The Great Filter is the idea that, in the development of life from the earliest stages of abiogenesis to reaching the highest levels of development on the Kardashev scale, there is a barrier to development that makes detectable extraterrestrial life exceedingly rare. The Great Filter is one possible resolution of the Fermi paradox.
https://en.wikipedia.org/wiki/Great_Filter
The Fermi paradox is the discrepancy between the lack of conclusive evidence of advanced extraterrestrial life and the apparently high likelihood of its existence. As a 2015 article put it, “If life is so easy, someone from somewhere must have come calling by now.”
https://en.wikipedia.org/wiki/Fermi_paradox
Personally I think it’s photosynthesis. Life itself developed and spread but photosynthesis started an inevitable chain of ever-greater and more-efficient life. I think a random chain of mutations that turns carbon-based proto-life into something that can harvest light energy is wildly unlikely, even after the wildly unlikely event of life beginning in the first place.
I have no data to back that up, just a guess.
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We’ve been producing noticeable radio waves for a matter of decades. We’ve been capable of detecting even super-powerful, super-deliberate, super-targeted broadcasts for even less time.
And on top of that, it doesn’t look as though our civilisation is going to exist for more than a handful more decades, in any detectable-from-light-years-away form.
The chances of that onionskin-thin slice of lightcone intersecting with that of any other civilisation out there seems ludicrously remote.
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My suspicion is that it’s abiogenesis, but it’s only a suspicion that I can’t have any certainty of
Definitely the simplest answer and aligns so far with out observations.
Nah, I’m willing to bet there is actual physical life in our very own solar system (apart from all life on Earth, of course). Europa’s oceans for example have a decently high probability of hosting microbial life.
Of course, discovering primitive life all around us would be a bad sign the great filter is still ahead of us instead of behind us…
Honorable mention: we haven’t detected alien probes, because intelligent alien societies haven’t begun consuming the galaxy with exponential numbers of self-replicating robotic probes, because that’s just a really bad idea:
Simple workarounds exist to avoid the over-replication scenario. Radio transmitters, or other means of wireless communication, could be used by probes programmed not to replicate beyond a certain density (such as five probes per cubic parsec) or arbitrary limit (such as ten million within one century), analogous to the Hayflick limit in cell reproduction. One problem with this defence against uncontrolled replication is that it would only require a single probe to malfunction and begin unrestricted reproduction for the entire approach to fail – essentially a technological cancer – unless each probe also has the ability to detect such malfunction in its neighbours and implements a seek and destroy protocol (which in turn could lead to probe-on-probe space wars if faulty probes first managed to multiply to high numbers before they were found by sound ones, which could then well have programming to replicate to matching numbers so as to manage the infestation).
Oh my god, that’s such a stupid and simple way to kill a galaxy, but also what a great plot twist that would make in a story. Like the big reveal over why the galaxy has always been at war with itself. Exactly the kind of nihilism I’d expect from an Altered Carbon or its ilk.
Thanks for sharing!
You might like the paperclip maximizer thought experiment
Also an excellent clicker style game called Universal Paperclips
Thanks I have heard of this kind of problem before, just not in an adversarial space war context, with like opposing forces
Capitalism I can imagine how capitalism could be inevitable. I can’t imagine enough controls on it to make it sustainable
Personally? Nationalism & nation states. The longer they stay around, the more likely everyone is to think they’re more deserving of X, and pull the literal and metaphorical trigger that leads to hitting the filter.
I recognize that individuality is very much our thing, but that will literally only take you so far.
Life finds a way to end itself. There’s an ongoing mass extinction event caused by humans. Completely preventable by the way. But we do not prevent it.
We actually spend a great deal of effort preventing it. Environmentalism is a really big thing these days.
But even if we didn’t, it’s not an extinction event for us. Humans are actually doing extremely well.
We’re still new to the game, and we have no idea what we’re looking for.
I always thought my Pür was great. /s
There’s been at least 5 mass extinction events we are aware of where I think over 80% of all species become extinct. I’d probably guess one or more of those could do the trick.
