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We again return to the rabbit hole that is the Fermi Paradox [1]. In short: there are so many stars and planets and we've had billions of years. Why aren't ther

by cletus 4y ago

We again return to the rabbit hole that is the Fermi Paradox [1]. In short: there are so many stars and planets and we've had billions of years. Why aren't ther emore signs of technological life? A core idea of this is that there are various filters that separate a new planet from one hosting spacefaring life. There are lot of these filters proposed. One category is the Great Filter. These are where very few lifeforms are expected to pass. So what we're talking about here is an early filter where a planet forms in a relatively stable and suitable star system and single cellular life forms. Based on our own understanding of biochemistry, that pretty much requires amino acids. Now there might be other forms of life out there but they're all theoretical. We have one which is real (ie ours). We've had a lot of experimentals that show that amino acids can form in deep space on icy bodies. What we have here is direct evidence from an essentially random asteroid that it has amino acids on it. We can and will speculate as to the origins of these. Did they form on the asteroid? Elsewhere? When? You can't obviously draw too many conclusions from a single data point but to suggest we got extremely lucky to find the a super rare asteroid with amino acids on it stretches incredulity. So the conditions that lead to life similar to ours forming being relatively common only gets stronger. This is similar to the number of expoplanets we've found. We've shown that planetary systems are exceedingly common, which was something we could only speculate about a mere 40 years ago. More planets, more conditions for life forming. This means more species are likely getting filtered further down the chain. [1]: https://en.wikipedia.org/wiki/Fermi_paradox https://en.wikipedia.org/wiki/Fermi_paradox

