blame my own ignorance for that
Other issues will invariably arise as well... it's obvious that if we want to ultimately reach our destination that may be hundreds of years away, we'll need to procreate en route so that following generations can arrive at our species' new home. Yet procreation will have to be regulated to the replacement rate. Any more and population will grow beyond the resource capacity of the generation ship.
It may sound simple enough, but there will exist the possibility that some couples may need to resort to the use of fertility drugs in order to conceive. We don't know what effects of interstellar travel (and associated HZE ions among other factors) will have on fertility. The aid of fertility drugs may not be a big deal, but they tend to result in the birth of triplets, quadruplets, and even octuplets. No biggy, and even celebrated here on Earth, but on an interstellar ark this would have serious impact on other couples' right to have children.
Imagine the scenario where a couple resorts to the use of fertility drugs, and that use results in the births of several children. Though an exciting and precious thing, it would mean another couple (or two) will not be allowed to have any children to ensure population on the ship is controlled at the replacement rate. There may be volunteers, but then again, those 'volunteers' may need to be chosen at random as a neccessity. It sounds Orwellian, but it may be a reality many futurists optimistically overlook. There is also the risk of life lost before a couple can have children. Or perhaps some anomaly where more males or.more females are born than their counterparts.
Consider also that the gene pool needs to remain diverse enough to avoid long-term inbreeding. I know this all sounds pretty twisted, but it's quite serious yet rarely considered. What's politically correct on Earth, may have detrimental long-term effects on what's necessary for survival on a colony ship.
A child policy wouldn't be the only Orwellian feature people on a generation ship would have to live with. There would have to be others, which I don't intend to discuss as they can very quickly lead this blog down a dark path we won't like. Point is, they'll all play into the psychology of the people living together on that ship. And if the Stanford prison experiment, prison life itself, the failed Biosphere 2 habitat of the early 1990s, and a simple glance at any number of daily news headlines don't foreshadow the difficulties that lie ahead, nothing will. We can't base our forecasts off year-long semi restricted vacations in Hawaii.
We can go on about the myriad of problems interstellar travel will pose—whether it be by some hibernation-pod-equipped spacecraft or a big spacious interstellar ark—but can reasonably conclude that getting to another star system alive and well will be unbelievably difficult, and a task that will have to be shared by numerous generations all with a common goal supported by common personal sacrifice for the greater cause.
Some may say we don't need to go to an entirely different star system. We can simply establish colonies on Mars. If we generously assume permanent colonies are Mars could exist, we have to realize that those colonies will not likely be self-sustaining without 2-year (or more) resupply missions from Earth. Just imagine all the HEPA filters we'll go through trying to keep the perchlorates out of our habitats and our lungs (or drinking water for that matter).
Even if we establish manufacturing of spare parts on Mars (HEPA filters included), we'll still be completely vulnerable to the reliability of the technologies we'd be employing. On Earth we have industries backing up industries. If one manufacturing plant fails, there are others ready to fill in the gap and competitively so.
Consider Biosphere 2 of the early 1990s... the carbon dioxide levels within that habitat fluctuated wildly. Well, on Earth when something like that fails, the solution is to simply open the windows. On Mars if something like that happens... you're dead. Gases, including oxygen, can become toxic... it's all in the dosage (concentrations).
Also consider; if some cataclysmic event annihilates life on Earth while folks are living on Mars.. they'd subsequently be stuck on Mars. Without ground control on Earth to guide them home, or send resupplies, or do anything else for that matter, folks on Mars would be truly stranded. If we think about it... even something we take for granted, like medicines, would never be resupplied. Mars colonists can stock up all they want, but fact remains medications have a shelf life, and once they expire they become useless or worse... some medicines become toxic well beyond their expiry date. Also, think of the psychological impact of knowing everyone you know, everything you knew back on Earth is gone... forever.
We can go on... but Mars is an extremely flimsy basket to be putting our veritable eggs in. None of it matters anyway, Mars won't survive the ultra-luminous subgiant phase of the Sun, and would certainly freeze over once the Sun becomes a degenerate white dwarf. Let's face it, if we want to survive for billions of years, we need to leave this solar system entirely.
