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Let’s just hope it’s not the “dark forest” theory that’s correct, although it would make a lot of sense to me assuming the universe is teeming with life.

TomSwirly 3y ago
The most likely theory is that the universe is much like it appears to be and the speed of light is an absolute barrier, and that in practice means that interstellar civilizations never form, because it's simply far, far too expensive and difficult. If alien civilizations lasted indefinitely, that wouldn't be a barrier, but in the one sample of a civilization we have, we are consuming our resources and generating waste at an exponentially increasing rate, and will crash and burn leaving us without the quadrillions of "dollars" it would take to even start colonizing the stars.
- fredsmith219 3y ago
  Even in this scenario I would still expect to see Von Neumann machines at some point.
  - palata 3y ago
    You mean a civilization that can produce machines able to survive indefinitely in isolation, but that isn't capable of surviving itself? Doesn't sound particularly obvious to me...
- cyberlurker 3y ago
  Kurzgesagt has many videos on this topic. In one video, they point out we may actually be in the right place at the right time and could be one of the first civilizations. This seems egocentric at first, but if you consider how chaotic the early universe has been and how relatively calm things are in the last billion years, it does make sense. Also, I learned recently that we don’t have as much time with Earth as I originally thought. We have a few hundred million years to figure out how to colonize other planets or live in space before Earth becomes radically different and potentially unlivable. I imagine most civilizations get snuffed out like this.
  - pfdietz 3y ago
    The past survival of livable conditions on Earth is no guarantee they will persist for very long in the future. There's observer selection bias to consider. For example, the O2 level in the atmosphere could drop below that needed to sustain higher life. As I understand it, there's been no feedback mechanism identified that stabilizes O2 at current levels, so the persistence of adequate oxygen over the last 500 million years could just be an unlikely accident. In the absence of burial of photosynthesized materials atmospheric O2 will disappear in a few million years as reduced materials are exposed by geological processes and then oxidized. So, the time constant for O2 fluctuations is rather short. If and when we spread into the galaxy, we may find many planets where livable conditions were snuffed out before intelligence could arise. In our own solar system, both Mars and Venus may have been more habitable than Earth earlier in the history of the solar system, but now are forever ruined.
  - palata 3y ago
    > We have a few hundred million years to figure out how to colonize other planets or live in space before Earth becomes radically different and potentially unlivable. Hmm... at the rate we are going, big parts of the Earth (a big slice around the Equator) may well become unlivable for human beings in a couple of decades. I get the idea that it won't mean that the Earth will be unlivable for all organisms, but from what we know, a sufficiently advanced civilization only needs a couple hundred years to destroy itself.
    - richardw 3y ago
      And AI is likely a binary outcome. It’s either very good for us or not, and it won’t take a million years to figure out which. We were in caves not long ago.
      - bamboozled 3y ago
        Very little to no evidence that AI is a “binary outcome”.
        3y ago
- pfdietz 3y ago
  Neither FTL travel nor unitary interstellar civilizations are necessary for the Fermi argument to bite.
- palata 3y ago
  Not sure why you got downvoted :-/. I am always surprised by how people tend to completely ignore the scale of the universe. People get excited by claims to "go back to the Moon, then Mars, then who knows?", but the truth is that given our current understanding of the world, sending humans on another solar system is theoretically impossible. Just look at those distances: we just can't, period. Of course, we may discover new fundamental physics that would change that. But that's a fundamental problem, not an engineering problem. Instead of wasting money and energy on the engineering required to send humans to Mars (which is an artistic performance at this point), we should pay fundamental physicists to attempt to revolutionize our understanding of the world (wishing them luck) and spend those resources into something that is actually important for life: preserving life on Earth. Right now we as a civilization are failing to survive on Earth. It seems reasonable to consider that other civilizations may have the same problems.
  - nojs 3y ago
    It’s not theoretically impossible, it’s just really hard. If we go fast enough, we can even do it within the current lifespan of a human (from the perspective of that human). https://en.m.wikipedia.org/wiki/File:Roundtriptimes.png https://en.m.wikipedia.org/wiki/File:Roundtriptimes.png
    - palata 3y ago
