'Asymptotic burnout' of planet-scale civilizations may explain Fermi Paradox
royalsocietypublishing.orgI find the idea that unless our civilisation changes its priorities from "unbounded growth" to "homeostasis" then we necessarily will suffer the "asymptotic burnout" comparable to papers written in 19th century predicting New York will drown in horse manure in next 75 years unless the growth is artificially stunted. Although the authors mention the role of periodic innovation as a factor that resets the curve of the resource consumption they dismiss it by stating the frequency of said innovation has to increase with increased energy usage and interconnectedness resulting in a certainty at some point innovation will not be fast enough to delay running out of resources. For this argument to work we have to accept unquestionably that "unbounded growth" has to continue until either a civilisation runs out of resources and regressed or achieves "enlightenment" and shifts its priorities towards homeostasis. To this I say why are they so sure, that as through growth of economic activity we raise our collective standard of living people don't start valuing their happiness over economic output? In fact observations of highly developed societies seem to support that. In addition the birth rate of people declines in modern societies often below replacement numbers so that "unbounded growth" looks really unlikely.
We replaced horse manure as a waste product with greenhouse gases, which produced a local improvement but will very likely put large portions of New York City under water in this century. So based on the evidence accumulated so far, we haven’t demonstrated that we can find our way out of the resource/pollution dilemma. Maybe we will in the future!
We already know how to find our way out. Stratospheric aerosol injection. We don’t need to invent anything new or spend significant sums of money.
We will do it eventually, but only after green democrats finish their “perfect is the enemy of good” lifetime crusade.
"Know" is doing a lot of work here.
> Almost all work to date on stratospheric sulfate injection has been limited to modeling and laboratory work.[1]
At best it seems like a good potential solution that need a lot more study.
[1] https://en.m.wikipedia.org/wiki/Stratospheric_aerosol_inject...
In chatting with someone in the oil industry, he said humanity was undergoing its largest accidental geo-engineering exercise via sulphur containing heavy oil being burnt on ships. Somewhat recently high sulphur content was banned from heavy oil and we stopped that experiment.
https://clearseas.org/en/blog/marine-fuels-what-is-heavy-fue...
For some reason, people really seem to hate it when the rain is sulphuric acid. Also, plants. The experiment ended because of the harms it caused.
We need not wonder. Nature has already given us a trial run.
All this brouhaha over unintended consequences are going to ultimately be secondary to the known and catastrophic consequences of runaway global warming.
Yet another Malthusian paper. Why would a planet’s boundary be the civilization’s boundary? This could be an issue on a super-earth and an inability to leave the rock with chemical rockets but even then… or, as Dr Zubrin would say ‘most dangerous are the people who believe a limit in resources is the reason that we must fight each other’
Many of our civilisations have ended because of resources running out/the environment being broken by their own acts.
I’m optimistic about the potential for technology to, for example, disassemble the planet Mercury into a Dyson swarm and use it to power the direct transit of a fleet of von Neumann replicators to the closest 90% of galaxies in our future light cone; but until we’ve actually built ourselves a self-sustaining off-Earth colony, we can’t be sure we can get to the future I’ve just described before some random thing goes wrong here, including but not limited to a petro-state with nukes throwing a hissy fit and starting WW3.
Which ones? I’ve read this argument for Easter Island most often but that has been questioned many times:
https://www.scientificamerican.com/article/rethinking-easter...
One of the biggest fallacies in human thinking about complex things like civilization is the tendency to look for one cause for any one effect. In reality almost anything that happens in a civilization will have many causes, or even many layers of them.
This makes it hard to reduce things like civilization collapse to cartoon morality tales or just so stories but it also makes it hard to reason about them generally. We seem to be bad at judging when things are actually in collapse.
Case in point, I sometimes feel contrarian for thinking that the US is not in decline. Both the far right and far left push this for obvious reasons but I see a lot of counterarguments.
Indeed. Easter Island is the most iconic, though it's also harder to be sure, and you are correct both to say that this is disputed and to later say that a common cognitive failure is to try to attribute everything to a single cause.
Based on what's in https://en.wikipedia.org/wiki/Societal_collapse, I think many local collapses have this as a contributing factor.
The Khmer Empire (of Angor Wat fame) likely collapsed for many reasons, and one of the possible contributors was ecological. As it's quite a long article, I'll quote:
""" Periods of drought led to decreases in agricultural productivity, and violent floods due to monsoons damaged the infrastructure during this vulnerable time.[40] To adapt to the growing population, trees were cut down from the Kulen hills and cleared out for more rice fields. That created rain runoff carrying sediment to the canal network. Any damage to the water system would have enormous consequences.[42]""" - https://en.m.wikipedia.org/wiki/Khmer_Empire
IMO, the British political responses to the potato famine in Ireland and the many different famines in India are major contributors to their respective independence movements, and hence the fall of the British empire.