And just to adress this quickly, I am aware some have suggested using a Shkadov Thruster to move the Sun along with the solar system to a new neighborhood in our galaxy. A Shkadov Thruster is a Class A stellar engine imagined by physicist, Leonid Shkadov. I'll let my readers follow that link (via 'stellar engine') to read more about the Shkadov Thruster, but point here is that the whole idea of us leaving the solar system is to get away from the Sun... not take it with us. Not to.mention we would have to dismantle Mercury, Venus, Mars, AND EARTH to harvest the material necessary to build a Sckadov thruster. Doh!
LIFE BEYOND EARTH - Tougher than the Oregon Trail
Like mentioned above, if we want to survive for billions of years as a species, we'll need to leave this place. And as we discussed briefly in the previous blog, a billion (or more) years is just the kind of time civilizations theoretically need to become stellar or even galactic civilizations; civilizations capable of harnessing the total energy of their host star or galaxy respectively. A stellar civilization ranks as a Type-II civ on the Kardashev scale. A galactic civ ranks as Type-III. A planetary civilization capable of harnessing the total energy of its home planet, ranks as Type-I. The human civilization doesn't make rank yet, and I hope we never do for what I would hope are obvious environmental reasons.
Contrary to futurists' collective optimism, and Kardashev's generalized conclusion, if we ever were capable of harnessing all the energy that reaches our planet from the Sun (~173,000 Terrawatts continuously), then we'd likely cause the mass extinction of innumerous species around the world. Members of the Plant Kingdom sort-of-kind-of need the Sun's energy to do photosynthesis. The trophic cascade that would result from the widespread deaths of light-robbed plants would be catastrophic to all life on Earth.
Oceans need a lot of that energy, far more than many futurists seem to realize. Half of our oxygen comes from algae living in the world ocean (it's one big ocean with 5 different regional names).
If we harvest energy from the Sun indirectly, perhaps after photosynthesis, then we'll never reach Type-I status, because the law of thermodynamics dictates that some energy is lost to heat with each step it takes down the consumption ladder. There's going to have to be some concessions as to how much energy we'll be able to harness from the Sun if we don't want to kill everything on the planet.
Some may argue that we can ensure their survival by allocating some of the energy we've harnessed to that purpose, but then we have to ask, "what's the point of adding a middle person?" That act alone complicates things and creates more heat waste. It's worse than wanting a sip of water, walking up to a natural stream, then asking someone to drink some of it and wait for them to, um, pass it on to you.
Consider the stellar Type-II civilization. This is the level at which an intelligent species is capable of harnessing the entire energy of its host star. We're most familiar with how this might be accomplished by news articles touting the possibility Tabby's star may have a partially-constructed Dyson sphere built around it as evidenced by the yet-to-be-explained dips in the star's light curve. (It most certainly isn't a Dyson sphere, as I wrote here.)
A Dyson sphere, or perhaps more appropriately named Stapledon sphere, is a hypothetical megastructure built to encompass the Sun in order to collect its entire energy output. The sphere itself can be used to vastly increase living space, and the energy can be used for everything we use it for today and then some. And of course, we mustn't forget, a portion of that energy can be weaponized. If we can build a sphere, we can bet our leaders will ensure it is weapons capable.
But here's the hitch; The amount of material needed to construct a sphere around the Sun would be gargantuan, and though there exists a lot of matter in our solar system, most of it is hydrogen and helium; neither of which is usable as building material. This leaves us with the heavier elements found in rocky bodies such as the inner planets, and material in the asteroid belt.
To build our megasphere, we'd literally need to harvest the entire planet of Mercury, and though some futurists have said otherwise, I can assure you we'd also need to harvest Venus, Earth, and Mars... as well as using up everything in the asteroid belt.
According to transhumanist, Isaac Arthur, the dismantling of Mercury alone would take a generation to complete. Assuming self-replicating machinery and on-planet factories are used. To get material off planet, he suggests using huge mass drivers to launch material to where it's needed. He also suggests running mass drivers in opposing directions to avoid adding angular momentum inside the decreasing mass of the planet being harvested for material. This keeps the planet(oid) from spinning so fast it breaks itself apart.
It would take eons to complete the task of dismantling all 4 rocky planets, but by then humans would be alive and 'well' in the Dyson sphere or among the Dyson Swarm. In a swarm, they will be in no particular hurry as their swarm is scalable... we'll get to this in a bit. But you read that first bit right... all 4 rocky planet need to be used up for material. That means Earth is up on the chopping block. Finances and time aside, if we're going to built a sphere, we're going to have to make the decision that we won't need Earth any longer. I question the common sense of that, as the only reason I can think for moving off planet and needing the material of all the others', would be to make room for a huge population... on the order of trillions. That seems a bit unsustainable to me.
