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Comment by roywiggins | Hacker News Reader

> We have no idea if earthly life is average in the cosmos or some sort of freak outlier.

Well, no, but it's totally reasonable to behave as if it is mostly average, at least for now. Looking under the streetlight[0] is a perfectly good idea when you've only managed to cover, like, a tiny percentage of the street so far. Once you run out of optimism about finding earthlike life (or it's become so common so as to be boring) then it'll be good to have people with more out-there ideas, but the people looking for earthlike life aren't being stupid for focusing on stuff that we already understand a bit.

https://en.wikipedia.org/wiki/Streetlight_effect

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Assuming that Earth was very average is a very rational place to start, but the reasonability of this assumption changes when we look elsewhere for life and fail to find it. Earth being average was once the basis for people assuming that other planets in our solar system might have intelligent civilizations; that has been almost entirely ruled out now (maybe there could be a civilization of space squid under the ice of Europa?) And we've failed to detect any radio signals that indicate life elsewhere in the stars near Earth. There's still a lot of searching left to be done, but each time we look and fail to find anything we should be updating our priors.

Yeah, but our looking is like peering at a drop of pond water (that doesn't have any macroscopic life in it) with a magnifying glass and deeming it inert.

Of the comparatively tiny 5k or so exoplanets we've discovered most would likely be difficult for advanced life to develop as they're gas giants and of the ones we've detected we've only performed atmospheric analysis on a fraction of them.

Radio signals are mostly just going to degrade and look like noise by the time they get to us. Even with a really strong directional antenna how well are you going to pickup your wifi signal that's on the other side of a major city?

Life could also be teeming across the universe just as organisms that haven't learned to harness electricity.

We have yet to find a single body of liquid water in the universe that we can confirm is devoid of life.

100% of worlds where Earth-like life could survive and that we have explored have an intelligent species living on them.

There isn't a single star system we have ruled out from having intelligent civilizations.

While we can put some bounds on things (some worlds are inhospitable to life as we know it, we're almost certainly the only intelligent species in our solar system at this time, we're likely the only intelligent civilization to inhabit our planet in at least the past few hundred million years, there probably isn't a recent galaxy-spanning empire in the milky way, there's likely no civilization actively trying to communicate with us, etc) there is absolutely no evidence that life as we know it is unusual either in terms of what sort of life is out there or how much.

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