5 ms·

If von Neuman probes are possible, and some percentage of civilizations create them, then at least von Neuman probes should be here. von Neuman probes solve th

by ericb 3y ago

If von Neuman probes are possible, and some percentage of civilizations create them, then at least von Neuman probes should be here. von Neuman probes solve the travel time, cost, and distance objections for ETI even if light speed is the absolute limit. https://en.wikipedia.org/wiki/Self-replicating_spacecraft https://en.wikipedia.org/wiki/Self-replicating_spacecraft

seventytwo 3y ago
Big “if”.
- ericb 3y ago
  Which one? They all seem more likely than not.
  - deleted 3y ago
    [deleted]
actionfromafar 3y ago
Why should they be here? That seems a stretch to me. We don't know the motivations by those who could send them.
- thriftwy 3y ago
  It makes sense to send them everywhere to have a sensor network wherever you go. The only reason why they may not be out there is because of Great Filter or because we are the first ones in our vicinity (would not be strange as our Universe is fairly young).
  - actionfromafar 3y ago
    Or they are scared of what they might find. Whenever I read "the only reason" I have doubts. How can we be so sure?
    - thriftwy 3y ago
      I wonder what you are having in mind regarding what they can find. Can an automated probe have a mental breakdown?
      - actionfromafar 3y ago
        I should have written "might encounter". What I'm getting at is that if someone sees your probe, you have now let on that you exist.
- ericb 3y ago
  We have observed exactly one sentient species, (ours) and it is sending probes already. There are 200 sextillion stars. For the opposite position (they shouldn't be here) to make sense, there has to be either no other civilizations, or our probe-sending habits are so rare that no other civilizations do it, or we are the first. Any of those other stances seem vastly more improbable, as they assume that our sample-of-one society just happens to be ludicrously different than all others.
  - actionfromafar 3y ago
    Since we have only a sample of one, I can never make my mind up on about what is probable or improbable. But I do believe it is technically possible in principle to construct and build von Neuman probes. Once they work inside a solar system, then work on making them withstand, say, a few million years in orbit and see if they still work, once they survive a few million years "inactive" (or constantly repairing themselves or whatever it takes), send them off to the stars. But it would take a patience and scale of industry we humans literally can only vaguely dream of.
    - ericb 3y ago
      > withstand, say, a few million years in orbit > ...scale of industry They don't have to do that. The probe just has to make more "child probes" before it dies. You don't need a huge industry if they are self-replicating. You need only one working probe to start, the rest handles itself.
      - actionfromafar 3y ago
        The "only" there does a lot of work. :-) And it has to survive for millions of years until it reaches a new solar system without something to "feed" on. In many ways it seems easier to make a Neuman probe which can survive within a solar system than something which can travel to another.
        gremlinsinc 3y ago
- Teever 3y ago
  We do know the motivations to some degree because they're constrained by physical reality, evolution, and game theory. Von Nuemann probes are possible in this physical reality for a relatively cheap cost and small time frame. It makes sense to put probes that can watch for threats anywhere you think that threats can be. Species that do this have a greater chance of survival than species that don't.
- gfodor 3y ago
  They should be here to ensure we don’t do anything that could hurt anyone not on Earth’s surface.
cratermoon 3y ago
Space is far, far larger than the mind can easily conceive. To "von Neuman probes should be here" is to fail to comprehend just how improbable it would be for a spacecraft to be aimed at Earth.
- ericb 3y ago
  You don't aim a von Neuman probe anywhere. You use unbounded exponential math to send them everywhere as they are free. It seems like you might find the idea interesting if you look into the concept a bit closer.
  - cratermoon 3y ago
    Yes, but space is still vast. The chance of one hitting earth is infinitesimal. Also, "they are free" isn't strictly true. Where do they get the resources to reproduce? Using unbounded exponential math implies a sort of paperclip maximizer that would eat up everything in its path.
    - Teever 3y ago
      But the point of sending out Von Nuemann probes is to send them to every star in a galaxy, so that you can watch the goings on of all those stars. That means that any Von Neumann plan in the Milky Way will involve Earth. > Where do they get the resources to reproduce? From the the star systems that they reach. Stars provide the energy and whatever detritus in the form of an asteroid belt that orbits the star will provide the material to build new probes.
dvh 3y ago
We are too early. It took earth 4.5 billion years to develop electronics. That's only 2x more than age of the universe.
- ericb 3y ago
  The dinosaurs were dominant 250 million years ago. If humans had come first instead of dinosaurs and built von Neumann probes at that time, our probes could be saturating scores other galaxies--not stars, galaxies by now. That's with only a 250 million year differential in technology emergence. It isn't hard to imagine the emergence of technology varying by even more than that. https://en.wikipedia.org/wiki/List_of_nearest_galaxies https://en.wikipedia.org/wiki/List_of_nearest_galaxies
zabzonk 3y ago
i have never understood the possible motivations for developing and launching VN probes. if anyone would like to explain here, i'd be interested.
- ericb 3y ago
  Curiosity. Scientific exploration. Detection. Defense. Finding a new home. Meeting the neighbors. We're already sending probes to Mars, so I imagine we would send VN probes if we had them, so it doesn't seem like much of a stretch.
  - zabzonk 3y ago
    yes, but they travel slowly and have to somehow (never clearly stated how) communicate back to home. as they spread out, the comms stuff becomes more and more problematic.
    - ericb 3y ago
      That's a fair point. If they are autonomous and carrying out a mission on your behalf, perhaps they don't need to communicate back to be useful. Might still leave defense, advance scouting, resource location (a broad search), panspermia, or other possibilities.
    - matthewdgreen 3y ago
      If they work anything like any natural or artificial communications system we’ve built, each new “node” would immediately establish a connection to the nearest colonized star system. Light speed delays would still matter, but any important news and communications would get delivered.
      - krapp 3y ago
        A communications network that works with an average latency of five years (the average distance between stars), and an edge case of millions of years would be all but useless. The civilization that started it might not even be the civilization that receives the first message, or even the same species. And what does "important news and communications" even mean with that kind of latency? Also there is signal degradation to consider. Depending on their broadcast strength, there is a limited range beyond which any signal they send will be indistinguishable from background noise. According to this quora post[0] that limit could be as little as four light years. It certainly would not work on any significantly pan-galactic scale. Lasers would fare little better, they would also diffuse and be absorbed by interstellar material. Also, at that scale, whatever message gets sent may no longer be relevant, or factual, by the time it's received. A lot can happen in a million years. It's difficult for me to think of a message worth sending that also doesn't matter if it takes longer than the time it took humans to evolve to get from point to point. [0]https://www.quora.com/How-far-do-radio-signals-travel-into-space-before-they-degrade-to-a-degree-beyond-being-possible-to-be-detected https://www.quora.com/How-far-do-radio-signals-travel-into-s...
hackerlight 3y ago
My issue with this thesis is it anthropomorphizes intentions and capabilities. We're predicting the behavior of civilizations a lot more advanced than us. We need a level of humility to realize that this is a lost cause, and a lot of the paradigms we take for granted will be shown to be false. So while everything you said makes sense, the space of unknown unknowns is so large that we should moderate our confidence in the underlying assumptions downwards.