JumpCrisscross 4y ago
> more species are likely getting filtered further down the chain My personal hunch is the filter is around multicellular life. We'll find lots of planets with single-celled goop. Many fewer with animals. The unions that created photosynthesis and mitochondria look to have happened only once (successfully) in Earth's history [1], and sound more like voodoo than science the more one thinks about it. (Cell ate another cell then changed its mind and adopted it for 1.45 billion years.) [1] https://www.nature.com/scitable/topicpage/the-origin-of-mitochondria-14232356/ https://www.nature.com/scitable/topicpage/the-origin-of-mito...
- cletus 4y ago
  The earliest signs of life at >3.5B years old [1] while photosynthesis dates to ~3.4B years ago. That seems to be pretty quick (by some definition, ~100 million years with huge error bars is "quick"). If photosynthesis only evolved once, another explanation is that it only needed to once because it was so wildly successful. Multicellular is interesting. That obviously took much longer but once it did? Holy crap did things take off. I kinda wish I could have a time machine just to visit the Cambrian Explosion era. [1]: https://en.wikipedia.org/wiki/Evolution_of_photosynthesis https://en.wikipedia.org/wiki/Evolution_of_photosynthesis
lumost 4y ago
While we're speculating, allow me to throw my 2 cents in. The biochemistry of life is likely to be common, the conditions for complex or even intelligent tool using life are likely to be rare. To have an earth, you need to have a moon comparable in mass to the planet to avoid atmospheric stripping. A temperature regime stable enough to support long term life development between 0 and 100 C. A star that doesn't blasttge planet in radiation every few thousand years. Along with a reasonable balance of materials, and a stellar neighborhood which wont swing the balance too badly every few million years. Lastly, although untested, To have tool use, you likely need a planet with gravity thats strong enough for the atmosphere to be stable, but weak enough for organic molecules to hold together complex life and enable the construction of material objects. A super earth covered in algae is interesting, but may not be capable of traditional human intelligence.
- EForEndeavour 4y ago
  > To have an earth, you need to have a moon comparable in mass to the planet to avoid atmospheric stripping. Could you elaborate on this? I'm aware that magnetospheres protect atmospheres from solar wind stripping (e.g., https://science.nasa.gov/science-news/news-articles/earths-magnetosphere https://science.nasa.gov/science-news/news-articles/earths-m...), but have never heard of the role of moons, and can't find anything via Google right now.
- pasabagi 4y ago
  My preferred speculation is simply that faster-than-light travel is impossible, so all the tool-using aliens out there are not visiting us because they can't, and we can't hear their signals because it gets lost against the background noise. I mean, would we be able to detect our own civilization from a few lightyears out? Apparently, unless you're pointing a radio telescope right at something, you woudn't be able to pick up human civilization levels of radio from more than a lightyear out. Say there's one smart tool-using civilization per 5000 lightyear volume, then they're unlikely to meet.
  - spfzero 4y ago
    Even if a civilization out there had faster-than-light travel, they would most likely not know we were here. They would need to decide to come explore near us, probably need to expensively slow down to sub-light speeds to look for signs of life near here and pick up our emissions on some old archaic piece of equipment they happened to bring along. Would a much more advanced civilization spend their exploration budget to look over uninteresting primitives like us, or would they go off in search of other more advanced civilizations like their own?
hnuser123456 4y ago
Consider factors like the age of the universe, stars growing more metallic as they form starting with elements that can only be made by others going supernova, and chances of the planet not being hit by a supernova strong enough to sterilize the planet for billions of years. The great filter isn't necessarily still yet to come.
dekhn 4y ago
As for amino acids, I would just work on the assumption that they, and nucleosides, sort of people out of space organic chemistry on a regular basis, in a way that has nothing to do with life, but just basic chemistry/physics.
bmitc 4y ago
What observation methods would one use to detect life on Earth from even a moderate distance away? It is not known to me that we have the capability to even discover life on Earth if we were in another planet in another system. As far as I understand, exoplanet discovery and study is still incredibly rudimentary.
- cletus 4y ago
  SETI began by looking for radio signals that were highly unlikely to be "random" because that fit what we ourselves were using at the time. As we've since discovered, this sort of communication was shortlived lasting just decades. So what could we observe instead? The answer is Dyson Swarms. These aren't rigid spheres as some seem to think (the original term was "Dyson Sphere" but is largely abandoned because of the confusion). It's merely a collection of orbitals to consume all the energy a star produces. Many (myself included) think this is the inevitable direction of our species. The only way to get rid of heat in space is to radiate it away. The frequency of the light emitted depends entirely on the temperature of the radiating object. This means a full Dyson Swarm would have a huge infrared signature. That sort of thing we could detect from a very far distance. A whole galaxy of these would be detectable from millions of light years away.
  - bmitc 4y ago
    I wasn't necessarily trying to address what we can look for. I was trying to ask, what are things we are even capable of looking for? I am aware of Dyson swarms, but is it not the case that the enumeration of objects that emit infrared large? The Fermi paradox is not really a paradox of sorts, especially given when it was formulated. Because if we aren't even capable of detecting life, then how can we ask where is it?
    - cletus 4y ago
      The Fermi Paradox isn't a paradox to many (including, I believe, Fermi). The answer many suspect (myself included) is that spacefaring life is incredibly rare so it's not really a "paradox" because there is nothing to detect.
gibolt 4y ago
Lots of child comments have made statements about what life 'needs' and why that would make things difficult. We don't know what conditions life 'needs' since we only have a sample size of 1. We can speculate, but nothing yet is a known fact.
- stormfather 4y ago
  Right. It's not like we would theorize the existence of biological life on earth from first principles if we didn't know about it beforehand. It's such a magical, complex thing. We have no idea what other kinds of incomprehensibly complicated reactions might occur.
BurningFrog 4y ago