For some enthusiastic technological optimists (aka transhumanists), that may be ok. If the inside surface of a Dyson sphere can be made livable, then we would have enough living space with today's population to give each person a home with a (metal) yard the size of Africa.
We'd have to charter one of Elon Musk's Hyperloops just to visit our next-door neighbor, or make a run to the local grocery store. Not that we could run... see, the sphere would lack gravity. A sphere can't be spun to create artificial gravity via the centrifugal pseudo-force either. At least not everywhere on its surface for obvious reasons. In fact, as we'll get to shortly, we couldn't even spin a habitable band that size to speeds fast enough to generate 1 G of artificial gravity without utterly destroying the band and everyone on it.
Of course life in or on such a sphere (or band) would be without an open atmosphere, without gravity, and without making much sense. It's one thing to have all that space, but geez... trillions of people without a planet? Some folks love the idea, and who am I to say they're wrong for thinking that way.
Constructing a sphere is going to face a lot of problems; not just the issue of creating artificial gravity. But, the good news is there is a more feasible option to building a massive sphere and one mentioned above... A Dyson (or Stapledon) Swarm. It's collectively a positioned horde of low-density statites tasked with collecting the Sun's energy by forming a thick cloud at different positions around the star.
Of course, statites alone won't provide us with a place to live, and we'll need one given that fact Earth will need to be dismantled... sorry all life on Earth, but we have a future to forge! In addition to, or in replacement of statites, we can construct habitats called O'Neill cylinders. These can be constructed en masse. They are megastructures that provide livable space for humans and whatever lucky (or not) plants and animals they bring with them. Artificial gravity can be simulated through the effects of the centrifugal (pseudo) force if they aren't built to big, and we can build more as needed (swarm scalability).
The structural integrity of such megastructures rests solely on the strength of the materials with which their built. And the bigger they're built, the stronger the material will have to be to keep them from flinging apart and killing everything and everyone inside.
Some good news is that construction will be no problem, at least in terms of having to contend with gravity. The negative effects of gravity on massive construction projecys like this are avoided by constructing the cylinders in situ, ...in space.
But as we briefly mentioned with regard to the band idea, we can't build these things as big as we want without consequence. The bigger their radius, the faster they'd have to spin to maintain Earth-like gravity. There is a point at which the rate of spin would exceed the material's ability to hold the structure together, and for this reason there is an upper size limit to what we can build... that is if we intend to spin it to create artificial gravity for those living inside.
According to Wikipedia, O'Neill cylinders can be up to 5 miles in diameter... hmmmm... ok. The equation describing the relationship between the radius of an object and its rotation speed (set equal to acceleration due to gravity at Earth's surface... 9.8 m/s^2) is:
9.8 m/s^2 = v^2/r
I'm terrible at math, but if I did this right, then that means an O'Neill cylinder with a 5-mile radius, would have to spin at a rate of approximately 281 m/s (tangential velocity) to maintain the effect of 1 G. That's 0.33 rotations per minute (angular velocity). I'm not an engineer, so can't comment on whether or not there are known materials that can handle that, but building a 5-mile diameter structure (even in space) and spinning it sounds like a heck of a task.
Anyway, regardless of whether we use spinning O'Neill cylinders, statites, or any number of other options for a Dyson swarm, the fact remains... we'll need to harvest a few planets to build it all. To do so would require we employ the exponential work output of self-replicating Von Neumann probes; a relatively easy task that can be done in 5 steps... apparently. I'm no expert, but would venture to say it would take dozens of very difficult steps to accomplish, but I'm no scientist, nor an engineer.
We'll also need lot of material to create the hordes of self-replicating Von Neumann probes tasked with planet dismantling, and swarm construction. Something not often factored in. To dismantle a planet and build a swarm within a lifetime will take a lot of machinery. Machinery including the probes, as well as construction and manufacturing equipment and infrastructure separate from the swarm material itself. I'd expect there would also be some waste material lost during dismantling, processing, forging, and construction.
I would think while dismantled an entire planet, a lot of material would be lost to space; floating around in orbit as relatively small debris not worth the time or effort of harvesting... especially when more material is waiting to be harvested from the next planet out... ahem, Venus... we're lookin' at you next...
