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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 interst

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 2y ago
Even in this scenario I would still expect to see Von Neumann machines at some point.
- palata 2y 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 2y 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 2y 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 2y 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 2y 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 2y ago
      Very little to no evidence that AI is a “binary outcome”.
      - richardw 2y ago
        Very little to no evidence that continuously increasing intelligence will maintain the status quo indefinitely, on a scale of at least thousands of years. The odds of us not either populating the galaxy or utterly owning ourselves are vanishingly small. What is the middle ground that you think is likely, and what things have to happen for that to be true? Why is it more likely than one of the extremes? It's so interesting that our intuitions are vastly different on this. You and I both just can't believe that our default case isn't obvious. I personally think "recency bias" is to blame for the "we'll muddle through" case. Life is great and the weather is fine, and there are no asteroids or globally impacting volcanoes, and we haven't had a civilisational collapse in a good while, and nukes didn't kill us, so the current state is pretty locked in indefinitely, despite massive technological change that we have zero chance of predicting the outcomes of. That's an unstable equilibrium at best. We take over the galaxy or die trying.
- MrJohz 2y ago
  The Kurzgesagt videos on these sorts of topics are interesting and entertaining, but they're often very speculative — they can rely heavily on unique but unproven theories, unprovable philosophical questions, or even just interesting sci-fi premises. They're definitely informative and interesting within a given scope of discussion — it's good to ask interesting questions and explore what different answers might look like, because it helps us to push the boundaries of our mental models of the universe. But some of the videos — particularly the ones on Boltzmann brains or solutions to the Fermi paradox — are a lot closer to "here's an interesting thought experiment" than "here's something that's likely to be the case in our universe". (Although they're usually very explicit when they do dive into this sort of speculative territory, and they also do a lot of videos which aren't in this vein at all — this is no slight on Kurzgesagt and the people who enjoy watching them!)
  - cyberlurker 2y ago
    We’re essentially talking about the Fermi paradox. I think speculation is expected and the channel is upfront about their cited research. Your comment could apply to any one commenting on these topics and so I am confused.
    - MrJohz 2y ago
      Yeah, I didn't want my comment to be a criticism of Kuzgesagt - like you say, they're usually very upfront when they do their more speculative videos. But I think sometimes people see the Kuzgesagt name and are like "oh, that's the informative science videos, this must be true", whereas a lot of the Fermi paradox stuff is closer to speculative fiction in nature than some of their other videos.
- gcanyon 2y ago
  Here's the Kurzgesagt video on moving the solar system through the galaxy: https://www.youtube.com/watch?v=v3y8AIEX_dU https://www.youtube.com/watch?v=v3y8AIEX_dU I've seen at least one "physicist reacts" video to this that tl;dw's to: "seems reasonable, would obviously require a lot of technological advancement and work"
- AtlasBarfed 2y ago
  Nah, we'll be fine, the 10% increase in brightness can be easily countered with space (or orbital) shields/solar power stations. If we don't have a very active interplanetary society in 100 million years we're almost certainly extinct.
pfdietz 2y ago
Neither FTL travel nor unitary interstellar civilizations are necessary for the Fermi argument to bite.
palata 2y 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 2y 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 2y 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 2y 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 2y 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.

fredsmith219 2y ago

Even in this scenario I would still expect to see Von Neumann machines at some point.

palata 2y 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 2y 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 2y 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 2y 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 2y 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 2y ago
    Very little to no evidence that AI is a “binary outcome”.
    - richardw 2y ago
      Very little to no evidence that continuously increasing intelligence will maintain the status quo indefinitely, on a scale of at least thousands of years. The odds of us not either populating the galaxy or utterly owning ourselves are vanishingly small. What is the middle ground that you think is likely, and what things have to happen for that to be true? Why is it more likely than one of the extremes? It's so interesting that our intuitions are vastly different on this. You and I both just can't believe that our default case isn't obvious. I personally think "recency bias" is to blame for the "we'll muddle through" case. Life is great and the weather is fine, and there are no asteroids or globally impacting volcanoes, and we haven't had a civilisational collapse in a good while, and nukes didn't kill us, so the current state is pretty locked in indefinitely, despite massive technological change that we have zero chance of predicting the outcomes of. That's an unstable equilibrium at best. We take over the galaxy or die trying.
MrJohz 2y ago
The Kurzgesagt videos on these sorts of topics are interesting and entertaining, but they're often very speculative — they can rely heavily on unique but unproven theories, unprovable philosophical questions, or even just interesting sci-fi premises. They're definitely informative and interesting within a given scope of discussion — it's good to ask interesting questions and explore what different answers might look like, because it helps us to push the boundaries of our mental models of the universe. But some of the videos — particularly the ones on Boltzmann brains or solutions to the Fermi paradox — are a lot closer to "here's an interesting thought experiment" than "here's something that's likely to be the case in our universe". (Although they're usually very explicit when they do dive into this sort of speculative territory, and they also do a lot of videos which aren't in this vein at all — this is no slight on Kurzgesagt and the people who enjoy watching them!)
- cyberlurker 2y ago
  We’re essentially talking about the Fermi paradox. I think speculation is expected and the channel is upfront about their cited research. Your comment could apply to any one commenting on these topics and so I am confused.
  - MrJohz 2y ago
    Yeah, I didn't want my comment to be a criticism of Kuzgesagt - like you say, they're usually very upfront when they do their more speculative videos. But I think sometimes people see the Kuzgesagt name and are like "oh, that's the informative science videos, this must be true", whereas a lot of the Fermi paradox stuff is closer to speculative fiction in nature than some of their other videos.
gcanyon 2y ago
Here's the Kurzgesagt video on moving the solar system through the galaxy: https://www.youtube.com/watch?v=v3y8AIEX_dU https://www.youtube.com/watch?v=v3y8AIEX_dU I've seen at least one "physicist reacts" video to this that tl;dw's to: "seems reasonable, would obviously require a lot of technological advancement and work"
AtlasBarfed 2y ago
Nah, we'll be fine, the 10% increase in brightness can be easily countered with space (or orbital) shields/solar power stations. If we don't have a very active interplanetary society in 100 million years we're almost certainly extinct.

pfdietz 2y ago

Neither FTL travel nor unitary interstellar civilizations are necessary for the Fermi argument to bite.

palata 2y 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 2y 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 2y 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 2y 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 2y 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.