Robin Hanson, who coined the term "Great Filter", presented a theory in 2021 to explain the Fermi Paradox. It's known as the "Grabby Aliens Theory". This 12 minute video does a good job of explaining the fairly non intuitive reasoning: https://www.youtube.com/watch?v=l3whaviTqqg https://www.youtube.com/watch?v=l3whaviTqqg As I understand it (it's not an easy theory to wrap your - or at least my - mind around), the reason we don't see any other civilizations is that we're among the first ones. This seems very unlikely, but is actually not. Because a successful hi tech civilization would likely be inclined to expand ("be grabby") and fill up the galaxy in ~100 million years, as Fermi pointed out. That would mean all habitable planets would then be taken, and no more civilizations would rise up from primordial goo like ours. That means - and it's a weird mental leap, but I think it's correct - that almost all civilizations arising "naturally" would have the same experience we have: The universe seems weirdly empty. I guess it also means that the galaxy is ours for the taking!
- kabdib 4y ago
  If we're the forerunners, it's our responsibility to leave behind huge and mysterious artifacts containing the secrets of the universe, filled with traps for the unwary. "Figby, get those doom-chompers synchronized with the shooting flames!" "Yes sir!" "And think of something more profound than 'Be nice to other beings and remember to call your mother(s)' for that final secret. Maybe get someone in the art department to help out." It's not easy being the Elder Race, but someone has to do it.
- cletus 4y ago
  That's not that new an idea. Even at 1% of c we could fully colonize the Milky Way in 10 million years, which is a blink of an eye compared to the >4B years the EArth has been here. The second issue is that planets don't really matter other than being essentially "mass repositories". They're a highly inefficient way of creating living area. I'm speaking of course of Dyson Swarms as a highly likely alternative. I saw "highly likely" because it requires no new physics, no new materials beyond what we already have, is orders of magnitude more efficient (in living space per unit mass terms) and is essentially just an engineering problem (obviously a big one). If you accept that premise then it's even less likely there are other spacefaring civilizations within our light cone because they would stick out like a sore thumb. Certainly a whole galaxy of these would be detectable by us currently from millions of light years away.
belter 4y ago
The most likely reason is the one show in the simulation made in this paper, I recently posted here. "Possible CETIs Within Our Galaxy and Communication Probability Among CETIs ": https://news.ycombinator.com/item?id=31449404 https://news.ycombinator.com/item?id=31449404" "...human beings need to survive 50 (+250 -49) Myr to receive one signal from other CETIs. Our results may quantitatively explain why we have not detected any alien signals so far. The uncertainty of the results has been discussed in detail and would be alleviated with the further improvement of our astronomical observation ability in the future..." The universe is a big, big place and civilizations come and go. We would need to be around for 50 million years, to have a good chance to catch a window that would match another civilization. We are barely around as a species for 2 million years and civilization is maybe 10,000 years old...
- marklubi 4y ago
  I've always held the belief that given the vastness of space, and the age of time, it's not just a question of if other intelligent life can exist, but whether or not we we will be in the same place at the same time.
  - zinclozenge 4y ago
    What if the probability of life forming on any given planet was so infinitesimally tiny that it happening on earth is already a fluke?
    - marklubi 4y ago
      I would think that it's shortsighted. Just on Earth, we've been through several millions of years of various evolutions. We've had fauna, mega fauna, mega flora, dinosaurs, so many things have occurred over millions of years. It's hard to believe that none of this has possibly occurred elsewhere. Edit: for clarity
      - zinclozenge 4y ago
        You're talking about evolution, I'm talking about life forming. More specifically, think about the likelihood of a cell forming from purely chemical reactions and kinetics.
stormfather 4y ago
The flaw in our approach to the Fermi paradox is that we are looking for intelligent life which resembles us as we are now. Big, corporal bodies made of proteins communicating with big, inefficient, slow frequency vibrations. But this is just a transitory phase in our evolution which will pass in the astronomical blink of an eye. Consider if you agree with these propositions: - Consciousness is an emergent property of computation - Computation is possible in any media - Computation is more efficient in smaller, less massy media - We are already beginning to fiddle with our own brains and this will accelerate - Our bodies in general have huge room for optimization and eventually will be completely unrecognizable or even unnecessary as we currently imagine them - Progress is exponential as our population grows in education, size and free time If these are true, what does that mean for our destiny as a species in 100k years? 1M years? I think we can all agree we will become cyborgs, but I think we still imagine our bodies having the same form factor. But that's the flawed assumption. Really we will shrink down. And what's the limit to how far down we shrink and how efficient and massless our bodies/brains get? How would we even be communicating in 1M years? Through entangled qubits? Vibrations in subspace? Who knows, but it's probably not something 21st century earth would even notice with a radio telescope. So the answer to the Fermi paradox isn't that intelligent life snuffs itself out after a few million years. That's terribly unimaginative. The answer is that from our perspective intelligent civilizations disappear because they change themselves so radically that they transcend our concept of what to look for.
- mentos 4y ago
  I imagine civilization will just be a solar powered server box floating through space running unreal engine 6.0x10^27
  - stormfather 4y ago
    inshallah
- blizdiddy 4y ago
  > I think we can all agree we will become cyborgs, Well, obviously! Who could imagine any other scenarios?! My mom just called me asking if i could replace her right foot with a hoverboard. I cant wait until I can no longer feel sunshine or grass. Living forever as a process in a virtual machine... my ancestors could have never dreamt of having such fulfillment.
throwawaycities 4y ago
> A core idea of this is that there are various filters that separate a new planet from one hosting spacefaring life. The most obvious, but least talked about filter is time. Let’s assume there is a civilization just like us on the other end of the Milky Way galaxy, it’s not like we can just “look out” and observe them. Assuming they blasted out radio signals, those radio signals would have to have been sent 100,000 years ago for us to detect them today. Alternatively for that same civilization to detect our earliest radio signals it take another 999,900 years. If this technologically advanced civilization was in the closest galaxy instead of the opposite end of the Milky Way, then our ability to detect one another’s signals traveling at the speed of light would be separated by over 2.5M years.
- messe 4y ago