I read an article about Fermi paradox (I cannot find the link) that stated the humans are one of the first intelligent beings in the universe. That’s why we haven’t encountered any green men so far. We just might came too soon to the party.
Definitely possible. I’ve read that the projected end of our sun is a “black dwarf”, and that our sun’s generation of stars is so young that there currently aren’t any known black dwarf stars anywhere in the universe.
There is a great video about the Great Filter by Kurzgesagt/In a Nut Shell. If I remember correctly, in it they say we can guess at which stage the filter is by how evolved extraterrestrial life forms are. So it’s actually great if we find a lot of bacteria or other primitive life forms, that would mean we probably already have overcome the Geat Filter on Earth. On the other hand, if we find many alien ruins of several civilizations at or above our technological level… Well, our greatest challenge might be coming.
I like the “Dark Forest” theory I learned from the Three Body Problem books. Basically it’s dumb for civilizations to make a big footprint and reveal themselves because other civilizations won’t know how powerful and dangerous you might become, and so out of precaution they might just zap you. Ironic and over dramatic, but just because that’s a possibility it might be wise to keep a low profile and not invite trouble.
The “Dark Forest” is fine for a scary sci-fi series, but it has many flaws that make it unrealistic as a real solution to the Fermi paradox.
- Earth has been quite obviously life-bearing for at least 2 billion years. We should have been wiped out long ago.
- The book series made up fantasy magic tech for how exactly a civilization can be destroyed by another without giving away their own location. I’ve yet to see an explanation for how that would be done in reality that doesn’t give away the attacker’s location.
- It doesn’t explain why nobody has colonized the galaxy.
I think others wouldn’t bother with us until we started demonstrating likelihood of using dangerous tech or crazy exponential expansion.
I don’t remember well, but I think civilizations stationed their defensive or offensive tech away from their own civilizations, just dispersed around.
I think its explanation for why no one or anything has colonized the galaxy though is that if anyone shows signs of becoming that strong, they get zapped. Nobody wants to see a neighbor rise up into a behemoth, you get that bold you’re a threat.
My real preferred theory of why we don’t see other civilizations though is that I think they choose more inward, VR, computer-based evolution that doesn’t result in big mega structures.
I think others wouldn’t bother with us until we started demonstrating likelihood of using dangerous tech or crazy exponential expansion.
Why do you think that, though? It doesn’t make sense, frankly - if you’re worried about competition evolving you shouldn’t wait until the last possible second to destroy it. That raises so many unnecessary risks of being slightly slow on the draw, and then it’s too late. Why not do it at the earliest convenience, when it’s super easy to do by comparison and there’s an incredibly long margin of error if you somehow miss the first couple of tries?
I don’t remember well, but I think civilizations stationed their defensive or offensive tech away from their own civilizations, just dispersed around.
I think its explanation for why no one or anything has colonized the galaxy though is that if anyone shows signs of becoming that strong, they get zapped.
But they’re already doing it, you just said they’re putting outposts out there. If they can’t do that secretly then the Dark Forest doesn’t work in the first place. Placing a secret weapon base in another solar system is no different from placing a colony there.
My real preferred theory of why we don’t see other civilizations though is that I think they choose more inward, VR, computer-based evolution that doesn’t result in big mega structures.
As with many Fermi paradox solutions this one fails on account of requiring every single civilization (and every single subset of those civilizations) to all decide to do exactly the same thing, forever, with no exceptions. In a scenario like this what happens if a single subculture of a single advanced civilization decides for whatever reason that they prefer not to do that? They would be able to spread throughout the cosmos without opposition, everyone else is locked in their little dream boxes and therefore is basically irrelevant. It only needs to happen once, and the universe has been around for a very long time.
I’ve never read the three body problem (started it but just couldn’t finish…it was very slow paced and there were moments when the Chinese…I don’t want to call it propaganda but more like promotion…took me out of it, like the supposedly international coalition of scientists where the non Chinese ones were just cardboard cutouts) but I can speak to this:
The book series made up fantasy magic tech for how exactly a civilization can be destroyed by another without giving away their own location. I’ve yet to see an explanation for how that would be done in reality that doesn’t give away the attacker’s location.