Post-Empire, Zimbabwe was seen as the breadbasket of (southern) Africa, but the political choices of Mugabe severely reduced its productivity, and are probably a major contributor to the period of hyperinflation.
Regional issues within nations, the Dust Bowl era of the USA was the intersection of natural drought with the failure of the farmers to adapt to dry farming; if the affected regions had been independent nations rather than states of the USA, I think that would have counted as a collapse.
> We seem to be bad at judging when things are actually in collapse.
Yes, absolutely. Even after the event — From what I've read, the Romans didn't think of themselves as collapsed even when (and thanks to the way it happened, where) we would say that it had; and I still witness British people speaking as though the UK is still nearly the equal of the USA, that "the commonwealth" is a major player, and so on.
I'd certainly believe that ecological stress could be a contributing factor. Perhaps civilizations that are already weak for other reasons like corruption, demographics, etc. are unable to innovate, adapt, substitute resources, or otherwise adjust when confronted by ecological stress.
There's a thesis on the collapse of Rome that argues that a volcanic eruption helped tip it over:
https://www.nytimes.com/2020/06/22/science/rome-caesar-volca...
Not self-inflicted, but still ecological. But Rome was already weak when it occurred.
Because space is really, really unhospitable. We haven't colonized the surface of the sea, the top of montains, nor the glaciers of the Antarctic or Greenland, yet all of them are much more suited to human life than space (and as such, humans have occasionally been there for ages).
Living on Mars is pretty close living on the top of mount Everest, if mount Everest was in the middle of the Pacific and all you have to go there are sailboats that take months. It's not a place to settle. And deep space is even worse!
There will likely be people working away from Earth's orbit in the next decades (like we have people working in boats in the middle of Pacific), before being eventually replaced by autonomous machines. But the idea of space colonization is pure fantasy that doesn't hold any water.
Exactly. And there is so much nonlinearity left to discover even here on Earth, once we get through a number of R&D and commercialization hurdles. Such as for commercial-grade fusion power.
All that deuterium in the oceans represents extroardinarily transformative potential for society. And new pathways for technology. Once we learn how to unleash this energy, Malthusianism won't have the appeal it does today.
This is falling into the same trap. Fusion power is not a panacea. The Earth has a heat budget, where it can only emit so much heat over time (moderated by several factors, e.g. the current crisis with greenhouse gases is that we are lowering the rate at which heat is emitted). You cannot simply build an infinite number of fusion generators to generate an infinite amount of energy without also generating an infinite amount of heat that then gets dumped into the Earth's environment, killing all life in the process.
The whole point is that eventually a planetary population must stop producing more energy. Those that don't, die. At best, you could try to colonize more planets to increase your heat budget. The open question, then, is whether or not interplanetary colonization becomes feasible before or after the point at which energy production becomes do-or-die (or rather, don't-or-die). There is no law of the universe that says it must be so.
> The Earth has a heat budget, where it can only emit so much heat over time
Yes, but it's much higher than most think. We're already creating technology like paints and evaporators that downconvert and upconvert photons into a band of the infrared spectrum that passes straight through the atmosphere and into space. Read up on passive radiative cooling, fascinating stuff:
https://en.wikipedia.org/wiki/Passive_daytime_radiative_cool...
That an interesting technology, and indeed we do have the power to exert some control over the Earth's heat budget, I'm not disputing that. However, it seems plain to me that our capacity for spending the Earth's heat budget will, if left unchecked, always naturally outstrip our capacity to raise the Earth's heat budget (the latter requires long-term thinking, whereas the former only requires greedy short-term thinking). If you have two terms that trend to infinity, as long as one term increases faster than the other, it will dominate the other infinite term.
> The whole point is that eventually a planetary population must stop producing more energy. Those that don't, die.
Haven't read him until now, to be honest, but this discussion and some other recent threads from HN make me really want to start reading Georgescu-Roegen's work [1]:
> He is best known today for his 1971 The Entropy Law and the Economic Process, in which he argued that all natural resources are irreversibly degraded when put to use in economic activity. A progenitor and a paradigm founder in economics, Georgescu-Roegen's work was decisive for the establishing of ecological economics as an independent academic sub-discipline in economics.
