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Comment by phantarch | Hacker News Reader

As a counter point, it's always possible that a civilization that developed past where we are now would have been masterful at space travel, but not advanced enough to completely figure out a 1400 light year long journey. We're still having hard times figuring how to get squishy meat sacks to Mars without being irradiated to death or creating a launch vehicle made of lead. Besides the engineering problems there's the social cost of a venture like that. Unless their societies would be structured in a wholly different way (which is likely) then there is significant political and social momentum that would need to go behind a project like a mission where the minimum acknowledgement time of success is 2800 years away. There's plenty of time to go extinct or make yourself die off.

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You don't have to figure out a 1400-ly trip to be here. You just ("just") need to be able to move from one star system to the next.

If they took 100 years to get to the next star system 5-ly away and then 500 years to populate that system enough to start a new colonization, that's just ("just") 168,000 years to be here. Given a 2 billion year head start, that's easy.

Even if it only took them 100 years to get to a star system 5 ly away, I would be amazed and impressed by a society that would be okay with investing in and working on at minimum a 105 year mission. Perhaps they live much much longer than we do :)

If they lived much longer, comparisons on earth would lead one to expect they'd be much slower to get anything done. Small burrowing rodents that live a couple of years hit the ground running, build extensive dens, and reproduce before they're a year old. OTOH giant tortoises never actually do anything except walk around slowly.

>working on at minimum a 105 year mission

Cathedral building in the middle-ages was a multi-generational 80+ year affair and some of the Pyramids took even longer IIRC. So societies were/are definitely capable of working on ~100 year missions :)

Or the Sagrada Familia in Barcelona for a contemporary and in-progress example.

Maybe a generation ship needs to have some sort of 'cathedral-in-the-sky' religion connotation in order for us to commit to building it. Sounds like an interesting idea for a sci-fi plot!

> We're still having hard times figuring how to get squishy meat sacks to Mars without being irradiated to death or creating a launch vehicle made of lead.

But we've only been working on that for a few decades. 2 billion years is a lot longer. If there is a civilization there at all, it's extremely improbable that it hasn't figured out how to do exploration on a scale of thousands of light-years.

There's an implicit assumption running through most of this thread that if there's a civilization there, it's enjoyed 2 billion years of continuity.

I suspect that's unlikely, even if there were advanced life there for 2 billion years.

> I suspect that's unlikely, even if there were advanced life there for 2 billion years.

Why do you think so? "Continuity" doesn't have to be having the same government or the same political structure, or even the same physical form (the article itself talks about uploads and nanomachines). It just means continuity of technological development. It doesn't have to mean steady progress either; our civilization hasn't had that, yet in ten millennia or so we have progressed from basic agriculture to space travel. For this planet, we're talking about two million millennia, or 200,000 times the time we've had. All the variables we've observed in our civilization's history become rounding error on that timescale.

Yes, I mean continuity of technological development. I suspect that the prior millennium’s dark ages are but a pale inkling of how far a civilization can collapse, especially given geological time scales. I also suspect that technological development can plateau for sociological reasons.

Even during the dark ages here on Earth, there was technological advancement. Also, the dark ages weren't worldwide. I would be skeptical of a plateau in technological development for any significant length of time for the same reason: even if one part of the planet was in one, the rest of it wouldn't be.

On those timescales mass extinction events (asteroid, supervolcano etc.) become rather probable, which I guess could be what GP was trying to say.

A mass extinction event would mean there wouldn't be a civilization on the planet at all. That's certainly possible, but for this particular subthread I am taking as a premise that there is a civilization there.

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