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Space is called space for a reason. I feel like even scientifically knowledgeable people have a hard time wrapping their heads around just how much space is out

by api 2y ago

Space is called space for a reason. I feel like even scientifically knowledgeable people have a hard time wrapping their heads around just how much space is out there. Here's a good place to start: https://joshworth.com/dev/pixelspace/pixelspace_solarsystem.html https://joshworth.com/dev/pixelspace/pixelspace_solarsystem.... Signals diminish with the square of distance. SETI would never hear anything from other stars unless it was broadcast with insanely high transmit power or was directed right at us (and still very powerful). Nobody would do that unless they knew someone was here actively listening. https://briankoberlein.com/blog/et-phone-home/ https://briankoberlein.com/blog/et-phone-home/ So for example, to reach the Centauri system (the nearest star) with a signal as powerful as the signal Voyager sends to Earth would require a transmit power of over 100 megawatts at a minimum. That's just the nearest star. It gets exponentially harder as you go further out. For more distant stars you're talking gigawatts or terawatts or beyond. Even barring concerns about attracting attention, why dedicate that kind of resources to operate an interstellar border blaster if you don't even have a reason to think anyone's listening, and if you won't get a reply for hundreds or thousands of years?

pfdietz 2y ago
This is not making a point you think it's making. If SETI is problematic, success becomes even more depressing, since it implies even more non-communicating civilizations out there (and, presumably, existing densely in the past as well). So why wasn't Earth colonized eons ago?
- api 2y ago
  Why would it be? It’s full of corrosive oxygen and biomass that would be a biohazard to anything carbon based and organic. It’s habitable to us because we evolved here but it might be toxic hell to something else. If you are going to sterilize Earth you might as well just terraform something dead. This isn’t even getting into the ethical questions, just looking at practicality. If you’ve got the technology to come here, well, you might as well terraform something dead. We almost have the technology to terraform Mars (albeit over thousands of years) and it seems easier to do and possibly faster than interstellar flight. Building giant space station habitats is also easier than interstellar flight. Uploading brains to machines, which would allow settlement of almost anywhere, is probably easier than interstellar flight. AGI is probably easier than interstellar flight. In fact interstellar flight is so hard it might rarely be attempted anywhere by anyone unless there’s a forcing function like one’s star becoming unstable or some other cosmic scale calamity. Solar systems are huge and contain vast amounts of resources.
  - pfdietz 2y ago
    Why would a colonizing civilization have to choose between these options? If it experiences relentless growth, it would occupy everything. If it has grown to occupy some locations around a large number of stars, that's enormous growth from its initial system. Why would this growth stop? Instead, I'd expect it to fully exploit all the resources in all the systems reached. The solar system would look very different from what it looks like. There would be no asteroid belt; there would be a space colony belt.
    - api 2y ago
      I suppose this does tell us something: there are no ancient super high tech hyper-expansionary civilizations in this galaxy, or at least not near us. That could mean a lot of things including just chance. There could be galaxies out there that have in fact been fully colonized.
      - rbanffy 2y ago
        Expanding is a significant use of resources. It requires consistent dedication over very long timeframes to succeed. Just look at how long it's taking to even have a permanent presence (not even close to a self-sustaining colony) on the Moon, which is one light-second away.
        api 2y ago
        That’s one reason I’m skeptical of ultra-grabby hyper-expansionist aliens. Human cultures have become less obsessively expansionist as they’ve become more educated and advanced, with rare and usually transient exceptions. Imperialism usually burns out after a while as the cost begins to exceed the benefit. I could see a universe of mostly steady state civilizations that experience occasional bouts of expansionism or the sending of things like the Nauvoo from The Expanse. But those are transient events. This would greatly increase the time required for the galaxy to become saturated with life as per Fermi paradox models. It might happen eventually, meaning if we wait long enough some alien Mormons might show up. (The Expanse reference.) Then consider that intelligence is probably a recent (on cosmic time scales) phenomenon due to metallicity. Previous generations of stars and planets probably lack the mineral diversity to support complex intelligent life.

by api 2y ago

pfdietz 2y ago

This is not making a point you think it's making. If SETI is problematic, success becomes even more depressing, since it implies even more non-communicating civilizations out there (and, presumably, existing densely in the past as well). So why wasn't Earth colonized eons ago?

api 2y ago
Why would it be? It’s full of corrosive oxygen and biomass that would be a biohazard to anything carbon based and organic. It’s habitable to us because we evolved here but it might be toxic hell to something else. If you are going to sterilize Earth you might as well just terraform something dead. This isn’t even getting into the ethical questions, just looking at practicality. If you’ve got the technology to come here, well, you might as well terraform something dead. We almost have the technology to terraform Mars (albeit over thousands of years) and it seems easier to do and possibly faster than interstellar flight. Building giant space station habitats is also easier than interstellar flight. Uploading brains to machines, which would allow settlement of almost anywhere, is probably easier than interstellar flight. AGI is probably easier than interstellar flight. In fact interstellar flight is so hard it might rarely be attempted anywhere by anyone unless there’s a forcing function like one’s star becoming unstable or some other cosmic scale calamity. Solar systems are huge and contain vast amounts of resources.
- pfdietz 2y ago
  Why would a colonizing civilization have to choose between these options? If it experiences relentless growth, it would occupy everything. If it has grown to occupy some locations around a large number of stars, that's enormous growth from its initial system. Why would this growth stop? Instead, I'd expect it to fully exploit all the resources in all the systems reached. The solar system would look very different from what it looks like. There would be no asteroid belt; there would be a space colony belt.
  - api 2y ago
    I suppose this does tell us something: there are no ancient super high tech hyper-expansionary civilizations in this galaxy, or at least not near us. That could mean a lot of things including just chance. There could be galaxies out there that have in fact been fully colonized.
    - rbanffy 2y ago
      Expanding is a significant use of resources. It requires consistent dedication over very long timeframes to succeed. Just look at how long it's taking to even have a permanent presence (not even close to a self-sustaining colony) on the Moon, which is one light-second away.
      - api 2y ago
        That’s one reason I’m skeptical of ultra-grabby hyper-expansionist aliens. Human cultures have become less obsessively expansionist as they’ve become more educated and advanced, with rare and usually transient exceptions. Imperialism usually burns out after a while as the cost begins to exceed the benefit. I could see a universe of mostly steady state civilizations that experience occasional bouts of expansionism or the sending of things like the Nauvoo from The Expanse. But those are transient events. This would greatly increase the time required for the galaxy to become saturated with life as per Fermi paradox models. It might happen eventually, meaning if we wait long enough some alien Mormons might show up. (The Expanse reference.) Then consider that intelligence is probably a recent (on cosmic time scales) phenomenon due to metallicity. Previous generations of stars and planets probably lack the mineral diversity to support complex intelligent life.