The immensity of constructing a swarm (of any type) around our Sun is truly mind boggling. And we have to wonder if and when we're capable of undertaking such a feat, would that be the most viable way to go? I would venture to say the answer to that question is most certainly a resounding no. At least not with our own star. If anything, we'd want to build our megastructure around another younger star with more stable life left in it. If we're at the point where we can dismantle entire planets to build megastructures on a stellar scale, then we're probably also at the point where we can conduct interstellar travel and do so quite successfully.
And with regard to building a Dyson swarm around another younger star, we have to ask ourselves why harvest its entire energy output when the materials needed to accomplish that feat would require we dismantle many, if not all of its rocky planets? It seems counter-intuitive to show up to a star system only to harvest its terrestrial planets (habitable worlds possibly included) in order to create an artificial environment with nauseating centrifugal "gravity".
I'd begin to question the intelligence of a species that does that. Seriously.
But perhaps type-II and III civilizations don't resort to all that. Perhaps they know of a better way to preserve themselves as a species indefinitely, without the conundrums of evolution, home world harvesting, artificial gravity issues, and the many complications inherent with interstellar travel. It's an odd alternative to say the least, but I'll argue it makes far more sense than trying to do things the way they've been depicted in movies, books, television series, etc...
If an alien species is capable of harnessing the energy of its home star (Type-II), or its entire home galaxy (Type-III), then we have to consider the possibility that they have a very different perspective on everything than we do.
One type of Dyson sphere thought up by Robert Bradbury is a Class B stellar engine he named the Matrioshka Brain (briefly discussed in this blog). A Matrioshka Brain is a hypothetical computer system built around a star such that it can utilize the entire energy output of that star in order to perform calculations. It's a Dyson sphere within a Dyson sphere within a Dyson sphere... each nested within the other like Russian matryoshka dolls, utilizing the decreasing amounts of waste heat from each subsequent inner shell.
The processing power of such a computer system would be vast. Depending on the efficiency of its processors, coupled with the fact the entire system can consume ~384 yottawatts of power according to Dyson, a computer system of this magnitude would have the processing power (not to be confused with power consumption) in excess of 10 quindecillion Hertz; That's a 1 with 49 zeroes after it. Such a system would make the Sunway TaihuLight seem like an abacus by comparison... actually, it'd be more analogous to being a nearly useless rock by comparison.
According to Isaac Arthur, each subsequent computing shell would operate at maximum efficiency if their spacing is calculated precisely using Carnot's Theorem in thermodynamics. The theorem states that the maximum efficiency of a heat engine is equal to 1 minus the temperature of the hot reservoir divided by the temperature of the cold reservoir. In this case, each layer of the Matrioshka Brain is a reservoir, with adjoining layers used in the equation; ie) layer 1 and layer 2, layer 3 and layer 4, etc... the "hot" layer (reservoir) is the one closer to the star with the "cold" layer (reservoir) being the next one out from it.
Arthur approaches the equation by assuming each layer of the brain is half the temperature of the one 'below' it. He explains that layer 1 (closest to the Sun inside of Mercury's orbit) operates at 1000K, layer 2 at 500K, layer 3 at 250K, etc...
By using half-the-temperature steps, each layer works out in the equation to be 50% efficient. 50% efficiency is the theoretical maximum level of efficiency any heat engine can perform according to Carnot's Law... mathematically speaking. Though the reality is that maximum efficiency is likely lower than 50%.
Given this, the distance of each layer from the Sun (or other star) can be determined by temperature. He also goes on to explain that each subsequent layer might be of best use if whatever material it uses to convert electromagnetic radiation for computing purposes is a part of the layer best positioned to absorb a particular wavelength that material performs best with.
Materials capable of working with shorter wavelengths would work best as part of the innermost layer(s), whereas materials better suited to longer wavelengths might be optimal at the outer layers. This idea is based off Wien's displacement law. "It states that the black body radiation curve for different temperatures peaks at a wavelength inversely proportional to the temperature."
In other words, the cooler it gets, the longer the wavelengths become, and vice versa. Materials best suited for longer wavelengths should be placed on layers where cooler temperatures most appropriate to those wavelengths exist, and vice versa.
Obviously things get cooler the further from the Sun, or other star, one gets. This is compounded by the fact each Matrioshka layer will absorb and use some of that energy, converting it to calculations before losing some as waste heat; an unavoidable fact of life (and death) defined by the 2nd law of thermodynamics.