There was a HN-er who had some good comments about Georgescu-Roegen in the past, not sure if he's still active (I can't remember his username) or if he'll see this comment to add some further insights.
The problem with this reasonning is that it relies on potential, on hypothetical, on hope.
But the problem is not, it's just physics, and it's comming for sure.
Not attempting to solve it with what we know right now because we might pull off something out of our sleeve at some point doesn't seem neither rational nor scientific to me.
However, if we do tackle the problem, we give ourself a margin of security that we can later on remove if we actually manage to innovate out of out petri dish.
We know how to unleash that energy. It just isn't proven to be profitable (yet).
The reality of why we haven't done more to protect our habitat is far from idyllic.
Well, we know how to unleash it in a really dangerous way. We don't yet know how to get net power from fusion in a way that doesn't involve enormous explosions, though it appears we're getting close.
No. We know how to do it safely. It just requires a large (expensive) machine. The thing we're getting close to is making the machine small enough to make it economically viable.
I'm guessing they phrased it slightly awkwardly and meant net positivity by profitability. Since technically we can release energy via fusion but we always have to spend more energy than we get out.
It was the second paragraph that made me think they were referring to financial profit, but we could well be all in vehement agreement.
That's what I've been thinking about for a while as well. Why live down the gravity well if you don't have to? Some might still choose it, much like some modern people choose to live in the forest. And in space, there is plenty of space for everyone.
By the time we reach space, we won't need these bodies anymore.
Earth biology acutely fits to the gasses, minerals, and temperatures found here. It's not a great solution for space, but it's fantastic for exploiting Earth's energy.
Space distances are also not very compatible with human lifespan. The death thing is bad all around: spend a fourth of life learning and a fourth of life in decline, with no ability to share information directly outside of our slow communication and learning protocol.
The obvious answer is that AI and machines will take over from us and leave our planet in our stead. They won't have our limitations on lifespan and complex biological inputs. They won't take up space or get tired. They can copy and paste their knowledge and not need parents or growing up.
Without the limitations of biology, it won't be hard for them to expand to all corners of the galaxy. Despite Hollywood and Asimov trying to paint the picture of humans living amongst the stars, that's more of a fantasy than Middle Earth.
Where we're going we don't need humans or bodies.
Still doesn’t resolve why we have not come across any signatures of beeping and blipping electronic entities that are not our own in the galaxy.
Maybe they're all around us. Or maybe we're their historical simulation. Not readily falsifiable, but interesting to ponder.
Or maybe we're their historical simulation
I’ve thought the same - intelligent machines are going to be mankind’s legacy. Yet I never once thought of us being developed by another civilization’s machines to better understand their origins. Brilliant!
"in space, there is plenty of space for everyone"
We may not need more space if we live entirely in virtual reality.
This I find a quite plausible solution to Fermi's paradox... after enough technological development the entire civilization just starts living in VR and loses the desire to travel through, communicate with, or affect the outer world.
In fact, we may already be just such a civilization... though without realizing it.
The thing is that unless there's some underlying fundamental principle of reality itself that guarantees that every intelligent civilization turns to VR to such an extent as to completely lose interest in reality, it's still very strange that we don't see the galaxy buzzing with life.
There are just so many planets out there that even a 99.9999% chance of VR obsession taking over a civilization should mean having a very visibly living galaxy.
Personally I think that one of the bigger explanations (I think there are likely to be several layers to the paradox) might be that as civilizations grow they naturally focus on becoming more efficient, which effectively makes them more stealthy. We see this with ourselves, where our radio emissions have gone down in transmission power over time and the switch to high frequencies and digital has made them more akin to noise which does not travel very far before becoming effectively impossible to detect. I think our gradual shift towards sources of energy that pollute less is more of the same.
Similarly, while an early interstellar civilization might expend the vast amounts of energy needed to cross the gulf between stars in biological time scales, a more advanced interstellar civilization has very likely achieved some form of immortality (like giving up biology and becoming digital) and may have no reason to try to be much faster than a rock thrown out by its star (in part because when you're effectively immortal grey goo, even a galaxy worth of energy might be something to conserve to maximize your civilization's survival).
> And in space, there is plenty of space for everyone.
Assuming that we can travel at the speed of light, humanity can expand into a spherical region of space where the radius grows at a constant rate. That is to say, under the most optimistic assumptions, expansion is limited by a cubic growth curve. That is fundamentally incompatible with exponential population growth.
Of course, the constants elided in the analysis above are enormous, but it's a limitation that a galactic species would eventually butt up against.
Space is an unfathomably unpleasant place to move to. Maybe advanced extra terrestrials understand that better than we do.