      Well, it starts with "assuming we had something we don't have (i.e. the capability to accelerate at 1G for 100 years)"... I meant it's theoretically impossible with the theory that we have now. Of course if we make breakthroughs in the theory, then the theory will change and it may become possible. But SpaceX going to Mars is not exactly revisiting this theory. They are just having fun with the current state of the theory, which says that they won't bring humans further, period.
      - jonahrd 3y ago
        I don't mean to be nitpicky, but you specified the difference between a theoretical impossibility and an engineering impossibility in your parent comment. I assume the reply is just referring to the fact that technically getting to a star system within the 10s of light-years away is an engineering feat, not a break-the-known-rules-of-the-universe feat. I don't take it that they're actually claiming it's a realistic feat that may be accomplished soon.
- AtlasBarfed 3y ago
  If you have silicon/AI/computer-based intelligence, then it's a lot more durable in space and lasts a lot longer. That's a totally different ballgame. You don't even need habitable worlds, arguably what would be valuable is asteroids since you don't have gravity wells. 200 year transits isn't a big deal then. They could tolerate the G-forces of an Orion pulse nuclear ship a lot better too. That's 1960s tech, if you have some antimatter collectors in space (my idea for a starship-based startup, how valuable is antimatter?), then you get to have even more fun. Orion can do .1c with fission. One of the big problems was getting it off the ground and the fallout was unacceptable. BUT, with starship doing 150-250 tons, that means 8 flights for a 4,000 ton low-end orion, or ... a lot more for the high end 1,000,000 ton orion.
smallmancontrov 3y ago
Three Body Problem is a lot of fun, but if you are that concerned by it you should seek out the broader Fermi Paradox dialogue which does not favor this solution, and not just because it's unwanted. Isaac Arthur's Fermi Paradox Compendium on youtube is probably a good place to start and I'm pretty sure his Dark Forest video covers the major points. In any case, I have them here too: If the universe is teeming with alien life, why isn't it here? It looks like it will take millions of years to colonize the galaxy but the likely variation in emergence/evolutionary timelines is some decent fraction of billions of years (considerably more than 4 billion years, the starting gun is metallicity not the formation of Earth). In particular, if there is highly capable space-faring life at Alpha Centauri, why haven't they probed their neighboring star system in a billion years even though it was completely trivial to do so relative to subsequently displayed technological feats? Also: it's really hard to configure the rules of a Dark Forest so that the optimal strategy is "hide" rather than "grow, grow, grow -- and hope you grow fast enough by the time it matters," and it's spectacularly hard to make that so universal across all aliens that none of them "wins" and colonizes the galaxy per the previous paragraph. Finally, Cixin Liu had to break the speed of light to make his story work (and then carefully avoid the implications to #1 and #2 above, which both get worse if c is no longer a constraint). I am all for doing what it takes to tell the story, and even more delighted by his deeper exploration of this concept further down the line, but one must remember to adjust the likelihoods of it all according to the likelihood of the premise, which seems quite low according to our present understanding.
- pfdietz 3y ago
  This is a nit pick and doesn't change your argument, but Alpha Centauri would not have been our neighboring star system for a billion years. Stars move relative to each other in our stellar neighborhood at about 30 km/s, or one light year every 10,000 years.
  - smallmancontrov 3y ago
    Yep, good reminder! Of course, as you point out, it doesn't change the argument because probing (or simply direct observation, if they must hide) would still be trivial, both at larger distances when we weren't quite neighbors and on the shorter timescale when we were. Trivial next to mustering an interstellar invasion fleet on the turn of a dime, at any rate. Besides, if they were itching for a fight then the original "decent fraction of billions of years" timeline still applies to the question of "why didn't they grow and colonize?"
NegativeLatency 3y ago
Personally I would rather take the chance of being destroyed than destroy other life. That whole idea is also based on IMO the worst instincts of our race. For all we know making it past the great filter involves developing an increased empathy for all life.
- foobar1962 3y ago
  > Personally I would rather take the chance of being destroyed than destroy other life. Great. So don't wash your hands before eating... and don't eat.
- AtlasBarfed 3y ago
  It is based on instincts, which are tied to survival, which is inherent to biological competition, which is inherent to evolution. It is unlikely life elsewhere won't involve the same fundamental game theory.
lannisterstark 3y ago
Cixin straight up borrowed this from The Killing Star. You should read that. It's also pretty fun but goes 0-100 in chapter 1.

