[jjaredsimpson]

I believe we are alone in Milky Way.

Self assembling replicators from some civilization should have colonized and cataloged every star system over billion year time scales.

It's inconceivable that no intelligent space faring civilization would have thought to do this.

[3pt14159]

Presuming we're not in a simulation then I think it is unlikely that we're alone in the Milky Way.

There are too many stars and too many close enough galaxies that could contain life. If they've been spacefaring for even ten thousand years longer than us then they're almost certainly able to monitor us without our ability to detect it.

But if we're doomed to a great filter in the near future, like nuclear war, then it still doesn't mean we're alone. It just means that out there in the sky there are others kinda like us. Searching for meaning before hitting a technological explosion of one kind or another that wipes us out. But just because we don't have contact doesn't mean we're alone, even if we're only present in each others respective imaginations.

[krapp]

It seems like you're assuming the difficult part about creating self-assembling replicators capable of sustained, error-free exponential growth across interstellar space and billions of years is merely coming up with the idea.

It's entirely conceivable that every space faring civilization which has tried has failed simply because the odds are so stacked against success, even once, at every step along that process. Just because the math is simple, doesn't mean the application is simple.

Hell, we don't even know what the odds are of becoming a space faring civilization to being with, and it doesn't seem axiomatic that every such civilization would even want to seed the galaxy with self-assembling replicators to begin with.

[jmmcd]

Maybe they did and it left no trace noticeable to us, or their policy is not to contact life-bearing planets, and did you read the article?

[semi-extrinsic]

I've been mulling this over: given the constraints of information travelling at lightspeed and physical objects travelling at a lot less, what if it simply doesn't make financial sense for any actor in a market economy to colonize the galaxy?

What if the ROI of space colonization even at multi-decade or multi-century timescales is negative? Then why would anyone do it?

[ncmncm]

Market economy is far from a law of nature. Even most human activity is cannot be understood as market driven.

[kochikame]

There doesn't have to be an economic motive

What if they just feel like exploring, and gaining knowledge, and seeing things no one else has ever seen?

[semi-extrinsic]

Well, they'd still have to be able to pay for everything they need to go off on that voyage.

[rthomas6]

But what if that happens once every, say, 2 billion years on average? What is the likelihood we exist in a time close enough to that happening for us to be able to find ruins of it? That is the point the article made. There is an assumption that, if that happens, the colonization is permanent. Maybe that's not a good assumption.

[m4rtink]

Alien ruins would be nice to explore but oh well. If it really is like that, we can at least spread through it in a relative peace. :)

[gnulinux]

Maybe they're in the process of doing that but it just so happened that they haven't cataloged our system yet.

[aeternum]

Plot-twist: We are those self-assembling replicators, and DNA/RNA is the deployment mechanism.