  > The most obvious, but least talked about filter is time. For good reason: there's been a lot of it so far. Even at slower than light speeds, it would be possible for a sufficiently advanced civilization to send probes to ever star in the galaxy (or even colonize it) in just a few million years. So why don't we see any evidence of any prior civilization having done that? It would only take one.
  - pjmlp 4y ago
    Cough, Egyptian pyramids, jump doors with runes,... :) Now seriously, maybe we have and they just weren't interested.
  - cloverich 4y ago
    How long would they have to last though? We don't just have to both be advanced but also overlap in time. When you consider there are hundred million+ years between advanced life forms and intelligent life, and even millions of years between humans and intelligent humans, any signals of any kind may have to last for millions of years or more to be detected. Then there's so much space, so it probably takes more than one. Perhaps a million+ more than one. Then the final but to me most important thing, is we often assume advanced life looks like us. I personally believe it generally does -- for a bit. But if we're just a stepping stone to AI and then (perhaps) we disappear, advanced life forms like us only exist for a blip anyways. We probably don't even know what to look for. The possibilities are fascinating and humbling.
beej71 4y ago
One thing that always struck me about humanlike intelligence on Earth is how quickly it came about. The dinosaurs had 180 million years or so to get it right, and we find no evidence of so much as a simple tool. Were they no smarter that crows? All that time? And Homo has been around, what, 2 million years? In just 2 million years we've gone from basically zero tech to outer-freakin-space. Arguably, we've gone from nothing to outer-freakin-space in the last 6000 years, starting around the Bronze Age. That's astoundingly quick given how long life has existed on Earth. So it seems like as the dice were being thrown around we were just waiting for that magic run of all sixes that enabled us to, in the blink of an eye, become spacefaring. What was it? (Opposable thumbs? Language? War? Big brains? Etc?) And how likely are these things to happen in a magical combination? It took its sweet time here. Did we get lucky it only took 4 billion years? Or unlucky it took that long at all? But it never happened to the hapless dinos. Which is too bad, because space dinosaurs would be _awesome_. [Meme of dinosaurs looking up at the asteroid falling from the sky and one saying, "Oh fuck! The economy!"]
- vorpalhex 4y ago
  > What was it? My lacking-evidence and very unverified theory is that it's something like bicameral mind theory. It wasn't until we developed a complex enough brain to have self metacognition that we started to take off as a species.
  - everdrive 4y ago
    My lacking-evidence theory is that this primarily evolved in mammals due to the requirements of child care imposed by mammalian birth.
- skykooler 4y ago
  Maybe intelligent dinosaurs had a very strong "no littering" policy.
  - alchemist1e9 4y ago
    Silurian hypothesis is very intriguing. https://en.wikipedia.org/wiki/Silurian_hypothesis https://en.wikipedia.org/wiki/Silurian_hypothesis
edgyquant 4y ago
The Fermi paradox is a joke (literally.) It’s not meant to be taken seriously as science but as proof our understanding, specifically irt how we got complex life, is flawed. I really hate that there are entire media spheres dedicated to philosophizing about it. It also does little but derail every conversation about life in the universe into speculative science fiction.
rococode 4y ago
Anyone interested in this topic should check out Stephen Webb's book, "If the Universe Is Teeming with Aliens ... Where Is Everybody?". It's not perfect, but it goes over a lot of possible explanations (75 different explanations!) for the Fermi Paradox. It covers pretty much every theory I've seen when people discuss the topic, aside from a government cover-up haha. Simulations, aliens hiding on Earth, von Neumann probes, signals that we don't understand, distances being insurmountable, self-destructiveness, inescapable planets, singularities, it's got it all! A lot of the explanations ultimately can't get over the "OK, but surely there are at least a few exceptions" problem, but it's very fun to think about nonetheless. A really engrossing read if you like thinking about this stuff! https://www.goodreads.com/en/book/show/180506.If_the_Universe_Is_Teeming_with_Aliens_Where_Is_Everybody_ https://www.goodreads.com/en/book/show/180506.If_the_Univers...
tediousdemise 4y ago
The universe is infinite and continuously expanding. This cosmological scale, the monumental distance between celestial objects in deep space, would make it quite literally impossible for any extraterrestrial to feasibly be aware of or make contact with humans and vice versa. Even if we could travel beyond the speed of light, we'd still probably never make contact; there would be too many things that could go wrong. It's depressing to think about. Space limits everything, and is the simplest solution to the Fermi paradox (following Occam's razor). Source: I am a software engineer who works on cool space stuff
lm28469 4y ago
> we've had billions of years. Why aren't ther emore signs of technological life? I think the "billions of years" part is key. Humanity might die in the next centuries, or at least stop progressing technologically due to our lack of sustainable planning. If a human like life existed 100m years ago in a nearby planet we wouldn't now even if we sent basic probes, you'd need to dig just like we need to dig to find dino bones. Modern civilisation are maybe 5000-7000 years old, that's not even a blip in the universe history. The universe could develop millions of technologically advanced civilisations on different planets with no time overlap I also feel like lots of people are too much into sci fi, nothing guarantees technological progress can go much further than what we have and allow for large scale space exploration. We might not see signs of technological life because the most advanced thing they came up with are a few probes and some radio signals sent from so far away that you statistically will not find even if you look for them. The universe physical and time scale raise the fermi paradox, but the same physical and time scale give you an answer as to why we might not be able detect life
- mateo1 4y ago
  Lately I've been thinking that perhaps our technological progress might be deterministically leading us to our own destruction (or a major and irrecoverable regression) through some kind of unavoidable dynamic evolving. Like a combination of nuclear weapons, biotechnology or AI with a tragedy of the commons type situation derived from the same competitive social nature that is required for us (or any other society) to develop technologically. Perhaps even the most basic property of life, the self-preserving tendency of a self-preserving structure once it randomly emerges, can lead with mathematical precision to its own destruction a few billion years later, regardless of the specifics and despite the profoundly complex mechanisms evolved in-between. Perhaps long-lived advanced civilizations are not possible at all, and can be seen as a weird transient natural phenomenon; starting with hydrothermal vents and ending with billions of odd etched silicon fossils.