Relativistic missiles. Nothing moves faster than the speed of light. So if you can get a big rock to go 95% of the speed of light, we’d only be able to detect that it’s coming right as it hits. Sure, you can calculate the origin of the missile after it obliterates its target, but it’s almost impossible to form a counterattack especially if the attacker just yoinked an asteroid from a different star system than their own and strapped an engine on it. And ESPECIALLY if your civilization is still mostly planetbound.
And a rock moving at some appreciable fraction of the speed of light could obliterate the Earth.
Relativistic missiles. Nothing moves faster than the speed of light. So if you can get a big rock to go 95% of the speed of light, we’d only be able to detect that it’s coming right as it hits.
This is a very common answer to “how”, but it comes with lots of problems in the Dark Forest context.
- If you actually calculate how much energy is required to boost a big rock up to that speed you run into lots of difficulties. It takes a lot, a heck of a lot. How does a civilization that is “hiding” accumulate that energy? How does it store it long-term?
- How is that energy actually put into the rock? This is basically a starship accelerating up to that speed and getting a starship up to that velocity is not easy even if you have the energy available. Does it have a rocket? The rocket equation for getting up to near-lightspeed requires ridiculous amounts of propellant. Is it beam-propelled? You’re not being at all stealthy that way. How much acceleration can you get out of your system? It takes a full year at one Earth gravity of acceleration to get up near lightspeed, and that’s a really high acceleration - you generally trade acceleration for efficiency so the faster you want to get up to speed the more energy you need and the noisier you’ll be.
- It actually is possible to counter an RKV. It’s much easier to hit and destroy an RKV than it is to launch it, all you need to do is get a pebble in its path. The key is detection, and the above points give some pretty good options for detecting it before and during launch. That gives you time to fire your countermeasures.
And ESPECIALLY if your civilization is still mostly planetbound.
Absolutely not guaranteed to be the case. Earth’s civilization could have easily had offworld colonies by now if circumstances had been slightly different, so a Fermi paradox solution that requires reliably blowing up Earthlike civilizations before they can get offworld doesn’t work. They’re already too late.
As I said previously, Earth has been quite obviously life-bearing for at least 2 billion years. Why wait until something like an RKV is needed, and even that is not guaranteed? They could have destroyed life on Earth far easier, and thus far more stealthily, if they’d done it a billion years ago.
I agree, either we’ve escaped detection or the dark forest theory is wrong.
Couldn’t antimatter bursts get an object to extremely high speeds relatively cheaply?
Well, “relatively cheaply” is a hard standard to nail down. I would say “no”, though. Antimatter is very expensive to manufacture and store and you’re going to need a lot of it. All of the energy that comes out of an RKV hitting its target has to be put into it in the first place, probably several times over given the inefficiencies likely inherent in the process.
Fair enough, guess it depends on how many resources they’re willing to sink into first strike capability. Maybe a strongly expansionist civilization would have such a more efficient use of resources it would quickly catch up to a dark forest predator trying to wipe them out. Like a swarm of piranha eating a shark.
Earth has been quite obviously life-bearing for at least 2 billion years. We should have been wiped out long ago.
I believe the theory is that as civilizations broadcast a signal indicating life exists strong enough such that it is picked up by other civilizations, the dark forest theory applies. Essentially we haven’t broadcasted a signal loud enough to be picked up
But that’s not actually true. We’ve been “broadcasting” the fact that there’s life on Earth in the form of the spectrographic signature of an oxygen-rich atmosphere, which is a clear sign that photosynthesis is going on. There’s no geological process that could maintain that much oxygen in the atmosphere. The Great Oxidation Event is when that started.
We have the technology to detect this kind of thing already, at our current level. Any civilization that could reach out and attack another solar system would be able to very easily see it.
This is quickly becoming beyond my knowledge pool, but does this assume that all life is intrinsically linked to oxygen?