by ericb 3y ago

seventytwo 3y ago

Big “if”.

ericb 3y ago
Which one? They all seem more likely than not.
- deleted 3y ago
  [deleted]

actionfromafar 3y ago

Why should they be here? That seems a stretch to me. We don't know the motivations by those who could send them.

thriftwy 3y ago
It makes sense to send them everywhere to have a sensor network wherever you go. The only reason why they may not be out there is because of Great Filter or because we are the first ones in our vicinity (would not be strange as our Universe is fairly young).
- actionfromafar 3y ago
  Or they are scared of what they might find. Whenever I read "the only reason" I have doubts. How can we be so sure?
  - thriftwy 3y ago
    I wonder what you are having in mind regarding what they can find. Can an automated probe have a mental breakdown?
    - actionfromafar 3y ago
      I should have written "might encounter". What I'm getting at is that if someone sees your probe, you have now let on that you exist.
ericb 3y ago
We have observed exactly one sentient species, (ours) and it is sending probes already. There are 200 sextillion stars. For the opposite position (they shouldn't be here) to make sense, there has to be either no other civilizations, or our probe-sending habits are so rare that no other civilizations do it, or we are the first. Any of those other stances seem vastly more improbable, as they assume that our sample-of-one society just happens to be ludicrously different than all others.
- actionfromafar 3y ago
  Since we have only a sample of one, I can never make my mind up on about what is probable or improbable. But I do believe it is technically possible in principle to construct and build von Neuman probes. Once they work inside a solar system, then work on making them withstand, say, a few million years in orbit and see if they still work, once they survive a few million years "inactive" (or constantly repairing themselves or whatever it takes), send them off to the stars. But it would take a patience and scale of industry we humans literally can only vaguely dream of.
  - ericb 3y ago
    > withstand, say, a few million years in orbit > ...scale of industry They don't have to do that. The probe just has to make more "child probes" before it dies. You don't need a huge industry if they are self-replicating. You need only one working probe to start, the rest handles itself.
    - actionfromafar 3y ago
      The "only" there does a lot of work. :-) And it has to survive for millions of years until it reaches a new solar system without something to "feed" on. In many ways it seems easier to make a Neuman probe which can survive within a solar system than something which can travel to another.
      - gremlinsinc 3y ago
Teever 3y ago
We do know the motivations to some degree because they're constrained by physical reality, evolution, and game theory. Von Nuemann probes are possible in this physical reality for a relatively cheap cost and small time frame. It makes sense to put probes that can watch for threats anywhere you think that threats can be. Species that do this have a greater chance of survival than species that don't.
gfodor 3y ago
They should be here to ensure we don’t do anything that could hurt anyone not on Earth’s surface.

