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The assumption is not just about being able to identify civilizations out there. It also assumes that someone should have come to us by now. (Any theory that th

The assumption is not just about being able to identify civilizations out there. It also assumes that someone should have come to us by now. (Any theory that thousands of other civilizations out there just wouldn't be interested in exploring / expanding / communicating / etc requires every single civilization out there to be that way.)

krapp 6y ago
>(Any theory that thousands of other civilizations out there just wouldn't be interested in exploring / expanding / communicating / etc requires every single civilization out there to be that way.) Space is difficult, interstellar space exponentially more so. It isn't necessary to make any claims about any or all civilizations if the nature of physics alone makes it extremely unlikely for any species, however curious, to ever make it out of their local gravity well, much less sustain the technological infrastructure, knowledge base, energy consumption, unified political will (despite vast cultural and biological evolution) and control over every other variable across millions of years as a species to be able to stumble across our planet even once among the billions upon billions of galaxies' worth of stars in the observable universe. One might say "it only has to happen once." I submit that it could have happened a thousand times and we could still never know.
- gfodor 6y ago
  In this sense, there's a variant of the Great Filter where the Filter isn't the existence of other civilizations, but over the probability mass they'll cross paths with another and each can mutually grok the other exists. Arguably this is a much more grounded way to view the Filter theory, since it's less assumption-laden. It also surfaces the assumptions of the usual Filter theory more starkly. We only recently even became intelligent enough for the concept of us recognizing another civilization to even make sense.
  - krapp 6y ago
    I think people intuitively perceive the universe as being roughly analogous to Earth's oceans. Obviously we know it isn't objectively true, but subjectively we're just not capable of comprehending the true scale and emptiness of space, of reconciling the Hubble Deep Field image[0] with the fact that less than 5% of the entire universe is physical matter. Even the distance between the Earth and Moon is mind-boggling on human scales, and humans have traveled it. So it seems reasonable that if any interstellar civilization were out there, one would have found us by now, or their presence would be obvious to us. After all, Rome knew of China, even if they never directly interacted, and Spain eventually stumbled across the New World. Von Neumann probes make sense because it doesn't occur to us that the chances of any arbitrary path along the universe intersecting with a star would be effectively zero. We look up at the night sky and we can see so many of them, and they seem so close together, obviously you'd run into one no matter which way you went, sooner or later. Right? It's more comforting to make up rationales as to why we might be alone than deal with the ramifications of being surrounded by life we may never see in a universe in which the entirety of physical reality amounts to a rounding error in a zero. [0]https://en.wikipedia.org/wiki/Hubble_Deep_Field https://en.wikipedia.org/wiki/Hubble_Deep_Field [1]https://www.theatlantic.com/technology/archive/2014/12/the-chance-of-a-collision-in-outer-space-is-practically-zilch/383810/ https://www.theatlantic.com/technology/archive/2014/12/the-c...
    - bena 6y ago
      True, the one thing I keep trying to remind myself and other of is that we really don't appreciate the cosmic scale all that well. There's a point where it's all just "big". A million and a billion seem equally big. Even though, as it has been said before, that the difference between 1 billion and 1 million is about 1 billion. There are so many fundamentally difficult problems with deep space exploration, that it may never be logistically possible to over come them. And that's of the ones we know about.
    - MiroF 6y ago
      We're not capable of comprehending the true scale/emptiness of space, sure - but it seems like many commentators are having difficulty comprehending the length of time the universe has been around for. If a single civilization in our galaxy made a machine capable of replicating itself and going to other star systems less than a billion years ago, we should have seen that. > it doesn't occur to us that the chances of any arbitrary path along the universe intersecting with a star would be effectively zero I fail to see how this is a strong critique of Von Neumann probes, maybe you can clarify.
  - MiroF 6y ago
    > Filter isn't the existence of other civilizations, but over the probability mass they'll cross paths with another and each can mutually grok the other exists The idea is that "probability mass they'll cross paths with another and each can mutually grok the other exists" is a monotonically increasing function of the number of other civilizations, which bridges the problem you've identified.
- MiroF 6y ago
  This is entirely consistent with the great filter. > 1. it extremely unlikely for any species, however curious, to ever make it out of their local gravity well ie. it is more likely that they would go extinct before making it out of their local gravity well, which means the discovery of other life local to us would make it substantially more likely that filter preventing us from attaining interstellar travel is ahead of us.

