So, very roughly, either life is hard to get started at all (but life started about as soon as possible on earth), intelligence is hard to evolve (although we see many species with intelligent behaviour, if not at human level), or it's in our future (that intelligent life tends to destroy itself).
We don’t even know the paradox is real since we haven’t explored our own solar system enough to rule out aliens or artifacts of their visits in our back yard, nor can we rule out advanced observers intentionally not revealing themselves for any number of rational reasons. There could be an abandoned underground alien base on the Moon and we’d have no clue. We have barely gone anywhere.
If we hit, say, the level of development in The Expanse and still find nothing (no protomolecule haha) then maybe we can say there is definitely a paradox.
There’s also the assumption that there is a single discrete big and dramatic great filter. That’s the Hollywood version. In reality there could just be a continuous probability of failure due to any number of events whether endogenous or external spread across billions of years that amounts to a great filter. The probability per day of “biosphere failure” or some other condition that dooms a potential spacefaring intelligence doesn’t need to be high to amount to a probability near 1.0 over geological time scales.
Let’s say given we are sending our probes and capsules we are probably at least 50% of the way there. If the cumulative great filter were near 1.0 probability of failure this would imply a 50/50 probability of our success. Those are of course made up round numbers just to illustrate how that would work. We have no way to know what the actual numbers are because we have a sample size of one.
The whole thing is just speculation until we have more actual data.
As you say, we don't have enough data to know one way or another, but even when we do, there will still be no paradox.
My favorite hypothesis is that we are early. Due to low metallicity in the early universe it’s possible that advanced life only became likely “recently” (as in the last few billion years) and we are part of the first crop. We may be an early example in the first crop because our planet is particularly friendly to advanced stable life, so maybe a bit of rare Earth mixed in. Most other biospheres might be more hostile and take longer to produce anything capable of space flight.
We don’t see star travelers all over the place because for the most part it’s too soon. There might be a few early birds out there but few intelligences are that advanced yet.
We also now know that the creation of organic molecules is commonplace in the cosmos.
True, we don't get any predictive power from this. We're just exploring the space of possibilities, and there's still a lot of unknowns. I still see value in a thought framework like this to guide that exploration, but maybe there's a better approach?
The hard step was not complexification of life. It was long-term atmospheric oxygenation. It took two attempts, the first one short-lived, and between 3-4 billion years to finally succeed for good.
But yeah, oxygenation is a good candidate. Anyway we don't have that much of certainty about how it happened exactly.
But there are other possible explanations.
About the Great Filter, in principle we can expect the probability of those things to vary by several orders of magnitude, so only one would qualify. All of them being equally unlikely is actually harder to explain than the alternative.
This fact is buried in all the Fermi Paradox discussions because Fermi's point was the implications of his work on nuclear weapons when he brought up alien contact.
It has since been used to make the case for Reagan's Strategic Defense Initiative. Which apparently Elon Musk is now continuing... https://ioc.exchange/@muskfiles
It would need to be so powerful and so precisely aimed at us that firing randomly into the void would be pointless. We can barely detect the most energetic events in the universe like quasars and gamma ray bursts as it is.
And that assumes we could even decode it -- advanced coding uses scrambling techniques that deliberately make the signal look like noise to the uninformed receiver...
https://www.reddit.com/r/ChatGPT/comments/1dgyujd/comment/l8...
Creating a self-sustained ship is not so easy. And there are tons of failures that can happen, especially over the course of multiple generations. And you won't be able to just "beam down" to some random planet once your interflux quantum capacitor and its two backups fail. Unlikely things happen given enough time.
And why would you want to do this in the first place? Would life on such a ship really be all that great? Sounds like the stuff of a depressing dystopian sci-fi novel more than anything else.
Dyson spheres seem completely impractical. Just the sheer amount of materials needed alone, never mind the construction effort and maintenance effort. Dyson himself didn't take it very seriously, and I have no idea why anyone else does either.
As for Dyson spheres, don't take the remark so literally. I simply meant that a galaxy-spanning slime mould would probably be visible to our physics, somehow. Life is an entropy engine. Once it gets going, it really gets going. But we appear to live in an improbable oasis in a vast desert.
> As for Dyson spheres, don't take the remark so literally.
Of course it should be taken literally, because all of this is all about what the laws of nature do and don't allow and the practicalities surrounding that. This isn't an class or discussion about what does and doesn't make a good sci-fi story. And what is a "galaxy-spanning slime mould" even?
> Life on a ship is depressing? You may as well argue that life in hydrothermal vents would be boring.
Yes, it would be. There is no intelligent life living near thermal vents. What an odd thing to say.
Is this perhaps a specific personal grudge against your hometown or a more general dislike of Icelanders?
https://en.wikipedia.org/wiki/Hjalteyri
https://xray-mag.com/content/strytan-diving-icelands-hydroth...
Maybe they reached space but upon finding it inhospitable, decided it’s not worth the trouble. Doing things because they are hard could be a uniquely human trait.