You mean unpleasant to our current biology and with our current ability to build space habitats. Give it a few hundred years and things may look different.
I think they said that about Las Vegas, once upon a time (before the dam was built, and before air conditioning.)
Abstractly, a planet is just a really really big starship. With technological advances, we could even eventually theoretically move planets.
So phrased in another way, why would one choose to live their entire life in a small starship instead of a big one?
Because of the square–cube law. Planets are an unfathomably inefficient form factor in terms of material use to available surface area/volume ratio.
Counterpoint I’ve been thinking about recently:
Imagine you have a fancy self-repairing spaceship, so good that even accounting for the slow wear and tear of micrometeorites, outgassing, and the motion of feet slowly polishing grooves into walkways, it still only looses 1% of its mass to the outside vacuum every thousand years.
A Dyson swarm of those still becomes a mysterious cloud slowly puffing away from its parent star, and after just 2150 millennia, it’s declined from a Kardashev II to a Kardashev I civilisation.
A planet-based civilisation may live or die, but it won’t burn out quite like that.
The usual definition of starship is a ship that travels between the stars. Earth is stuck orbiting one star so I wouldn’t classify it as a starship. Maybe the label would better suit a rogue planet?
The sun moves relative to the neighboring stars. That means we have periodic close encounters (d < 1ly) with other stars, and effectively the Earth starship argument holds. The lazy way to travel the stars is to figure how to avoid killing ourselves for tens of thousands of years, while the stars come to us. See the list of future close encounters at https://en.m.wikipedia.org/wiki/List_of_nearest_stars_and_br...
The most obvious answer is the most boring: known physics prevents extra solar travel and communication.
No they don’t? Or am I misunderstanding what you meant?
I think cyanydeez is misguided, what he means to say is known economics prevents.....
Of course there is no physics preventing it
> Of course there is no physics preventing it
Physics arguably prevents this from being successful for journeys of any meaningful distance and carrying any meaningful payloads. PBS spacetime did a good video about this recently:
https://www.youtube.com/watch?v=wdP_UDSsuro
It's not impossible, but it's a lot harder than most people think.
That's a very good video, thanks for sharing.
I think it does a great job of highlighting why meat crew on a single vessel is perhaps a difficult proposition.
I think we need anyway a colonizing swarm, not a single ship.
I know this goes into scifi territory, but I can imagine a scenario where compute based caretakers could take the seeds of a human civilization (hibernating or embryos) to a system with human compatible worlds.
I would guess we would populate asteroids before other solar systems, and experiences from asteroid based colonies could probably be replicatable in most hospitable systems.
You need to scout the system pretty well. And send many, many ships with multiple redundancies.
In the future, a payload of perhaps several pounds will allow viral replication of a civilization from that. (Particularly since additional design information can be sent via radio waves.)
Because its fucking impossible to escape the Suns Gravity well with all our stuff
> Because its fucking impossible to escape the Suns Gravity well with all our stuff
It's hard but not impossible. Even using 1970s technology [0]
It’s the “with all our stuff” part that makes it virtually impossible. The amount of energy necessary to move that much mass out of stellar orbit is beyond anything we’ve even plausibly imagined might be posible. If it is doable, it’s going to need an energy source that we don’t even have theories of.
I think the Fermi Paradox is more easily explained by three things.
1. It is possible that self-aware life with the ability to manipulate the environment is rare. Most people assume that self-aware life will build cities, but crows, cetaceans, octopuses, and elephants don’t do so despite having quite a bit of smarts. They lack hands.
2. It is possible that the speed of light is a very real boundary and that cannot be broken limiting the ability of life to spread itself within a life time. As anything that persists spends energy to do so, it may be that living things won’t willingly take the chance for themselves and posterity of living on a ship for many generations.
3. Nuclear war. Most intelligent life is predatory. If you want to manipulate your environment, you also have to focus. Most animals with eyes on the front of their heads that can focus well, are also predators. That predatory instinct creates violence, and that leads to war in pack-oriented social predators. With enough advancement, nuclear weaponry and war may be the rule not the exception.
I wonder why they'd leave their home systems? There's no reason to suspect there's anything out there that they can't make close to home - presumably it's all just mass and energy (which are on some level the same thing anyway). Depending on the type of star they live around (seems like a fair assumption they need a star for energy), it'll run down quickly or slowly, but so will every other energy source in the universe. That is to say that I think the answer to the Fermi Paradox is simple, everyday Nihilism.
#2 assumes we won't develop life extension to the point that they aren't generation starships. I find this an unlikely assumption.
