Beyond “Fermi’s Paradox”: The Percolation Theory Hypothesis
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I'm not sure any of these assumptions are applicable given billions of possible origins of life at various stages of development. Even at Earth, and with extremely conservative estimates, given 100 more years of nanotech/biotech/AI development, we won't die off, and could certainly send autonomous robot probes. When you don't die anymore, 8 years roundtrip (or more) suddenly doesn't seem so long.
BTW in the fiction arena, I suggest reading David Brin "Existence" if you're so inclined which is related to this :)
I'm not sure certain.
Cost is, at its core, based on physics- energy, resources and time are the true values all money is based on. Those constraints will exist everywhere in the universe, however they may be treated by an ETI. No matter where you go or who you are, you still need a massive amount of energy to move matter from one star to another.
It's not even obvious that it is theoretically possible with current circuit technologies. Pieces would fuse together, moving parts would erode, all sorts of organic materials might deteriorate, everything would be affected by the huge amount of time. And you would almost certainly need energy to actively fight this entropy so that you would have an active machine when you reach your destination.
Iron is nuclear ash, and this tech is just about the most reliable implementation of logic we have. It was used in the V2 rocket and US nuclear submarines. It's abandoned tech though and was never pushed beyond 1MHz. If however you have a decade to compute your reactions then that might not matter.
Superconducting magnetic loops also store their flux indefinitely, and in space keeping it cool would be trivial.
The real problems are political, technological and ecological stability.
No one has ever built electronics capable of lasting hundreds of thousands of years. It's not obvious if it's possible because on those timescales everything crumbles to dust, especially if it's constantly being abraded by dust and radiation.
And if you don't put your travellers into long-term suspension, political and cultural stability are even more fragile.
And small eco-systems are far less resilient than planet-sized systems - which, it turns out, may not be resilient at all on longer timescales.
So the gap between launching Voyager I/II and launching a self-replicating probe which can reproduce itself physically and culturally is beyond huge.
If you happen to have massive amounts of energy some of these problems get easier, because you can get where you're going more quickly. But some remain immensely difficult.
Which is why percolation is a much better model. There will inevitably be some attrition in any colonisation program, and there may well be a hard limit on the amount of entropy any colonisation program can survive.
Might as well ask Archimedes to send a probe.
Hell, I'm not even sure we can make a computer that actually lasts 100 years.
I'm pretty sure we can. I have a 40-year-old calculator that is still working just fine.
Still, I was probably too ambitious when I said "computer". I was thinking more that we can't make a PC or server-style computer that would actually last 100 years, while in regular operation.
Also, 1980s calculators have much, much fewer moving parts than today's computers. They don't have any kind of active cooling, they don't go through rapid heating and cooling cycles, they probably have three orders of magnitude less electrical components than a modern PC.
For me at least, all of the PCs I have had so far have had a few electrical components giving out after at most 10 years (usually some condensers leaked).
In fact, it would not surprise me a bit if you could run a Raspberry Pi Zero for 100 years.
I wouldn't even be convinced then that we have the technology today. Any repair system would necessarily suffer from the same kinds of failures.
The distances in the milky way are mind boggling. But the age of the Earth is even more so.
Now imagine a people as far advanced of us, as that ant is to you. Now imagine that 10,000 times more advanced. Or 100 million times more. That is the kind of difference we have to consider.
The unfortunate reality may be that other civilizations are so far advanced from us (100x? 10,000x? 10 billion?) that we are effectively 'alone' all the same. Like an ant pondering the garden hoses, BBQs, or fence posts of the universe.
During that time, the population of Europe increased as well - many people just thought that America was a better place to live.
There's no need to wait for "full saturation of a star system" to send out probes and colony ships.
I made the point in another comment but I do think there has to be a reason to send out colony ships. I agree that exploratory, unmanned probes would be sent out to gather information but I doubt sustained efforts to colonize new star systems would be made until there was significant social, political, or environmental pressure to do so. One ship colonies never succeed beyond a toe hold, you need a constant flow of people, resources and information to drive the founding of a new civilization especially if the trip is one way with little possibility of trade. If all you needed for the development of a new culture and society was an initial seed population and time then every town in the world should be a New York.
Mind-blowing universe, amazing planet, very little time sadly.
The main reason that farmers outcompete hunter-gatherers is that agriculture allows building larger societies than hunter-gathering can, and this extra population gives a decisive advantage in being able to prosecute wars for as long as is necessary to exterminate hunter-gatherers.
Thinking about this a bit deeper, this is only true if you have a small population with relatively plentiful resources. Hunter gatherers quickly bump into the limits of their environment if their population increases. The idealization of their lifestyle is misguided because it would necessitate drastic reduction of population levels to reach that balance. The goal should be to increase the abundance of resources in our modern environment so that we reach the same ratio of resources to population, which hopefully would mean a consequent reduction in the amount of effort we have to expend to obtain those resources.
"Let's just stop doing anything regarding climate change because in 50 years we'll have the tech to solve it, we don't know it yet because we can't imagine it."