On the other hand, I’ve seen a UAP with amazing abilities. Maybe they are here already but aren’t in a hurry to say hello. Maybe they think we are too primitive to warrant communication.
Maybe their signals are all around us but we don’t have the means to detect or interpret them.
Maybe they only use lasers and fiber optics to communicate.
What I take issue with is the notion that it should be surprising that we haven’t detected them. There are so many reasons why they could be right in plain sight, not even trying to hide themselves, while still going undetected. Those explanations are under appreciated in my opinion.
And it's dark so you cannot see it coming. You'd need very high frequency radar or more likely lidar to detect it and you wouldn't have much time to dodge it. (Not to mention that you have to design that lidar with relativistic effects in mind.)
The density of this stuff is not high but it's not zero either.
Until we can reliably detect a species like ourselves on another planet, it seems very silly to assume they aren't there.
The assumptions on detection all kind of assume that aliens that are much more advanced will have much more obvious signals of emery usage or other detectable signals, but I've never been convinced by these assumptions. Energy usage is likely a logistic curve rather than an ever expanding exponential. There so much room at the bottom for greater efficiency. It also seems quite sensible that a species either eventually copes with equilibrium or dies out due to issues with unchecked growth.
There's SO MUCH energy available here on the earth that we could go for millenia of computational/energy growth while pursuing more efficient systems. The assumptions that lead to conclusions about megastructures are pretty dubious. I could go on at length about that, but I will just leave it at that.
As our species has developed, the time scales that matter to us have shrunk, not grown. I just don't think you can have a single coherent civilization work when relativity places such stringent limitations on communication speed. A super advanced civilization likely evolves and changes on much smaller time scales than ours does currently. It doesn't seem possible for such a civilization to not totally fracture at interstellar scales.
Unless there's physics we don't know about, interstellar distances are probably just not really compatible with a civilization. So, if one exists, its probably a serious rarity within a rarity. i.e. the lack of observable existence of such a noticeable civilization does not make a good argument against aliens in my opinion.
(This also raises for me a fun way to continue Moore's law by making lived experience slower...)
I don’t think this seems right. More realistically, the further back into the past we look, the more we notice people, institutions, and changes operating on longer time scales, partly because our knowledge becomes much less granular the further back we look and partly because slower changes are less noticeable or impressive when examined from partway through without the benefit of hindsight.
Unless you just mean that with improved technology we can now do a better job inspecting and sequencing things that happen very quickly. That’s clearly true, but is substantially unrelated to human-scale goals or the behaviors of larger organizations.
Mathematicians always seem to assume that reality is as simple as a plot on graph paper, but if that were the case we would have had hotels on Mars by now.
Or, quite reasonably, human-like intelligence is special and galactic-scale rare. Do we think every other kind of unlikely life exists elsewhere in the galaxy? If there are definitely other human-like intelligent life forms in the galaxy, then there are even more definitely flying pigs with nineteen legs and wheels on the ends. Does it feel so intuitively correct, considering that? The argument here is "but orangutans ... and crows and parrots ... and dolphins ... and octopuses ... and elephants ... they all abound with the potential to build rockets and electronics and self-replicating space probes. Any million years now, any one of those species could flip into producing lots of ideas and constructions and exploring everywhere." But, really? Sure, they do stuff with sticks and half-coconuts, but is "the parrot/octopus/elephant space program is just around the corner" really a parsimonious extrapolation from observed animal stick-handling?
Besides, nerve cells only evolved once, maybe that was a freakish event. Maybe every other animal in the galaxy is a sponge.
Imagine what we will be able to do with another 1000, or 10000 years of development. Can't see any fundamental reason why we could not ultimately build infrastructure and print up some lifeforms at their destinations.
You need to move 500K hiroshimas a second for 80 kg (175 pounds). You'd also need some pretty fast brakes lest you run into some pretty small things. You also have a really bad recursive problem, at 100% E=MC^2 efficiency, you need to turn 100 kg of mass to pure energy, per second, to move 80 kg. So actually you need to move 180 kg, which requires...etc. etc.
This is the base of this thread, the Fermi Paradox: if it was a relatively quick scaling away, where is everybody? It's "turtles all the way down" to respond that there is no paradox, just imagine us in 10K years, even if we knew for 100% certainty we'll be there in 10K years.
Note the wikipedia article you linked uses "concept" 10 times, the roadshadow was in 2016, and has no updates after November 2017, 6.75 years ago.
There are orders of magnitude of things we can achieve as a species with current technology if we all work together efficiently but we don’t .
We ascribe to aliens a singular purpose that we have never achieved in our history as a species.
Our competitive, acrimonious past is fundamental to our scientific progress (we research more during war than peace) . A peaceful civilization may not reach technologically maturity.
It could also be just that Interstellar travel is not simply be economically viable in time frames that those civilizations optimize for. Ours can barely look beyond a quarter, why do we think any other civilization would plan for hundreds if not thousands of years .
Anyway, the Fermi paradox isn't about finding life on other planets.