Even if we do, there's no reason to think they would reach us. Shooting a bullet at random possibly habitable world is likely, at Earth or even Sol in particular, no.
Barring some sort of teleportation technology or whatever FTL is, the amount of energy required to travel there in reasonable time is huge.
> living on a ship for many generations.
Thanks to time dilation, with 1g of acceleration you can go anywhere in the galaxy and back in 40 years.
Here's one little trick to quickly estimate the fuel you need to get to 99.9% of the speed of light.
You take the rocket equation and replace the velocity with the "rapidity", which is the inverse hyperbolic tangent of the velocity expressed as a percentage of the speed of light. That sounds like a mouthful, but you can actually estimate this in your head.
The inverse hyperbolic tangent is 1/2 log((1+x)/(1-x)). If you plug in 0.999, you get 1/2 log( 1.999/0.001), which is indistinguishable from 1/2 log(2000). If you ever did rough estimates with logarithms, you know that you only need to remember 2 logarithms, log(2) and log(10). They are 0.7 and 2.3, so log(2000) is roughly 0.7 + 6.9 = 7.6, and half of that is 3.8.
You now apply the classical (non-relativistic) rocket equation as if the final velocity is 3.8 times the speed of light (which is 300000 km/s). That's about 1 million kilometers per second.
If you use the best chemical propellants, you can reach an exhaust velocity of about 5 km/s, so the ratio is about 200000. You take exponential of that, and that's how much fuel you need for each unit of cargo you want to ship. You need to use some multiple precision library, because with normal (double) precision floating point numbers, you will get an overflow if you try to do exp(200000).
But let's say you want to use the VASIMIR engine, that reaches (theoretical) exhaust velocities of 100 km/s. Then your ratio will only be 10000. Exp(10000) is still out of reach of normal numerical libraries.
The even more theoretical fragment fission rocket engine reaches exhaust velocities of 10000 km/s. Now we get Exp(100) which is about 3 followed by 43 zeros. If you want to accelerate a space capsule weighing one ton to 99.9% the speed of light, you need that many tons of fuel (assuming a 100% efficient fragment fission rocket). That's a bit unfortunate, because it exceeds by a few orders of magnitude the mass of all the stars and planets in the galaxy.
provided faster than light travel is possible right? Cause the galaxy is pretty big isn't it?
I think he means that your local time passed will be 40 years, while much longer for the rest of non accelerating people.
And of course I have no idea if the maths check out :)
> And of course I have no idea if the maths check out :)
The galaxy is about 90,000 ly across so a time dilation of about 0.004 is required to get to the 40 yr figure. Doing the Lorentz transformation results in a required speed of 299,790 km/s or 99.999% the speed of light.
Needless to say that this is indeed practically unachievable by any macroscopic space craft. Even if you were able to accelerate a ship to such speed, said ship wouldn't survive the journey as radiation from the blue-shifted light of stars in front of it as well as interstellar particles would destroy any known material.
The burnout-collapse trajectory is another kind of homeostasis, only one with very wide range of variation. Though that produces huge human suffering and lossy cultural transmission so it might be worth avoiding.
But homeostatic awakening is continually underway, from 20th century discourse of technique and enframing to our modern drives for global sustainability. Would it not be wise to err on the side of caution, reaching for the stars at some slowest effective rate (Elons per millenium;) until we know more?
Another concern is civilization may execute both futures parallelly via splitting: where some 'elite' Gosper glider-like sets off from home planet, and the Gosper glider gun remains to reset the cycle. If collapse assumed this is your K shaped recovery.
The Fermi paradox does not overly worry me for some reason. Everything Is just so improbable really.
What if there is no real way to create an advanced civilization without fossil fuels, and the existence of them is more rare than we can estimate?
Something I didn't learn until recently is that coal was only formed because at the time Bacteria hadn't yet evolved the ability to break down that plant matter.
The lignin hypothesis: https://arstechnica.com/science/2016/01/why-was-most-of-the-...
On an energy basis, I'm going to doubt this claim. I know there's a common theory that having all the cheap energy of fossil fuels made modern civilization possible, but I suspect it was more of an accelerator than a requirement.
If you have fire and biomass of some sort-- wood, animal dung, etc-- you can get to steam power without too many problems. That gets you to US Civil War tech levels or so. You can build a basic global national transportation network and start mechanizing agriculture on wood-fired, steam powered equipment.
That would be able to provide the level of manufacturing to start bootstrapping electricity-- likely focusing on stationary turbines around hydropower and geothermal sources once biomass hits scaling limits. You might end up seeing an earlier focus on electric transportation systems because the energy density of coal and oil aren't available. You also get telegraphy and radio from that.