At some point, as a specie, we certainly can't afford to gamble our survival and culture like that.
If I launch a rocket now, it’s will take 50 years to get to Pluto. If I wait 10 years, we’ll have faster rockets, so it will actually get there sooner. The progress of my original rocket cannot be improved.
For global warming, progress we make now can be built on and improved over time. This is not the case with a rocket that’s already launched.
That's because my argument is not about rockets or climate change but about underlying assumptions.
> If I launch a rocket now, it’s will take 50 years to get to Pluto. If I wait 10 years, we’ll have faster rockets, so it will actually get there sooner. The progress of my original rocket cannot be improved.
Faster, maybe. Sooner ? Where is the proof ?
And what if you can build a faster rocket only because you learned from mistakes from the slower first rocket ? If you never launch and experiment with that one in real conditions then you may very well never have a faster rocket.
Let's put it another way:
- before, we didn't know how much was feasible and we doubted we could do better (LEO, moon landing, etc.).
- Now we know we could and did.
- So we think in the future we'll be able to do things we can't do now.
- But what if we are wrong again (like we were before) and that very belief is wrong.
- You can still think/believe things like “Assuming constant progress in technology we might be able to get there faster by waiting decades than by leaving now. Even the absolute limit of light speed, while impossible to imagine today, might turn out to be less of on obstacle in some future understanding of physics.” but that belief may very well be our mistake, just like people 100 years ago didn't believe we could land on the moon.
Now we just believe anything is possible.
Then there is the potential of things like hibernation, or AI that can just turn itself off. The latter would be able to use a less costly but slower propulsion system.
I really don’t think travel implausibility works as a Fermi paradox answer. It’s hard but not hard enough to explain the absence of visitors in a galaxy full of planets in habitable zones.
I wonder how much such a mission would cost in terms of total Earth resources. I've read Dyson's book on the project some years back and I don't remember that being mentioned.
Wikipedia states the cost in percentage of U.S. GDP (0.1 - 1% of yearly GDP), but I feel like the millions of tons of copper and fissile material required would be significant hit on remaining mineral reserves. It's kind of hard to justify sending out a few missions if it means that the planet left behind is out of easily mined copper and uranium deposits.
We could probably send a probe to Centauri for the price of one Iraq war.
Of course launching “the devil’s pogo stick” from within our biosphere would be rather horrible for the environment. It would be a lot better to build a base on the Moon and launch it from there. You wouldn’t need to burn as much power getting out of a big gravity well. The Moon, being formed from the same stuff as Earth, certainly has fissile material, and it may be closer to the surface and easier to get there.
I really think the most likely answer to the Fermi paradox is that extreme intelligence is rare. There probably isn’t a single great filter per se. It’s probably just unlikely for an environment to be simultaneously stable enough over billions of years to produce high intelligence and interesting enough to stimulate its evolution. Most interesting environments will be unstable, and most stable environments uninteresting (a.k.a. having low Shannon information content).
The universe is probably full of microbes, simple microbial colonies, and maybe a few worms and bugs, but there are probably not very many minds around capable of harnessing the atom and plotting orbital trajectories. Fewer still may have the motivation to invest in such an epic and likely one way journey.
For the latter point keep in mind that solar systems are huge. There are enough bodies and resources in our solar system to keep even a spacefaring humanity busy for millions of years. No necessity to travel to the stars for quite a long time. Space is called space for a reason.
Pricing planet-sized stuff like this in monetary value is problematic.
Taking figures from a quick Wikipedia search, "one Iraq war" buys you 10 years of world copper production at current rates. That is a non-trivial portion of planetary minable reserves, estimated at "from 25 to 60 years"
That hasn't been demonstrated. Project Orion was canceled before critical parts of technology were actually tested, and the mechanical viability of a pusher plate that has to absorb the impact of several nearby nuclear explosions in rapid succession is somewhat doubtful.
They did do some survivability experiments at ground zero at atomic tests and found that some materials could stay intact. I recall reading that the biggest problem on paper for Orion was cooling the plate in space so it wouldn’t melt after a few pulses. I think they posited various ablative shielding materials plus some kind of active cooling. Of course also remember that once you are in space you don’t need to fire rapidly. One boom every hour or two or even longer would be fine. It could take quite a while to build up to cruising speed, and to decelerate.
Acceleration would require several times more charges since you have to accelerate all the deceleration fuel. With interstellar flight you have two massive problems: going fast enough, and then slowing down at the other end.
100 more years of R&D is not very long on geological or cosmic time scales. My point is that the math working for something as brute force as Orion makes the difficulty of interstellar flight a problematic answer to the Fermi paradox.
1. Interstellar travel is genuinely hard, so hard that advanced civilizations do it from time to time, but not so often to result in "percolation". In order to have a reasonable argument, let's start from contemplating how hard it would be for us, humans. This is the only civilization we know of at this point. There are two things that make interstellar travel very difficult: 1.a. potential collisions with dust grains and 1.b. violence.
