
Study predicts at least 36 civilizations within our Galaxy - gtirloni
https://iopscience.iop.org/article/10.3847/1538-4357/ab8225
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pjdorrell
Useful arxiv link:
[https://arxiv.org/abs/2004.03968](https://arxiv.org/abs/2004.03968)

As always, the critical assumption is f_l, the probability that life of any
kind will originate on a "suitable" planet.

The authors invoke the "Principle of Mediocrity", which says something like,
"We're not special, therefore f_l = 1".

This is exact opposite of the Anthropic Principle, which says: "From the
observation that life has originated on Earth, we can deduce nothing at all
about f_l."

If f_l is some other number, like 0.00000000000000000000000000000000000000001,
then the expected number of alien civilisations won't be 36, it will be
0.00000000000000000000000000000000000000036.

Also 0.00000000000000000000000000000000000000001 could be wildly optimistic.
The true value might have so many zeroes after the decimal point that it
exceeds the permitted size of Hacker News comments.

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gus_massa
> _we find there should be at least ${36}_{-32}^{+175}$ civilizations within
> our Galaxy_

It looks more like "at least 4" for me.