TomSwirly 3y ago

The most likely theory is that the universe is much like it appears to be and the speed of light is an absolute barrier, and that in practice means that interstellar civilizations never form, because it's simply far, far too expensive and difficult. If alien civilizations lasted indefinitely, that wouldn't be a barrier, but in the one sample of a civilization we have, we are consuming our resources and generating waste at an exponentially increasing rate, and will crash and burn leaving us without the quadrillions of "dollars" it would take to even start colonizing the stars.

fredsmith219 3y ago
Even in this scenario I would still expect to see Von Neumann machines at some point.
- palata 3y ago
  You mean a civilization that can produce machines able to survive indefinitely in isolation, but that isn't capable of surviving itself? Doesn't sound particularly obvious to me...
cyberlurker 3y ago
Kurzgesagt has many videos on this topic. In one video, they point out we may actually be in the right place at the right time and could be one of the first civilizations. This seems egocentric at first, but if you consider how chaotic the early universe has been and how relatively calm things are in the last billion years, it does make sense. Also, I learned recently that we don’t have as much time with Earth as I originally thought. We have a few hundred million years to figure out how to colonize other planets or live in space before Earth becomes radically different and potentially unlivable. I imagine most civilizations get snuffed out like this.
- pfdietz 3y ago
  The past survival of livable conditions on Earth is no guarantee they will persist for very long in the future. There's observer selection bias to consider. For example, the O2 level in the atmosphere could drop below that needed to sustain higher life. As I understand it, there's been no feedback mechanism identified that stabilizes O2 at current levels, so the persistence of adequate oxygen over the last 500 million years could just be an unlikely accident. In the absence of burial of photosynthesized materials atmospheric O2 will disappear in a few million years as reduced materials are exposed by geological processes and then oxidized. So, the time constant for O2 fluctuations is rather short. If and when we spread into the galaxy, we may find many planets where livable conditions were snuffed out before intelligence could arise. In our own solar system, both Mars and Venus may have been more habitable than Earth earlier in the history of the solar system, but now are forever ruined.
- palata 3y ago
  > We have a few hundred million years to figure out how to colonize other planets or live in space before Earth becomes radically different and potentially unlivable. Hmm... at the rate we are going, big parts of the Earth (a big slice around the Equator) may well become unlivable for human beings in a couple of decades. I get the idea that it won't mean that the Earth will be unlivable for all organisms, but from what we know, a sufficiently advanced civilization only needs a couple hundred years to destroy itself.
  - richardw 3y ago
    And AI is likely a binary outcome. It’s either very good for us or not, and it won’t take a million years to figure out which. We were in caves not long ago.
    - bamboozled 3y ago
      Very little to no evidence that AI is a “binary outcome”.
      - 3y ago
pfdietz 3y ago
Neither FTL travel nor unitary interstellar civilizations are necessary for the Fermi argument to bite.
palata 3y ago
Not sure why you got downvoted :-/. I am always surprised by how people tend to completely ignore the scale of the universe. People get excited by claims to "go back to the Moon, then Mars, then who knows?", but the truth is that given our current understanding of the world, sending humans on another solar system is theoretically impossible. Just look at those distances: we just can't, period. Of course, we may discover new fundamental physics that would change that. But that's a fundamental problem, not an engineering problem. Instead of wasting money and energy on the engineering required to send humans to Mars (which is an artistic performance at this point), we should pay fundamental physicists to attempt to revolutionize our understanding of the world (wishing them luck) and spend those resources into something that is actually important for life: preserving life on Earth. Right now we as a civilization are failing to survive on Earth. It seems reasonable to consider that other civilizations may have the same problems.
- nojs 3y ago
  It’s not theoretically impossible, it’s just really hard. If we go fast enough, we can even do it within the current lifespan of a human (from the perspective of that human). https://en.m.wikipedia.org/wiki/File:Roundtriptimes.png https://en.m.wikipedia.org/wiki/File:Roundtriptimes.png
  - palata 3y ago
    Well, it starts with "assuming we had something we don't have (i.e. the capability to accelerate at 1G for 100 years)"... I meant it's theoretically impossible with the theory that we have now. Of course if we make breakthroughs in the theory, then the theory will change and it may become possible. But SpaceX going to Mars is not exactly revisiting this theory. They are just having fun with the current state of the theory, which says that they won't bring humans further, period.
    - jonahrd 3y ago
      I don't mean to be nitpicky, but you specified the difference between a theoretical impossibility and an engineering impossibility in your parent comment. I assume the reply is just referring to the fact that technically getting to a star system within the 10s of light-years away is an engineering feat, not a break-the-known-rules-of-the-universe feat. I don't take it that they're actually claiming it's a realistic feat that may be accomplished soon.
AtlasBarfed 3y ago
If you have silicon/AI/computer-based intelligence, then it's a lot more durable in space and lasts a lot longer. That's a totally different ballgame. You don't even need habitable worlds, arguably what would be valuable is asteroids since you don't have gravity wells. 200 year transits isn't a big deal then. They could tolerate the G-forces of an Orion pulse nuclear ship a lot better too. That's 1960s tech, if you have some antimatter collectors in space (my idea for a starship-based startup, how valuable is antimatter?), then you get to have even more fun. Orion can do .1c with fission. One of the big problems was getting it off the ground and the fallout was unacceptable. BUT, with starship doing 150-250 tons, that means 8 flights for a 4,000 ton low-end orion, or ... a lot more for the high end 1,000,000 ton orion.