1.a. Danger of collisions. According to wikipedia, cosmic dust grains can have a size up to 500 microns. At a typical density of 2g/cm3 this is a mass of 0.5 mg. Assuming you have a spaceship that travels of 0.01 the speed of light, the energy of impact with such a dust grain will be about 20% the energy of an armor piercing round shot from a modern main battle tank such as the M1 Abrams. Over a 4 light year travel (the distance from us to the closest stars), or a few hundred years of flight at 0.01c, there would be billions- trillions of such impacts.
1.b. Human violence. Assuming we get the technological prowess to accelerate things to 0.01c, what's to stop someone to point a little projectile in the direction of Earth, or some other place colonized by humans? Such of projectile weighing only 15 kg would have the energy of the Hiroshima bomb. In fact, it's actually most likely that the road to interstellar travel will start from military applications, just like the Apollo program was a side-effect of the arms race that created the ICBMs.
2. Interstellar communication is hard. Let's say that aliens are indeed everywhere, including in the planetary systems of our closest galactic neighbors. How would we know? Would SETI find out about that? The only way we'd find out were if they were pointing some large antennas straight at us, and putting some megawatts of power into beaming signals at us. How do we know that? We know because we get radio signals from Voyager 1, which is 150 AU from us. Proxima Centauri is 1700 times further, so the signal would be more than 3 million times weaker. Voyager's antenna is 3.7 meters and the transmitter has 22 W of power. So, if our neighbors are not actively trying to beam signals at us, our chance of detecting them is practically nil.
1.b. Space faring civilizations probably don't live on planets the same way we no longer live in caves and mud huts, they build modern houses and cities out in space near to their preferred energy sources and transportation networks. It's a lot harder to hit something smaller and more mobile than a planet and even if you do it doesn't have the same consequences that it would on the ground. i.e. more likely to just punch a big hole rather than convert all its energy to heat, no pressure wave, your neighbours are further away, etc.
2. This is probably why we don't hear anyone, either they are smart about their use of EM communication and everything high powered is directional or they are even smarter than us and have figured out some form of FTL communication.
Whatever protection system one comes with, it would better be good 100% of the time. Because a 99.999999% success rate will be a death sentence.
> It's a lot harder to hit something smaller and more mobile
People are very inventive when it comes to new weapons. By the time we have the technology to reach 0.01c, we'll have invented 10 more generations of weapons. We might miraculously avoid interplanetary wars before we reach for other stars, but I would not bet my money on that.
[1] https://en.wikipedia.org/wiki/The_Five_Ages_of_the_Universe , more dramatically portrayed in this excellent video: A Journey to the End of Time [2]
https://scitechdaily.com/star-formation-in-the-universe-has-...
Moreover, life originated early on Earth. This suggests either that more than one extremely rare event is needed to get from life to us, or that the conditions for OoL do not persist for very long (ammonia, for example, is rapidly destroyed by solar radiation.)
https://www.universetoday.com/feed/?s=%22Beyond+%22Fermi%27s...
Or you can broaden the list with some additional articles tagged as related to the Fermi Paradox with:
https://www.universetoday.com/tag/fermi-paradox/feed/
It seems the author publishes every few weeks to months.
https://www.universetoday.com/15403/how-long-would-it-take-t...
And then it would be one of the most significant engineering projects in history.
There maybe some cultures that still see value in the physical world, but I'd wager not many.
I also think it's likely that panspermia is a thing. Life is evolving at the galaxy level, it's therefore a little more reasonable to think that we represent one of the more evolutionarily advanced life forms at the current time.
I'd say that this is also the case for other civilisations, which might be another reason why we don't see them.
https://www.pewresearch.org/fact-tank/2019/06/17/worlds-popu...
Similarly for other problems that can block interstellar travel (bureaucracy, nuking themselves, etc).
If space was easy then our galaxy would have been devoured by some grey goo AI (not life) a long time ago. Life has to build artificial habitats and live in them. AIs can just stay in space forever as long as they can gather enough resources.
Space colonisation with current tech isn’t a joke, but it is a folly in the sense of British Victorian-era aristocrats — extremely rich people doing fancy but not very cost-effective things.
Fusion isn’t necessary for this, however, as PV scales well enough for a Mars colony (don’t get me wrong, still extremal, but it could be made to work up to about Jupiter if cost of local manufacturing was not a limiting factor).
But: politics. Let’s assume every settlement on Earth has a corresponding space habitat (O’Neill cylinder or whatever) of the same population in Earth orbit. With this situation, rapid transport between any two locations is trivial enough that high school students could accidentally blow everything up up — I made an ion drive while at school (simple ones are easy) but orbital dynamics are counter-intuitive and not something a high schooler is likely to know, so a kid running one in space with that many large stations around has a high risk of causing a Kessler cascade.
Scale the hypothetical scenario up to a K2 swarm around the sun, same applies only with the risk of mass extinction on the home planet.
In either case it can be weaponised, and about 19 years ago a bunch of theocratic fundamentalists demonstrated that a small group of humans can be smart enough to cause enormous harm while also being dumb enough to not predict the consequences.