Dissolving the Fermi Paradox

Dissolving the Fermi Paradox
arxiv.org

This is very sobering to read if true. It’s all on us. Life is even more precious than we thought and every human life extinguished even more of a loss to the universe. If we could only band together and see this.

Opinions like these (I stop one step short of calling them findings, as this is speculation either way) resonate with me. I'm, too, more convinced by the Rare Earth hypothesis, and I find it quite plausible that we're indeed the sole sentient lifeform in the Universe - at least throughout the time of our existence.

This belief never gained me much popularity though. And this is what I'm fascinated about - how badly a lot of people take to this view. Even seemingly rational individuals seem to have some deeply ingrained, emotional need to defend the belief in ETI.

My personal theory is that this emotional mechanism is actually of religious nature; just in disguise. It's very telling that the most popular narratives involving ETI are usually quasi-religious.

The aliens would typically "teach us how to live in peace" (if we're willing to sit down and listen, of course), or turn away from us in disgust (for our sins), or scold us for our poor moral judgment and deeds; generally trap us in shame. Or they'd be quite diabolical and bring all sorts of plagues upon us, giving us a taste of our own medicine for we're wicked.

But the eschatological component is rarely absent either way.

Even this sceptical paper uses biased language through and through, consistently referring to the belief in the prevalence of ETI as "optimistic", and calling the opposite belief "pessimistic". But why?

There are so many other explanations for Fermi Silence - from the reality of extremely limited sampling to the creeping suspicion that we're too mediocre and underdeveloped to recognise truly intelligent life - that grand assumptions about our specialness seem more than a little premature.

None of this requires aliens who will teach us anything, one way or the other. It requires aliens who ignore us because we're about as interesting as a termite mound.

And once you've seen a few billion of those, you've more or less seen them all.

Longer comment:

The paper considers each parameter of the Drake as a probability distribution over some range. Notably, they assume that f_l in the Drake equation (the fraction of habitable planets that actually develop life) may vary over (at least) 200 orders of magnitude. Yes, you read that correctly.

Naturally, they thereby get a long tail of "planets essentially never develop life, even despite there being so many of them".

My main critique (as someone with no further credentials) is that the prior probability distributions they assume for the parameter distributions are more or less meaningless. Their results say "if we assume that the log of f_i (life-bearing planets that develop intelligent life) is uniformly distributed between log(0.001) and log(1), similar for other parameters, then the probability of being alone in the milky way is > 50%".

Specifically, by far the largest impact here is from assuming some distribution for f_l that covers 10x as many orders of magnitude (!) as the remaining parameters together. I'm very certain (but haven't done the math) that slightly tweaking the sigma they assume for the corresponding log-normal distribution (that sigma is 50 orders of magnitude) would drastically impact the results. They do a lot of dancing around that fact (discussing how little impact the priors of other parameters, or even the center of the log-normal distribution for f_l have), but fundamentally the result boils down to:

"We're extremely unsure how often abiogenesis happens, and this parameter dominates everything else." Followed by some math that (oversimplified) boils down to "if we set the rate of abiogenesis to effectively zero half the time, then half the time we are alone in the universe."

PS: Title should probably have (2018).