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Yeah, this is where I've landed on Fermi. It's very likely life exists elsewhere - possibly even on moons in our solar system. And it's somewhat likely intell

Yeah, this is where I've landed on Fermi. It's very likely life exists elsewhere - possibly even on moons in our solar system. And it's somewhat likely intelligent life exists in other solar systems. But physics is such that it is much less likely two intelligences will be able to talk to eachother much less reach eachother. To quote Douglas Adams: Space is really big. You just won't believe how vastly hugely mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist, but that's just peanuts to space."

puglr 4y ago
It routinely bothers me a bit that, IME, most IRL discussions of the Fermi paradox tend to omit this rather simple explanation. Half the time it's brought up, FTL is offered as the solution. Which as best we can tell is fundamentally impossible. That squishy or otherwise organic bodies are generally unable to travel interstellar distances has always seemed to me to be the simplest solution. Assuming intelligent life is out there, surely there are civilizations that have destroyed themselves and so on. But lack of FTL travel would be a common constraint, regardless of all other scenarios.
- pmontra 4y ago
  Even with FTL you have to know where to go. Let's say you do 100 solar systems per year (going somewhere close to the star and some local jumps to look around.) There are 100 billion stars in the Milky Way. It takes a billion years to sequentially scan the galaxy. Optimizations in the search algorithm to cut that number down to 100 years are left as an exercise ;-)
  - bottled_poe 4y ago
    Branching factor of two means around 30 hops to visit every star.
    - pmontra 4y ago
      2^30 probes at the final hop. Maybe those FTL ships will turn out to be cheap to build like in Vance's Demon Princes novels.
- jjoonathan 4y ago
  It routinely bothers me a bit that, IME, most IRL discussions of the Fermi Paradox settle on this rather simple explanation when the whole idea was that this "simple explanation" was extremely unlikely, pushing speculation to more complicated and interesting hypotheses. Emergence of life on Earth took 13.7 billion years, galactic colonization should only take millions of years. We should not expect to find the galaxy half-colonized, as this would be a staggering feat of synchronization. We should find the galaxy completely full or completely empty. It seems to be completely empty.
  - chrononaut 4y ago
    > Emergence of life on Earth took 13.7 billion years 13.7 billion years? Isn't that the age of the universe, and didn't life emerge on Earth only after about a billion years?
    - yreg 4y ago
      Yes, but the parent means we are 13.7B years late to the party. Other civs should have been spawned before Earth was formed.
    - jjoonathan 4y ago
      The formation of Earth wouldn't have been the starting gun for alien life evolving somewhere other than Earth.
  - withinboredom 4y ago
    I doubt a civilization could survive being multi-starred. If you can expend that kind of energy, a pilot with a bad day can destroy the whole planet. A pissed off colony in the asteroid belt can sling asteroids at the home planet, etc. I also think you’re making a lot of assumptions but the speed of light is quite limiting in every aspect. If it takes 40 years to send a message, you need to either live a ridiculously long time — in which case your birth rate will be quite low — or figure the colonization as a one-way trip. No one would colonize another star system just for kicks, there would need to be a reason and I can’t think of a reason to colonize an entire galaxy that would make sense for a whole civilization, especially when it takes multi-decades just to send a message one way.
pfdietz 4y ago
> It's very likely life exists elsewhere How can you support this statement? It requires that Origin of Life is sufficiently probable, and we cannot conclude that from the known evidence (that life originated early on Earth is not sufficient, as we don't know how long the conditions suitable for OoL persist in a new solar system.)
- shireboy 4y ago
  well, for some values of “very likely”. ;) I base it on extremophiles. Life exists in volcanic vents and freezing waters. So it seems possible that at least microbial life exists somewhere else in the universe. Either way, “is/has there been at least microbial life on Venus, Mars, or Jovian moons” seems like a solvable question in the next 100 years or so. The conditions for intelligent life seem much more narrow.
  - pfdietz 4y ago
    That doesn't say life is likely to arise. It just says that life as we know it can, once it arises, evolve to exist in some extreme environments.

puglr 4y ago

It routinely bothers me a bit that, IME, most IRL discussions of the Fermi paradox tend to omit this rather simple explanation. Half the time it's brought up, FTL is offered as the solution. Which as best we can tell is fundamentally impossible. That squishy or otherwise organic bodies are generally unable to travel interstellar distances has always seemed to me to be the simplest solution. Assuming intelligent life is out there, surely there are civilizations that have destroyed themselves and so on. But lack of FTL travel would be a common constraint, regardless of all other scenarios.

pmontra 4y ago
Even with FTL you have to know where to go. Let's say you do 100 solar systems per year (going somewhere close to the star and some local jumps to look around.) There are 100 billion stars in the Milky Way. It takes a billion years to sequentially scan the galaxy. Optimizations in the search algorithm to cut that number down to 100 years are left as an exercise ;-)
- bottled_poe 4y ago
  Branching factor of two means around 30 hops to visit every star.
  - pmontra 4y ago
    2^30 probes at the final hop. Maybe those FTL ships will turn out to be cheap to build like in Vance's Demon Princes novels.
jjoonathan 4y ago
It routinely bothers me a bit that, IME, most IRL discussions of the Fermi Paradox settle on this rather simple explanation when the whole idea was that this "simple explanation" was extremely unlikely, pushing speculation to more complicated and interesting hypotheses. Emergence of life on Earth took 13.7 billion years, galactic colonization should only take millions of years. We should not expect to find the galaxy half-colonized, as this would be a staggering feat of synchronization. We should find the galaxy completely full or completely empty. It seems to be completely empty.
- chrononaut 4y ago
  > Emergence of life on Earth took 13.7 billion years 13.7 billion years? Isn't that the age of the universe, and didn't life emerge on Earth only after about a billion years?
  - yreg 4y ago
    Yes, but the parent means we are 13.7B years late to the party. Other civs should have been spawned before Earth was formed.
  - jjoonathan 4y ago
    The formation of Earth wouldn't have been the starting gun for alien life evolving somewhere other than Earth.
- withinboredom 4y ago
  I doubt a civilization could survive being multi-starred. If you can expend that kind of energy, a pilot with a bad day can destroy the whole planet. A pissed off colony in the asteroid belt can sling asteroids at the home planet, etc. I also think you’re making a lot of assumptions but the speed of light is quite limiting in every aspect. If it takes 40 years to send a message, you need to either live a ridiculously long time — in which case your birth rate will be quite low — or figure the colonization as a one-way trip. No one would colonize another star system just for kicks, there would need to be a reason and I can’t think of a reason to colonize an entire galaxy that would make sense for a whole civilization, especially when it takes multi-decades just to send a message one way.

pfdietz 4y ago

> It's very likely life exists elsewhere How can you support this statement? It requires that Origin of Life is sufficiently probable, and we cannot conclude that from the known evidence (that life originated early on Earth is not sufficient, as we don't know how long the conditions suitable for OoL persist in a new solar system.)

shireboy 4y ago
well, for some values of “very likely”. ;) I base it on extremophiles. Life exists in volcanic vents and freezing waters. So it seems possible that at least microbial life exists somewhere else in the universe. Either way, “is/has there been at least microbial life on Venus, Mars, or Jovian moons” seems like a solvable question in the next 100 years or so. The conditions for intelligent life seem much more narrow.
- pfdietz 4y ago
  That doesn't say life is likely to arise. It just says that life as we know it can, once it arises, evolve to exist in some extreme environments.