krapp 6y ago

>(Any theory that thousands of other civilizations out there just wouldn't be interested in exploring / expanding / communicating / etc requires every single civilization out there to be that way.) Space is difficult, interstellar space exponentially more so. It isn't necessary to make any claims about any or all civilizations if the nature of physics alone makes it extremely unlikely for any species, however curious, to ever make it out of their local gravity well, much less sustain the technological infrastructure, knowledge base, energy consumption, unified political will (despite vast cultural and biological evolution) and control over every other variable across millions of years as a species to be able to stumble across our planet even once among the billions upon billions of galaxies' worth of stars in the observable universe. One might say "it only has to happen once." I submit that it could have happened a thousand times and we could still never know.

gfodor 6y ago
In this sense, there's a variant of the Great Filter where the Filter isn't the existence of other civilizations, but over the probability mass they'll cross paths with another and each can mutually grok the other exists. Arguably this is a much more grounded way to view the Filter theory, since it's less assumption-laden. It also surfaces the assumptions of the usual Filter theory more starkly. We only recently even became intelligent enough for the concept of us recognizing another civilization to even make sense.
- krapp 6y ago
  I think people intuitively perceive the universe as being roughly analogous to Earth's oceans. Obviously we know it isn't objectively true, but subjectively we're just not capable of comprehending the true scale and emptiness of space, of reconciling the Hubble Deep Field image[0] with the fact that less than 5% of the entire universe is physical matter. Even the distance between the Earth and Moon is mind-boggling on human scales, and humans have traveled it. So it seems reasonable that if any interstellar civilization were out there, one would have found us by now, or their presence would be obvious to us. After all, Rome knew of China, even if they never directly interacted, and Spain eventually stumbled across the New World. Von Neumann probes make sense because it doesn't occur to us that the chances of any arbitrary path along the universe intersecting with a star would be effectively zero. We look up at the night sky and we can see so many of them, and they seem so close together, obviously you'd run into one no matter which way you went, sooner or later. Right? It's more comforting to make up rationales as to why we might be alone than deal with the ramifications of being surrounded by life we may never see in a universe in which the entirety of physical reality amounts to a rounding error in a zero. [0]https://en.wikipedia.org/wiki/Hubble_Deep_Field https://en.wikipedia.org/wiki/Hubble_Deep_Field [1]https://www.theatlantic.com/technology/archive/2014/12/the-chance-of-a-collision-in-outer-space-is-practically-zilch/383810/ https://www.theatlantic.com/technology/archive/2014/12/the-c...
  - bena 6y ago
    True, the one thing I keep trying to remind myself and other of is that we really don't appreciate the cosmic scale all that well. There's a point where it's all just "big". A million and a billion seem equally big. Even though, as it has been said before, that the difference between 1 billion and 1 million is about 1 billion. There are so many fundamentally difficult problems with deep space exploration, that it may never be logistically possible to over come them. And that's of the ones we know about.
  - MiroF 6y ago
    We're not capable of comprehending the true scale/emptiness of space, sure - but it seems like many commentators are having difficulty comprehending the length of time the universe has been around for. If a single civilization in our galaxy made a machine capable of replicating itself and going to other star systems less than a billion years ago, we should have seen that. > it doesn't occur to us that the chances of any arbitrary path along the universe intersecting with a star would be effectively zero I fail to see how this is a strong critique of Von Neumann probes, maybe you can clarify.
- MiroF 6y ago
  > Filter isn't the existence of other civilizations, but over the probability mass they'll cross paths with another and each can mutually grok the other exists The idea is that "probability mass they'll cross paths with another and each can mutually grok the other exists" is a monotonically increasing function of the number of other civilizations, which bridges the problem you've identified.
MiroF 6y ago
This is entirely consistent with the great filter. > 1. it extremely unlikely for any species, however curious, to ever make it out of their local gravity well ie. it is more likely that they would go extinct before making it out of their local gravity well, which means the discovery of other life local to us would make it substantially more likely that filter preventing us from attaining interstellar travel is ahead of us.