A society with electricity would also be have the footholds to start the development of modern physics and get to the splitting of the atom, and at that point, energy is supposed to become too cheap to meter.
The bigger issue I could see is the chemical opportunities hydrocarbon deposits provide.
I could imagine a society without fossil fuels plateauing at a 1870s tech level because of limitations on material technology-- higher-quality lubricants and eventually plastics being obvious missing pieces. They might be able to build an electric car, but it's going to rely on things like fabric-wrapped wires and mica insulation, and have to be lubed with tallow. This would probably only be a transient state though, because without having to compete with poking for goo in the Middle East, many of the "renewable X to oil" pipelines are economically interesting, so eventually, they do get synthetic materials and fuels, although likely at a high price that causes them to be used conservatively from day 1. Once you get to "abundant cheap energy", this likely ceases to be a huge issue.
I'd imagine that this world would end up looking a lot like ours by a hypothetical "2100 AD" tech level. They built on synthetic fuels and electricity because there was no alternative, and we'll have forcibly transitioned to them because we exhausted the fossil stopgap options.
There is an assumption embedded in the Fermi paradox which is that life might originate within an environment already colonized by life. This is not the case in our experience on earth. As far as we know, all life is related which means that all life descends from a common ancestor.
If intelligent life relatively rapidly (say within 1M years) gains the ability to travel at near the speed of light and consume interstellar resources, then new life would never know. There is no case where you could look up and see a galactic empire because if you could see it then it would have been expanding long enough to reach you, and you wouldn’t exist.
Disagree. Life on Earth showed up about as soon as it could. That says the development of life isn't a likely limit. We see only one form of life because having a head start let it outcompete everything else.
We appear to be alone. That says something (or some combination of things) in the process of developing into a starfaring civilization must have billions-to-one odds against it. It's not planets--we see tons of planets. Earth-like ones don't show up much--but our detection techniques aren't very good at seeing Earth-like planets so we can't conclude much from that. The rapid appearance of life on Earth says that's not a likely barrier. Looking at history we have two candidates: the development of multi-cellular life and the development of intelligence. Both took billions of years on Earth. Note that humanity just squeaked in under the wire, about 99% of time Earth would be capable of evolving intelligence is already past. The sun has been slowly warming, this has driven more CO2 into limestone, offsetting the warming. This buffer has almost pegged, once it pegs solar warming turns into planetary warming and Earth is no longer suitable for species with long life cycles.
If we are lucky we are extreme outliers in how fast one or both of those steps happened and the barrier is behind us. (This shouldn't be discarded on improbability--observer effect. Only a planet where that happened could develop a species that could note the issue.) If not, the limit is in the future. Either we destroy ourselves or we somehow turn inward and ignore the stars. Unfortunately, probably says it's one of the latter.
It is possible for there to be a galactic empire and yet we exist--quarantine hypothesis. There's a galactic empire that strictly avoids any star systems with worlds where life can arise. However, such a galactic empire should be detectable anyway. A star wrapped in a dyson swarm will show a spectrum unlike anything we can see in the sky. From this we can conclude there are no dyson swarms in any part of the universe we can resolve stars. Earth shines in the radio spectrum. An ET pointing a radio telescope at us isn't going to be able to decode much of anything (any more than we could listen to a million voices at once) but they can see the energy.
The very concept of a "Galactic Empire" is flawed as soon as you take scale and spacetime into account. The first major obstacle to the concept is distance. It'd take centuries to get even to the nearest off-world colonies and even simple things such as common time keeping become a challenge.
Communication basically breaks down completely once you get to distances beyond just a few light years: consider a "small" interstellar kingdom within a 100 ly radius. The central world will always necessarily be 100 years (in terms of just time) away from the outer worlds. Something happens on the outer rim, the central world won't be able to know about it until 100 years after the fact.
So in essence, every world that's more than a few (e.g. less than 5 or so) light years away is practically isolated from the rest - both logistically and from a communications perspective. It's very hard to come up with any way of describing such a scattered collection of islands as one coherent civilisation.
Another issue is the colonisation process itself. It's virtually impossible to find a nearby 1:1 copy of a world that matches the point of origin of the civilisation. Therefore, terraforming (a lengthy and resource intensive process) or genetic modification would be required. The latter will occur naturally anyway, since some physical attributes of the target world simply cannot be changed without god-like powers (e.g. orbital parameters and gravitation). This means you'd end up with sub-species pretty quickly that won't share the exact same biology and probably have a very divergent culture as well due to being so isolated.
