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.
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.
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.
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?
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.
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 agree, I don’t think they’d wait until the last possible moment when the civilization becomes super powerful or builds the mega weapon. I just mention it along the range of development to highlight the why.
I think they might let weaker civilizations keep going, though, just out of hope they wouldn’t be too mean. Also, zapping other civilizations when you don’t need to exposes yourself and your own aggression.
About the shift to VR /computer substrate worlds that wouldn’t have huge footprints, I agree that not all would do that, and it only takes one to go the big building and footprint route and it’s weird we don’t see it.
My guess then would be that maybe they do build big, but they just conceal well…? You get good enough tech at some point you can choose to be hard to see.
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.
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:
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.
This is a very common answer to “how”, but it comes with lots of problems in the Dark Forest context.
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.
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.
Military Industrial Complex: “Hold my beer”
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.
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 don’t think you’ve thought through the logistics required for the sort of war where you’d just go around and shoot everyone who lives in hundreds of solar systems. Even assuming they do nothing at all to defend themselves, how do you even find them all?
Yep exactly. Who knows how murderous other civs might be, maybe they’re nice but maybe not.