My own favorite hypothesis goes like this: Our universe is most likely to be the simplest one that contains me (us, observers, conscious beings, whatever your favorite rendition of the anthropic principle). It is not likely to be much larger than necessary for creating me. The reason it is as large as it is, then, is that that's what it takes. The answer, then, is that something like me exists only once. More would be a waste of universal size and/or complexity, and Occam forbids it.

Is this as crazy as it sounds?

Also, seeing stuff like this really bugs me:

top of page 2: "Recent analyses of the Kepler statistics showed that about 20% of all Sun-like stars have Earth-sized planets orbiting within the habitable zone [Petigura, Howard and Marcy 2014]."

2nd paragraph of page 3: "Analyses of the Kepler results shows that 7-15% of the Sun-like stars have an Earth-sized planet within their habitable zone [Petigura et al., 2014]"

That's a pretty glaring error to be making. This isn't a top journal, but it isn't an obscure one either. http://eigenfactor.com/rankings.php?bsearch=International+Journal+of+Astrobiology&searchby=journal&orderby=eigenfactor

We may not have good measures for estimating Fb or Lb let alone Lc, but the Kepler mission gives us a pretty good estimate of Rb. You should update your estimate of the closeness of a biotic planet depending on whether your Rb prior was higher or lower than the result.

The key obstacle here is startup money. If self-replication is economically sound, then a convincing business case could be made, leading to startup funding and a trillion-dollar business.

Again, the problem is a realistic economic assessment of development cost and predicted profit. In the current funding market, there is a lot of capital chasing very few good ideas. If there is money to be made here (a big if, given low cost of manual labor) then this could be a good opportunity.

"Mining the moon" is probably too expensive to start up. Better to start with a self-replicating robot factory on Earth.

I might look at this financial analysis as a side project. Contact me if you want to get involved and have sufficient industry experience to know what you don't know.

Building a self-replicating lunar mining & factory complex is one thing. Building a self-replicating machine that is able to operate effectively in any situation it encounters while expanding into the cosmos is another story entirely. Without knowing the environment in which it will operate, it'll have to be able to adapt to circumstances to achieve its replication goal in whatever situation it finds itself in. That's the definition of an AGI.

Hmm, it is interesting that that exists but it seems like it is cannot have been very serious because it dates from over 30 years ago and no followup activity happened.

Therefore, certainty we can do that would eliminate much existential risk.

It seems to me that you are making a map-territory confusion here. Existential risks are in the territory. Our estimates of existential risks are our map. If we were to build a self-replicating spacecraft, our estimates of existential risks would go down some. But the risks themselves would be unaffected.

Additionally, if we were to build a self-replicating spacecraft and become less worried about existential risks, that decreased worry might mean the risks would become greater because people would become less cautious. If the filter is early, that means we have no anthropic evidence regarding future existential risks... given an early filter, the sample size of civilizations that reach our ability level is small, and you can't make strong inferences from a small sample. So it's possible that people would become less cautious incorrectly.

So what happens if we find all these biologically feasible exoplanets that just don't have any life on them?

BTW, you might want to give Matthew Stewart's book Nature's God a read. He points to the unexpected fact that many of the Americans in revolutionary times who wrote down their thoughts on the matter believed in "space aliens," as Stewart calls them, on exoplanets throughout the universe, and that these colonial Americans considered this arbitrary belief "rational" because of the peculiar way early modern philosophy originated from the revival of Epicureanism around the beginning of the 17th Century.

Reference:

http://books.google.com/books?id=L69bAwAAQBAJ&pg=PT45&lpg=PT45&dq=matthew+stewart+space+aliens&source=bl&ots=ruXJKJ-oGO&sig=LiQm__PtCVmXuVVGmEAueb2sLtY&hl=en&sa=X&ei=KHCCVJnhBsvhoATsjICwCA&ved=0CCoQ6AEwAg#v=onepage&q=matthew%20stewart%20space%20aliens&f=false

Estimates? Here some quotes from the paper on those "estimates":

"Also Lc, the average longevity of a communicative civilization, cannot be inducted from its short history on Earth and could be anywhere between a few hundred years and billions of years."

"Bayesian analysis demonstrates that as long as Earth remains the only known planet with biotic life, any value could be assigned to Fb"

You tell me how valuable these estimates are, in view of their precision....