cratermoon 3y ago

Space is far, far larger than the mind can easily conceive. To "von Neuman probes should be here" is to fail to comprehend just how improbable it would be for a spacecraft to be aimed at Earth.

ericb 3y ago
You don't aim a von Neuman probe anywhere. You use unbounded exponential math to send them everywhere as they are free. It seems like you might find the idea interesting if you look into the concept a bit closer.
- cratermoon 3y ago
  Yes, but space is still vast. The chance of one hitting earth is infinitesimal. Also, "they are free" isn't strictly true. Where do they get the resources to reproduce? Using unbounded exponential math implies a sort of paperclip maximizer that would eat up everything in its path.
  - Teever 3y ago
    But the point of sending out Von Nuemann probes is to send them to every star in a galaxy, so that you can watch the goings on of all those stars. That means that any Von Neumann plan in the Milky Way will involve Earth. > Where do they get the resources to reproduce? From the the star systems that they reach. Stars provide the energy and whatever detritus in the form of an asteroid belt that orbits the star will provide the material to build new probes.

dvh 3y ago

We are too early. It took earth 4.5 billion years to develop electronics. That's only 2x more than age of the universe.

ericb 3y ago
The dinosaurs were dominant 250 million years ago. If humans had come first instead of dinosaurs and built von Neumann probes at that time, our probes could be saturating scores other galaxies--not stars, galaxies by now. That's with only a 250 million year differential in technology emergence. It isn't hard to imagine the emergence of technology varying by even more than that. https://en.wikipedia.org/wiki/List_of_nearest_galaxies https://en.wikipedia.org/wiki/List_of_nearest_galaxies

zabzonk 3y ago

i have never understood the possible motivations for developing and launching VN probes. if anyone would like to explain here, i'd be interested.

ericb 3y ago
Curiosity. Scientific exploration. Detection. Defense. Finding a new home. Meeting the neighbors. We're already sending probes to Mars, so I imagine we would send VN probes if we had them, so it doesn't seem like much of a stretch.
- zabzonk 3y ago
  yes, but they travel slowly and have to somehow (never clearly stated how) communicate back to home. as they spread out, the comms stuff becomes more and more problematic.
  - ericb 3y ago
    That's a fair point. If they are autonomous and carrying out a mission on your behalf, perhaps they don't need to communicate back to be useful. Might still leave defense, advance scouting, resource location (a broad search), panspermia, or other possibilities.
  - matthewdgreen 3y ago
    If they work anything like any natural or artificial communications system we’ve built, each new “node” would immediately establish a connection to the nearest colonized star system. Light speed delays would still matter, but any important news and communications would get delivered.
    - krapp 3y ago
      A communications network that works with an average latency of five years (the average distance between stars), and an edge case of millions of years would be all but useless. The civilization that started it might not even be the civilization that receives the first message, or even the same species. And what does "important news and communications" even mean with that kind of latency? Also there is signal degradation to consider. Depending on their broadcast strength, there is a limited range beyond which any signal they send will be indistinguishable from background noise. According to this quora post[0] that limit could be as little as four light years. It certainly would not work on any significantly pan-galactic scale. Lasers would fare little better, they would also diffuse and be absorbed by interstellar material. Also, at that scale, whatever message gets sent may no longer be relevant, or factual, by the time it's received. A lot can happen in a million years. It's difficult for me to think of a message worth sending that also doesn't matter if it takes longer than the time it took humans to evolve to get from point to point. [0]https://www.quora.com/How-far-do-radio-signals-travel-into-space-before-they-degrade-to-a-degree-beyond-being-possible-to-be-detected https://www.quora.com/How-far-do-radio-signals-travel-into-s...

hackerlight 3y ago

My issue with this thesis is it anthropomorphizes intentions and capabilities. We're predicting the behavior of civilizations a lot more advanced than us. We need a level of humility to realize that this is a lost cause, and a lot of the paradigms we take for granted will be shown to be false. So while everything you said makes sense, the space of unknown unknowns is so large that we should moderate our confidence in the underlying assumptions downwards.