The number of layers needed depends largely on the luminosity of the star, as well as the efficiency of each layer. The outermost layer, however, will only have waste heat equal in temperature to interstellar space; 2.73 Kelvins.
To achieve this, the outermost shell of the brain would be out near the orbit of Pluto (give or take). This means we'd have to move the gas and ice giants in order to make room for our Matrioshka Brain. That's a daunting task given all the orbital energy those planets possess.
One possible way to move them is to employ the use of a Fusion Candle. It's basically a fusion rocket that burns at both ends. This assumes we figure out how to control the fusion process. A Fusion Candle would be huge; somewhere in the vicinity of 15,000 kilometers long! One end of it would dip into the gas (or ice) giant's atmosphere and begin drawing up its hydrogen. This hydrogen would be directed into the fusion reactor at the center of the ship. Part of the energy derived from the fusion process would be used to keep the megastructure aloft by burning downward towards the planet. The rest of the energy would be used to burn away from the planet in the opposite direction.
In theory, over time, this would add orbital energy to the planet and move it out of the way while also decreasing the planet's mass ever so slightly. Of course, this would take a million years or more, but so would the construction of the Matrioshka Brain... soooooooo plan ahead future lowest-bidders.
Anyway, the outer shell of the brain would have waste heat equal in temperature to interstellar space, and here's where things get interesting... as if they weren't already...
At interstellar background temperature, a Matrioshka Brain effectively hides the star around which it is built. For those who read this blog based on Fermi's Paradox, one of the possible reasons why we've not been able other technologically-advanced species beyond our solar system is because they don't want to be detected. One way to do that is to hide their host star.
For a Type-II civilization this equates to just one star. But for a Type-III civilization, this could mean every star in their galaxy. Though building a Matrioshka Brain around every star in a galaxy isn't all that sensible. Many stars are unstable, and the radiation levels near the center of galaxies is off the charts so to speak. I don't think any species capable of achieving Type-III status would want to harness the energy of their entire galaxy. They'd harness what makes sense, and either move on to do more of the same in another galaxy, or stay put and enjoy what they have.
And I'm going purely sci-fi here, but I'll be the first to suggest that one interesting place for an advanced alien species to hide would be among stars in the outermost portion of their (spiral) galaxy, near its theoretical dark matter halo.
Spiral galaxies' rotation curves only make sense if there is extra unseen mass around them. It's the only thing cosmologists have been able to come up with to explain why the rotational velocity of spiral galaxies doesn't decrease at large distances from their centers. But what if it isn't dark matter, but just more stars hidden behind layers of high-processing Matrioshka Brains constructed by a Type-III civilization that wants to remain hidden from prying eyes? Well, I suppose technically they'd be Type-III capable.
That's right, maybe the dark matter halo around spiral galaxies is a ring of Matrioshka Brains, or at least partially so. You heard the idea here first! As far as I'm aware, no one else of thought of this... of course, that's probably because this idea is stupid. It's fun to imagine at least, and seems like it would be a clever idea by the species that constructed their galactic mind halo. But again, it's purely sci-fi and I thought it would be interesting to throw in the mix to churn in our imaginations.
But why would a species capable of such a feat be worried about being discovered? Certainly with their energy capacity they would be armed with weapons powerful enough to annihilate entire solar systems with a single shot. One reason might be related to the possibility that they aren't actually there, at least physically...
A NEW PERSPECTIVE ON REALITY
The universe has been around for about 13.8 billion years. The Sun and Earth have been around for about a third of that time. It's possible that there exists other advanced civilizations that have a billion or more years of technological and physiological (particularly brain capacity) evolution on us. A billion or more years.
It took us almost all of Earth's history to finally evolve. It's theoretically possible that on another planet similar to Earth, with a star similar to the Sun, a species was able to evolve within half the time it took us. This alone buys them billions of years. It could also be that their 'sun' is half a billion years older than our Sun. There's another half billion years. For perspective, anatomically-modern humans evolved only a quarter billion years ago... half of a half of a billion years.
When we run the basic arithmetic, it's not difficult to assume it's possible there are advanced species out there that could possibly have billions of years on us. That's more time than any of us can truly comprehend. Enough time for an advanced civ to build multiple Matrioshka Brains... that is if such a megastructure isn't beneath them intellectually... that is to say, if they haven't thought up something far superior.