by cletus 4y ago

JumpCrisscross 4y ago

> more species are likely getting filtered further down the chain My personal hunch is the filter is around multicellular life. We'll find lots of planets with single-celled goop. Many fewer with animals. The unions that created photosynthesis and mitochondria look to have happened only once (successfully) in Earth's history [1], and sound more like voodoo than science the more one thinks about it. (Cell ate another cell then changed its mind and adopted it for 1.45 billion years.) [1] https://www.nature.com/scitable/topicpage/the-origin-of-mitochondria-14232356/ https://www.nature.com/scitable/topicpage/the-origin-of-mito...

cletus 4y ago
The earliest signs of life at >3.5B years old [1] while photosynthesis dates to ~3.4B years ago. That seems to be pretty quick (by some definition, ~100 million years with huge error bars is "quick"). If photosynthesis only evolved once, another explanation is that it only needed to once because it was so wildly successful. Multicellular is interesting. That obviously took much longer but once it did? Holy crap did things take off. I kinda wish I could have a time machine just to visit the Cambrian Explosion era. [1]: https://en.wikipedia.org/wiki/Evolution_of_photosynthesis https://en.wikipedia.org/wiki/Evolution_of_photosynthesis

lumost 4y ago

While we're speculating, allow me to throw my 2 cents in. The biochemistry of life is likely to be common, the conditions for complex or even intelligent tool using life are likely to be rare. To have an earth, you need to have a moon comparable in mass to the planet to avoid atmospheric stripping. A temperature regime stable enough to support long term life development between 0 and 100 C. A star that doesn't blasttge planet in radiation every few thousand years. Along with a reasonable balance of materials, and a stellar neighborhood which wont swing the balance too badly every few million years. Lastly, although untested, To have tool use, you likely need a planet with gravity thats strong enough for the atmosphere to be stable, but weak enough for organic molecules to hold together complex life and enable the construction of material objects. A super earth covered in algae is interesting, but may not be capable of traditional human intelligence.

EForEndeavour 4y ago
> To have an earth, you need to have a moon comparable in mass to the planet to avoid atmospheric stripping. Could you elaborate on this? I'm aware that magnetospheres protect atmospheres from solar wind stripping (e.g., https://science.nasa.gov/science-news/news-articles/earths-magnetosphere https://science.nasa.gov/science-news/news-articles/earths-m...), but have never heard of the role of moons, and can't find anything via Google right now.
pasabagi 4y ago
My preferred speculation is simply that faster-than-light travel is impossible, so all the tool-using aliens out there are not visiting us because they can't, and we can't hear their signals because it gets lost against the background noise. I mean, would we be able to detect our own civilization from a few lightyears out? Apparently, unless you're pointing a radio telescope right at something, you woudn't be able to pick up human civilization levels of radio from more than a lightyear out. Say there's one smart tool-using civilization per 5000 lightyear volume, then they're unlikely to meet.
- spfzero 4y ago
  Even if a civilization out there had faster-than-light travel, they would most likely not know we were here. They would need to decide to come explore near us, probably need to expensively slow down to sub-light speeds to look for signs of life near here and pick up our emissions on some old archaic piece of equipment they happened to bring along. Would a much more advanced civilization spend their exploration budget to look over uninteresting primitives like us, or would they go off in search of other more advanced civilizations like their own?

hnuser123456 4y ago

Consider factors like the age of the universe, stars growing more metallic as they form starting with elements that can only be made by others going supernova, and chances of the planet not being hit by a supernova strong enough to sterilize the planet for billions of years. The great filter isn't necessarily still yet to come.

dekhn 4y ago

As for amino acids, I would just work on the assumption that they, and nucleosides, sort of people out of space organic chemistry on a regular basis, in a way that has nothing to do with life, but just basic chemistry/physics.

bmitc 4y ago

What observation methods would one use to detect life on Earth from even a moderate distance away? It is not known to me that we have the capability to even discover life on Earth if we were in another planet in another system. As far as I understand, exoplanet discovery and study is still incredibly rudimentary.