You'd have to come up with some really strong arguments as to how and why - given these circumstances - even "just" interstellar civilisations should be possible in the first place.
Because it's cheap. You only pay once for one small vehicle [1], and its reproduction at the first destination sets off the whole rest of the process. I wouldn't advise sticking to gravity wells. Or even bothering with them. Subspecies and cultural divergence can be seen as a solution, leading to more innovation that can be shared at the speed of light.
[1] https://www.cambridge.org/core/journals/international-journa...
But micro-scale von-Neumann probes wouldn't be building civilisations either - they'd be l'art pour l'art - building more Dyson Swarms for the sake of building more Dyson Swarms. The paper also only considers microscopic probes "invading" HII regions (i.e. hydrogen-rich star forming regions), not colonising space.
By "cheap" you also left out the author's assumption that "the propulsion system will require a tiny fraction of the total gained mass to convert into energy, which we assume could not be a problem for a Type-II civilization."
So they already start with a Type II civilisation that basically dismantled part of their planetary system to reach that state in order to... build probes that construct more Dyson Swarms? Still doesn't sound like a very compelling argument to me.
The paper also doesn't deal with the actual expansion aspect - only with the detectability of micro probes moving through- and replicating within star forming regions, i.e. not places you'd actually want to colonise - neither inside or outside of gravity wells.
> Subspecies and cultural divergence can be seen as a solution, leading to more innovation that can be shared at the speed of light.
You seem to greatly underestimate the vastness of space. Even a tiny (by Fermi-Paradox standards) interstellar realm would have worlds hundreds of lightyears apart. There's not much use in sharing "innovations" if they arrive after 500 years - not much innovation left after such a long time (unless you assume that one side stops innovating entirely for some weird reason, yet keeps listening for signals), plus it'd become increasingly harder to even keep a common cultural understanding given the temporal and spatial distances. Language changes over time, for example.
My take (which does not involve maths, just analogy with other organisms) is that we are bacteria that eat all that's on a petri dish.
Dying as a species is (IHMO) rather unlikely, except for external factors and a few contamination scenarios. Eating all resources, starving most population, and going back to a pre-industrial civilization. Except for a few living high-tech standards. But with devices, they can use but cannot replace.
Lots of pretty words that translate to "reduce population and living standards or die." If true this is the hardest warning that people refuse to hear. If false it is a way to co-op guilt and fear to sell control. How I wish I knew which it was.
The two are not mutually exclusive.
We all know endless growth with finite resources is impossible. We can innovate do things more efficiently or differently and find solutions to previous limits of course.
The hypothesis in the paper is simply that eventually a civilisation will encounter circumstances in which the timescale to solve it is longer than the time they have to do it. Then they must either achieve a form of homeostasis (and no growth) or die off (or retreat and start again).
The boundary for this doesn't have to be a planet. It could be a solar system, or maybe more than one.
I didn't read it that way. The authors propose "homeostasis" as the alternative to extinction. They give Bhutan as an example of a country that has opted for homeostasis rather than growth; Bhutan has reduced neither living standards nor population.
It seems to be a sociology paper. I find the writings of sociologists impossibly dense and obscure.
I would say they’re inversely related. The more people, the less there is to go around. Even if standard of living continue to go up and have, as a function of the population, the two aren’t intrinsically linked by themselves. However as limited resources become more strained over a larger population, the divide and quality of life, certainly in average, has to go down.
It may not be 10 years, 20 years, or even 100 years away but at the moment we have limited quantities of many resources. At some point these lines are going to cross and it is going to lead to a reduction in quality of life.
Whether or not that will be blunted by trends in developed nations toward negative population growth remains to be seen. Novel technology that lets our resources go farther or allows us to gain new sources via space (asteroid capture or mining on other planets, etc.) could also change the tipping point.
The doom and gloom of Malthusian theory is so far unrealized but I think it is hard to argue that the theory is sound at its base. Whether or not we can keep the lines from crossing is the only thing that keeps it unrealized.
Or: allow population to fall and material prosperity as it is. Note: material prosperity is not the same as living standards, as there is more to life than things.
There is no reason at all to think that 1Bn humans can't live on earth at early 21st C standards more or less indefinitely.
11bn at twice that level.... that's harder to see.
The Fermi "paradox" is such an annoying meme. We have no evidence that extraterrestrial life isn't absolutely everywhere. To think we do is to greatly misunderstand the scale of the galaxy.
Why do you find it annoying? Other than it isn't a paradox of course.