smallmancontrov 3y ago

Three Body Problem is a lot of fun, but if you are that concerned by it you should seek out the broader Fermi Paradox dialogue which does not favor this solution, and not just because it's unwanted. Isaac Arthur's Fermi Paradox Compendium on youtube is probably a good place to start and I'm pretty sure his Dark Forest video covers the major points. In any case, I have them here too: If the universe is teeming with alien life, why isn't it here? It looks like it will take millions of years to colonize the galaxy but the likely variation in emergence/evolutionary timelines is some decent fraction of billions of years (considerably more than 4 billion years, the starting gun is metallicity not the formation of Earth). In particular, if there is highly capable space-faring life at Alpha Centauri, why haven't they probed their neighboring star system in a billion years even though it was completely trivial to do so relative to subsequently displayed technological feats? Also: it's really hard to configure the rules of a Dark Forest so that the optimal strategy is "hide" rather than "grow, grow, grow -- and hope you grow fast enough by the time it matters," and it's spectacularly hard to make that so universal across all aliens that none of them "wins" and colonizes the galaxy per the previous paragraph. Finally, Cixin Liu had to break the speed of light to make his story work (and then carefully avoid the implications to #1 and #2 above, which both get worse if c is no longer a constraint). I am all for doing what it takes to tell the story, and even more delighted by his deeper exploration of this concept further down the line, but one must remember to adjust the likelihoods of it all according to the likelihood of the premise, which seems quite low according to our present understanding.

pfdietz 3y ago
This is a nit pick and doesn't change your argument, but Alpha Centauri would not have been our neighboring star system for a billion years. Stars move relative to each other in our stellar neighborhood at about 30 km/s, or one light year every 10,000 years.
- smallmancontrov 3y ago
  Yep, good reminder! Of course, as you point out, it doesn't change the argument because probing (or simply direct observation, if they must hide) would still be trivial, both at larger distances when we weren't quite neighbors and on the shorter timescale when we were. Trivial next to mustering an interstellar invasion fleet on the turn of a dime, at any rate. Besides, if they were itching for a fight then the original "decent fraction of billions of years" timeline still applies to the question of "why didn't they grow and colonize?"

NegativeLatency 3y ago

Personally I would rather take the chance of being destroyed than destroy other life. That whole idea is also based on IMO the worst instincts of our race. For all we know making it past the great filter involves developing an increased empathy for all life.

foobar1962 3y ago
> Personally I would rather take the chance of being destroyed than destroy other life. Great. So don't wash your hands before eating... and don't eat.
AtlasBarfed 3y ago
It is based on instincts, which are tied to survival, which is inherent to biological competition, which is inherent to evolution. It is unlikely life elsewhere won't involve the same fundamental game theory.

lannisterstark 3y ago

Cixin straight up borrowed this from The Killing Star. You should read that. It's also pretty fun but goes 0-100 in chapter 1.