cletus 4y ago
SETI began by looking for radio signals that were highly unlikely to be "random" because that fit what we ourselves were using at the time. As we've since discovered, this sort of communication was shortlived lasting just decades. So what could we observe instead? The answer is Dyson Swarms. These aren't rigid spheres as some seem to think (the original term was "Dyson Sphere" but is largely abandoned because of the confusion). It's merely a collection of orbitals to consume all the energy a star produces. Many (myself included) think this is the inevitable direction of our species. The only way to get rid of heat in space is to radiate it away. The frequency of the light emitted depends entirely on the temperature of the radiating object. This means a full Dyson Swarm would have a huge infrared signature. That sort of thing we could detect from a very far distance. A whole galaxy of these would be detectable from millions of light years away.
- bmitc 4y ago
  I wasn't necessarily trying to address what we can look for. I was trying to ask, what are things we are even capable of looking for? I am aware of Dyson swarms, but is it not the case that the enumeration of objects that emit infrared large? The Fermi paradox is not really a paradox of sorts, especially given when it was formulated. Because if we aren't even capable of detecting life, then how can we ask where is it?
  - cletus 4y ago
    The Fermi Paradox isn't a paradox to many (including, I believe, Fermi). The answer many suspect (myself included) is that spacefaring life is incredibly rare so it's not really a "paradox" because there is nothing to detect.

gibolt 4y ago

Lots of child comments have made statements about what life 'needs' and why that would make things difficult. We don't know what conditions life 'needs' since we only have a sample size of 1. We can speculate, but nothing yet is a known fact.

stormfather 4y ago
Right. It's not like we would theorize the existence of biological life on earth from first principles if we didn't know about it beforehand. It's such a magical, complex thing. We have no idea what other kinds of incomprehensibly complicated reactions might occur.

BurningFrog 4y ago

Robin Hanson, who coined the term "Great Filter", presented a theory in 2021 to explain the Fermi Paradox. It's known as the "Grabby Aliens Theory". This 12 minute video does a good job of explaining the fairly non intuitive reasoning: https://www.youtube.com/watch?v=l3whaviTqqg https://www.youtube.com/watch?v=l3whaviTqqg As I understand it (it's not an easy theory to wrap your - or at least my - mind around), the reason we don't see any other civilizations is that we're among the first ones. This seems very unlikely, but is actually not. Because a successful hi tech civilization would likely be inclined to expand ("be grabby") and fill up the galaxy in ~100 million years, as Fermi pointed out. That would mean all habitable planets would then be taken, and no more civilizations would rise up from primordial goo like ours. That means - and it's a weird mental leap, but I think it's correct - that almost all civilizations arising "naturally" would have the same experience we have: The universe seems weirdly empty. I guess it also means that the galaxy is ours for the taking!

kabdib 4y ago
If we're the forerunners, it's our responsibility to leave behind huge and mysterious artifacts containing the secrets of the universe, filled with traps for the unwary. "Figby, get those doom-chompers synchronized with the shooting flames!" "Yes sir!" "And think of something more profound than 'Be nice to other beings and remember to call your mother(s)' for that final secret. Maybe get someone in the art department to help out." It's not easy being the Elder Race, but someone has to do it.
cletus 4y ago
That's not that new an idea. Even at 1% of c we could fully colonize the Milky Way in 10 million years, which is a blink of an eye compared to the >4B years the EArth has been here. The second issue is that planets don't really matter other than being essentially "mass repositories". They're a highly inefficient way of creating living area. I'm speaking of course of Dyson Swarms as a highly likely alternative. I saw "highly likely" because it requires no new physics, no new materials beyond what we already have, is orders of magnitude more efficient (in living space per unit mass terms) and is essentially just an engineering problem (obviously a big one). If you accept that premise then it's even less likely there are other spacefaring civilizations within our light cone because they would stick out like a sore thumb. Certainly a whole galaxy of these would be detectable by us currently from millions of light years away.

belter 4y ago

The most likely reason is the one show in the simulation made in this paper, I recently posted here. "Possible CETIs Within Our Galaxy and Communication Probability Among CETIs ": https://news.ycombinator.com/item?id=31449404 https://news.ycombinator.com/item?id=31449404" "...human beings need to survive 50 (+250 -49) Myr to receive one signal from other CETIs. Our results may quantitatively explain why we have not detected any alien signals so far. The uncertainty of the results has been discussed in detail and would be alleviated with the further improvement of our astronomical observation ability in the future..." The universe is a big, big place and civilizations come and go. We would need to be around for 50 million years, to have a good chance to catch a window that would match another civilization. We are barely around as a species for 2 million years and civilization is maybe 10,000 years old...