It's not claiming that life doesn't exist, it just provides a framework to discuss the current absence of evidence for it. The "where are they" question.
We have conducted a lot of surveys and found nothing. There was a recent survey of galaxies that looked for Kardashev level 3 civilisations (control over the energy output of a galaxy) and we see nothing. So it seems reasonable that they are no K3 civilisations out there in our light cone.
Simple life might be common, but we can't currently look for that easily, although bio signatures of gases in atmospheres is increasingly possible.
It's also possible that complex civilisations are out there, but we just haven't figured out what that would look like.
It's an ongoing search. The one thing we do know is if it's out there, it's not obvious.
I find it annoying because it's discussed on HN ad nauseam in debates that are speculative fiction at best and riddled with logical fallacies at worst.
Take, for example, the "Chain of Reasoning" section of the Wikipedia page page about the "paradox", which ends with following two steps:
> Since many of the stars similar to the Sun are billions of years older, Earth should have already been visited by extraterrestrial civilizations, or at least their probes.
> However, there is no convincing evidence that this has happened.
The "should" in the first doesn't follow from what goes before at all, and the second is one of the most basic logical fallacies: absence of evidence is not evidence of absence.
And take your own point about "K3 civilisations". Let's lay it out:
1. A "K3 civilisation" is one that controls the energy output of a galaxy.
2. Therefore it would be detectable with our instruments.
3. Therefore the fact that we haven't detected one means there isn't one.
This is just bad reasoning. 2 doesn't follow from 1 and 3 doesn't follow from 2.
The "therefore" in 2 ignores the word "control" in "control of the energy output of a galaxy". It makes an implicit assumption that any civilisation in control of such resources would necessarily do something with those resources that would result in an amount of radiation detectable to our instruments being emitted in our particular direction, whether that's some focused signal directly targeted at us or some massive omnidirectional blast. Maybe they would choose to randomly set off supernova-sized blasts for shits and giggles, but maybe, you know, they wouldn't. For 2 to follow from 1 you need to know that such a civilisation would necessarily produce detectable signals and you don't.
Then, for 3 to follow from 2 you have to assume that every signal reaching our planet that is capable of being detected by our instruments is in fact detected. That is hilariously far from being true. Yes, we have some amazing instruments, including ones that can capture enough light from a nearby planet to do spectroscopy on its atmosphere. But those instruments are not simultaneously pointed in every direction all the time. The exact number isn't knowable but certainly 99 and several 9s percent of the signals reaching the Earth at any one time that we could detect and analyse we are in fact not. You talk of surveys but the idea of "surveying" our galaxy (let alone the universe) sufficiently thoroughly to rule out the presence even of the sort of advanced civilisation that produces vast uncontrolled blasts of undirected energy (and of course there's no reason to think an advanced civilisation necessarily would) with current technologies and funding is laughable.
You can't bootstrap knowledge from nothing. The universe is staggeringly vast and we've barely started to look at it. The knowledge we have at this stage places essentially no limits on the sorts of alien life that could exist or on how widespread it is. If you want to speculate about what's out there, please do. I love science fiction! Just don't pretend it's science and please don't claim certainty when your arguments achieve nothing of the sort.
I can understand being annoyed by logical fallacies in the arguments being made, although I wouldn't point to a Wikipedia article for a good example of it in general.
The K3 argument doesn't depend on directionality. If you use a lot of the energy in an entire galaxy for something you will alter the energy signature in all directions. You would expect more waste heat, and a dimming of the overall energy output. This is just basic physics. It's similar to detection of Dyson spheres or other mega engineering structures.
You can argue that they know physics we don't of course. It's certainly true that absence of evidence is not evidence of absence.
This article claims population growth increases on shorter and shorter timescales, leading to infinite population growth.
If this is true, we should have had baby boom, bigger echo boom, giant boom.
Instead, we had baby boom, smaller echo boom, and now Social Security's about to implode because the original boomers are retiring without being replaced. (Or maybe being replaced by immigrants, which led directly to Donald Trump being elected and the near-implosion of our political system.)
This article might be the basis for an interesting and thought-provoking sci-fi story. But if it's supposed to be a serious scientific prediction of what actual aliens in our own universe are like, it's just embarrassing. If you make claims of supposedly near-universal trends in alien societies and say those claims are basically guaranteed by math and physics, then your claims certainly ought to at least be consistent with what we observe in our one known data point of an actual intelligent civilization (ourselves).
And for the claim of technological population acceleration, actual observation suggests the effect runs in the opposite direction, at least here on Earth.