The computing power of a system like a Matrioshka Brain would open the door to all sorts of possibilities. One of them being a simulated reality. Assuming computing efficiencies are nearly perfected by the time a species is capable of constructing a working Matrioshka Brain, such a megastructure could be built around a low-mass red dwarf.
At Landauer's limit, even the cooler temperatures of a low-mass red dwarf could supply more than enough energy to run a Matrioshka Brain capable of simulating reality for an entire species, with the Kolmogorov complexity of every object adding to overall computing efficiency.
A simulation solves a lot of problems (and raises numerous philosophical ones). In a simulation, a species no longer needs to find a habitable planet around a star analog to its home system. Resource scarcity (including food and water) is no longer an issue. Evolutionary changes are no longer an issue (provided this isn't programmed into the system). The list goes on.
AI systems can be employed to protect civs living in simulated reality, but as an added layer of protection, such advanced civilizations would also want to remain hidden. Hence the reason why I suggest they might opt to hide among or near the dark matter halos of spiral galaxies. You heard that silly idea here first!
Matrioshka Brains effectively hide stellar radiation by emitting only interstellar background temperature. Gravitationally (is that a word?), the entire system is hidden among the dense dark matter halo and can be assumed to simply be a part of it. Radio communication would be unnecessary by such a civilization, but if they did need to communicate with other Brains, it wouldn't be done omnidirectionally like we dopey humans do it. It'd be beamed directly to its target and we can only assume it'd be highly, highly encrypted.
If we ever were to stumble upon such a civilization, while minding our own business simply studying a dark matter halo, we can bet the AI systems of that other civ would annihilate us promptly... along with our entire solar system. It isn't far-fetched to say a civilization capable of harnessing the energy of entire stars couldn't also weaponize a substantial portion of that energy when needed. We can show up to "see" us some pretty dark matter, only to realize we're looking down the barrel of a Nicoll-Dyson laser canon... think Star War's Death Star by an order of magnitude.
Whether or not life as simulacra is a life worth, um, living... is up for philosophical debate, and beyond the scope of this blog. But with all that I've written in this two-part series, we have to seriously consider the possibility that yes, our time here is limited, but it can be over a thousand times longer than we've even existed as a species, and be enjoyed here on Earth with our own Sun, in our own neck of the galactic woods.
Whether we attempt to leave our solar system or stay is dogged with Knightian uncertainty. Perhaps knowing our end is inevitable is ok, and doesn't require a call to arms to get the heck outta here. The end will come, but it isn't any time soon, provided we don't kill ourselves in one way or another for reasons that will always be irrational. NASA is already seriously considering ways to stave off supervolcanic eruptions. First proposals are always mocked.. that's the nature of things. But they can and have led to successful final products. We can cooperate and organize efforts to seriously tackle any threats of Earth-bound impactors of any mass. Who knows, when the time comes, we may even be capable of employing some sort of space-based solar shields that not only collect energy from the increasingly-luminous Sun, but also block its excess in order to keep things comfortable here on Earth.
Why leave? I say let's stick around as long as possible. Care for the planet upon which we evolved as best we can. Use our imaginations and blind technological optimism to fuel our inspiration to create new and innovative ways to protect the environment we thrive in.
In my humble opinion, our best chance for extended survival on the order of hundreds of millions of years, is to invest in our minds and bodies. To invest in our planet and all living things in, on, and above it. Let's leave evidence of our existence (minus the twitter feeds to space), and accept that our fate is here, on Earth. As such, let's put our energies into our planet and ourselves to ensure our long-term survival.
We won't be here forever, but what's wrong with that? We don't know what lies ahead... whether for religious beliefs, or beliefs in what a multiverse (if it exists) entails... both assume eternal time (the latter assumes it in both directions). With an infinite amount of time, there ought to exist an infinite number of possibilities... perhaps the end is just the beginning.
I'm not a transhumanist, and find the philosophy of it an almost ideological form of blind technological optimism. But I am a humanist, and I am a realist. I think the best way to preserve our species is to leave our knowledge behind in the form of interstellar spacecraft that carry all that we learned in our time on Earth; our histories, our science, our cultures... music, art, photos, videos... everything. Pass on all that we learned, and all that we were to whoever might find it.
I think Achilles summed it up best in that movie, Troy, when he said, "I'll tell you a secret. Something they don't teach you in your temple. The Gods envy us. They envy us because we're mortal, because any moment might be our last. Everything is more beautiful because we're doomed. You will never be lovelier than you are now. We will never be here again."
Thanks for your readership.