marklubi 4y ago
I've always held the belief that given the vastness of space, and the age of time, it's not just a question of if other intelligent life can exist, but whether or not we we will be in the same place at the same time.
- zinclozenge 4y ago
  What if the probability of life forming on any given planet was so infinitesimally tiny that it happening on earth is already a fluke?
  - marklubi 4y ago
    I would think that it's shortsighted. Just on Earth, we've been through several millions of years of various evolutions. We've had fauna, mega fauna, mega flora, dinosaurs, so many things have occurred over millions of years. It's hard to believe that none of this has possibly occurred elsewhere. Edit: for clarity
    - zinclozenge 4y ago
      You're talking about evolution, I'm talking about life forming. More specifically, think about the likelihood of a cell forming from purely chemical reactions and kinetics.

stormfather 4y ago

The flaw in our approach to the Fermi paradox is that we are looking for intelligent life which resembles us as we are now. Big, corporal bodies made of proteins communicating with big, inefficient, slow frequency vibrations. But this is just a transitory phase in our evolution which will pass in the astronomical blink of an eye. Consider if you agree with these propositions: - Consciousness is an emergent property of computation - Computation is possible in any media - Computation is more efficient in smaller, less massy media - We are already beginning to fiddle with our own brains and this will accelerate - Our bodies in general have huge room for optimization and eventually will be completely unrecognizable or even unnecessary as we currently imagine them - Progress is exponential as our population grows in education, size and free time If these are true, what does that mean for our destiny as a species in 100k years? 1M years? I think we can all agree we will become cyborgs, but I think we still imagine our bodies having the same form factor. But that's the flawed assumption. Really we will shrink down. And what's the limit to how far down we shrink and how efficient and massless our bodies/brains get? How would we even be communicating in 1M years? Through entangled qubits? Vibrations in subspace? Who knows, but it's probably not something 21st century earth would even notice with a radio telescope. So the answer to the Fermi paradox isn't that intelligent life snuffs itself out after a few million years. That's terribly unimaginative. The answer is that from our perspective intelligent civilizations disappear because they change themselves so radically that they transcend our concept of what to look for.

mentos 4y ago
I imagine civilization will just be a solar powered server box floating through space running unreal engine 6.0x10^27
- stormfather 4y ago
  inshallah
blizdiddy 4y ago
> I think we can all agree we will become cyborgs, Well, obviously! Who could imagine any other scenarios?! My mom just called me asking if i could replace her right foot with a hoverboard. I cant wait until I can no longer feel sunshine or grass. Living forever as a process in a virtual machine... my ancestors could have never dreamt of having such fulfillment.

throwawaycities 4y ago

> A core idea of this is that there are various filters that separate a new planet from one hosting spacefaring life. The most obvious, but least talked about filter is time. Let’s assume there is a civilization just like us on the other end of the Milky Way galaxy, it’s not like we can just “look out” and observe them. Assuming they blasted out radio signals, those radio signals would have to have been sent 100,000 years ago for us to detect them today. Alternatively for that same civilization to detect our earliest radio signals it take another 999,900 years. If this technologically advanced civilization was in the closest galaxy instead of the opposite end of the Milky Way, then our ability to detect one another’s signals traveling at the speed of light would be separated by over 2.5M years.

messe 4y ago
> The most obvious, but least talked about filter is time. For good reason: there's been a lot of it so far. Even at slower than light speeds, it would be possible for a sufficiently advanced civilization to send probes to ever star in the galaxy (or even colonize it) in just a few million years. So why don't we see any evidence of any prior civilization having done that? It would only take one.
- pjmlp 4y ago
  Cough, Egyptian pyramids, jump doors with runes,... :) Now seriously, maybe we have and they just weren't interested.
- cloverich 4y ago
  How long would they have to last though? We don't just have to both be advanced but also overlap in time. When you consider there are hundred million+ years between advanced life forms and intelligent life, and even millions of years between humans and intelligent humans, any signals of any kind may have to last for millions of years or more to be detected. Then there's so much space, so it probably takes more than one. Perhaps a million+ more than one. Then the final but to me most important thing, is we often assume advanced life looks like us. I personally believe it generally does -- for a bit. But if we're just a stepping stone to AI and then (perhaps) we disappear, advanced life forms like us only exist for a blip anyways. We probably don't even know what to look for. The possibilities are fascinating and humbling.