It’s not specifically oxygen that’s linked to life, it’s chemical disequilibrium. Oxygen is highly reactive, there are lots of minerals that will bind it up and there aren’t any natural geological processes that unbind it again in significant quantities. If you put an oxygen atmosphere on a lifeless planet then pretty soon all of the oxygen will be bound up in other compounds - carbon dioxide, silicon oxides, ferric oxides, and so forth. There has to be some process that’s constantly producing oxygen in vast quantities to keep Earth’s atmosphere in the state that it’s in.
There are other chemicals that could also be taken as signs of life, depending on the conditions on a planet. Methane, for example, also has a short lifespan under Earthlike conditions. You may have seen headlines a little while back about the detection of “life signs” on Venus, in that case it was phosphine gas (PH3) that they thought they’d spotted (turns out it may have been a false alarm). These sorts of gasses can be detected in planetary atmospheres at interstellar distances, especially in the case of something like Earth where it’s quite flagrant.
Even if these are sometimes false alarms, in a “Dark Forest” scenario it’d still be worth sending a probe to go and kill whatever planets exhibit signs like that. It’s a lot cheaper and quieter than trying to fight an actual civilization. That’s why I can’t see why we wouldn’t have already been wiped out aeons ago in this scenario.
Thanks! That’s a different way of looking at the problem that I hadn’t considered.
Tbf we are noises as fuck. We’ve been sending so much out for decades.
Sure, but it’s just small game chatter. We start building a Dyson sphere powered starkiller cannon or some such nonsense we might pop up on somebody’s radar.
The problem for the Fermi paradox is that there’s no reason to do stuff like that before we start colonizing other solar systems.
Also, how do you destroy a civilization that has a Dyson swarm already? That’s not exactly an easy task, and if you insist on remaining stealthy yourself it’s nigh impossible.
The galaxy is a bowl of M&Ms. One of every hundred M&Ms is poisoned and will immediately kill you. It’s only a 1% chance you’ll die. Well maybe pike 5% if you eat a handful.
Most of the civilizations might even be moral enough not to destroy us, but all it takes is one.
Yep exactly. Who knows how murderous other civs might be, maybe they’re nice but maybe not.
How do they do it, though? It’s not really a valid solution unless you can explain how it works, otherwise it’s just “maybe some magic happens that kills civilizations.”
Once a civilization has begun spreading to hundreds of other solar systems I have yet to hear of any plausible way to reliably “kill” it.
Guns? Bombs? Surely you can kill a civilization. Not sure why magic would be required.
I think that for a technological civilization to rise, you need some things to line up. First, life has to be evolved enough to have animals, beings with a brain. Then, a species has to evolve intellence to become a tool making species. This species also has to become the dominating species on the planet. Meanwhile, extinction events, ice ages, climate change and population bottlenecks are always influencing the evolution process.
This is for me the great filter, to have all these conditions line up perfectly for an intelligent, tool making species to evolve and thrive.
I think most lifeforms will have more pressing matters than wasting large amounts of time an energy blasting signals in to space for no reason, or listening to the sky.
Maybe those civilizations that waste more energy chasing aliens die off sooner due to wasting resources on sci-fi bullshit and ignoring their real problems at home.
I disagree. I think there is no more important thing we have ever done or will ever do as a civilization, than try to make contact with alien life.
My guess would be self-replicating biological organisms capable of significant rates of mutation.
But then my preferred solution to the paradox as a whole is basically the “nobody tries” idea.
I don’t think there’s tremendous reason to try to make ones-self detectable at long distances. It’s an expenditure of non-trivial resources for an uncertain result. Since there isn’t really any robustly sound logic for making the attempt outside of dramatized sci fi stories, I imagine a vanishingly small percentage of occurrences of intelligent life would make a serious, high-powered attempt at any point.
I don’t really subscribe to the theory, but I think the idea that alien races are all like “go to SPACE? Why the fuck would we do that?? It sucks up there!” is definitely the funniest solution to the Fermi paradox.