beej71 4y ago

One thing that always struck me about humanlike intelligence on Earth is how quickly it came about. The dinosaurs had 180 million years or so to get it right, and we find no evidence of so much as a simple tool. Were they no smarter that crows? All that time? And Homo has been around, what, 2 million years? In just 2 million years we've gone from basically zero tech to outer-freakin-space. Arguably, we've gone from nothing to outer-freakin-space in the last 6000 years, starting around the Bronze Age. That's astoundingly quick given how long life has existed on Earth. So it seems like as the dice were being thrown around we were just waiting for that magic run of all sixes that enabled us to, in the blink of an eye, become spacefaring. What was it? (Opposable thumbs? Language? War? Big brains? Etc?) And how likely are these things to happen in a magical combination? It took its sweet time here. Did we get lucky it only took 4 billion years? Or unlucky it took that long at all? But it never happened to the hapless dinos. Which is too bad, because space dinosaurs would be _awesome_. [Meme of dinosaurs looking up at the asteroid falling from the sky and one saying, "Oh fuck! The economy!"]

vorpalhex 4y ago
> What was it? My lacking-evidence and very unverified theory is that it's something like bicameral mind theory. It wasn't until we developed a complex enough brain to have self metacognition that we started to take off as a species.
- everdrive 4y ago
  My lacking-evidence theory is that this primarily evolved in mammals due to the requirements of child care imposed by mammalian birth.
skykooler 4y ago
Maybe intelligent dinosaurs had a very strong "no littering" policy.
- alchemist1e9 4y ago
  Silurian hypothesis is very intriguing. https://en.wikipedia.org/wiki/Silurian_hypothesis https://en.wikipedia.org/wiki/Silurian_hypothesis

edgyquant 4y ago

The Fermi paradox is a joke (literally.) It’s not meant to be taken seriously as science but as proof our understanding, specifically irt how we got complex life, is flawed. I really hate that there are entire media spheres dedicated to philosophizing about it. It also does little but derail every conversation about life in the universe into speculative science fiction.

rococode 4y ago

Anyone interested in this topic should check out Stephen Webb's book, "If the Universe Is Teeming with Aliens ... Where Is Everybody?". It's not perfect, but it goes over a lot of possible explanations (75 different explanations!) for the Fermi Paradox. It covers pretty much every theory I've seen when people discuss the topic, aside from a government cover-up haha. Simulations, aliens hiding on Earth, von Neumann probes, signals that we don't understand, distances being insurmountable, self-destructiveness, inescapable planets, singularities, it's got it all! A lot of the explanations ultimately can't get over the "OK, but surely there are at least a few exceptions" problem, but it's very fun to think about nonetheless. A really engrossing read if you like thinking about this stuff! https://www.goodreads.com/en/book/show/180506.If_the_Universe_Is_Teeming_with_Aliens_Where_Is_Everybody_ https://www.goodreads.com/en/book/show/180506.If_the_Univers...

tediousdemise 4y ago

The universe is infinite and continuously expanding. This cosmological scale, the monumental distance between celestial objects in deep space, would make it quite literally impossible for any extraterrestrial to feasibly be aware of or make contact with humans and vice versa. Even if we could travel beyond the speed of light, we'd still probably never make contact; there would be too many things that could go wrong. It's depressing to think about. Space limits everything, and is the simplest solution to the Fermi paradox (following Occam's razor). Source: I am a software engineer who works on cool space stuff

lm28469 4y ago

> we've had billions of years. Why aren't ther emore signs of technological life? I think the "billions of years" part is key. Humanity might die in the next centuries, or at least stop progressing technologically due to our lack of sustainable planning. If a human like life existed 100m years ago in a nearby planet we wouldn't now even if we sent basic probes, you'd need to dig just like we need to dig to find dino bones. Modern civilisation are maybe 5000-7000 years old, that's not even a blip in the universe history. The universe could develop millions of technologically advanced civilisations on different planets with no time overlap I also feel like lots of people are too much into sci fi, nothing guarantees technological progress can go much further than what we have and allow for large scale space exploration. We might not see signs of technological life because the most advanced thing they came up with are a few probes and some radio signals sent from so far away that you statistically will not find even if you look for them. The universe physical and time scale raise the fermi paradox, but the same physical and time scale give you an answer as to why we might not be able detect life

mateo1 4y ago
Lately I've been thinking that perhaps our technological progress might be deterministically leading us to our own destruction (or a major and irrecoverable regression) through some kind of unavoidable dynamic evolving. Like a combination of nuclear weapons, biotechnology or AI with a tragedy of the commons type situation derived from the same competitive social nature that is required for us (or any other society) to develop technologically. Perhaps even the most basic property of life, the self-preserving tendency of a self-preserving structure once it randomly emerges, can lead with mathematical precision to its own destruction a few billion years later, regardless of the specifics and despite the profoundly complex mechanisms evolved in-between. Perhaps long-lived advanced civilizations are not possible at all, and can be seen as a weird transient natural phenomenon; starting with hydrothermal vents and ending with billions of odd etched silicon fossils.