Drake equation wrong interpretation: The mean of multiplication is not multiplication of the mean
As I’ve previously written, I disagree that this constitutes a separate explanation. This paper is just saying as far as we know, one or more of the Drake equation parameters might be very much lower than Drake’s guess. But yeah duh, the whole point of this discourse is to figure out which parameter is very much lower and why. Pretty much all the other items on your list are engaged in that activity, so I think this box is an odd one out and should be deleted. (But if you’re trying to do a lit review without being opinionated, then I understand why you’d keep it in. I just like to rant about this.)
Multicellular life is difficult
In The Vital Question, Nick Lane argues (IMO plausibly) that the hard step is not multicellular life per se but rather eukaryotes (i.e. cellular life with at least two different genomes). Not all eukaryotes are multicellular, but once eukaryotes existed, they evolved multicellularity many times independently (if I recall correctly).
Space travel is very difficult for unknown reasons
AFAICT, “interstellar travel is impossible or extremely slow because there’s too much dust and crap in space that you’d collide with” remains a live possibility that doesn’t get enough attention around these parts.
My goal was to list all possible solutions here, but not to estimate them. However, in the really great post by Lukas there is a Monte Carlo model of distribution of different values in the Drake equation which creates two hills - one hill is ( as I understand the post) for all of the parameters are close to 1 habitable planet per star and another is 10exp(-100) where at least one is extremely low. This, however, is compensated by anthropic considerations which favor maximal concentration of habitable planets.
I don't see eukaryotes as a really hard step as symbiosis between cells seems a logical step.
Space travel in the dust may be solved by use of needle-like nanotechnological starships. They also can self-repair if collide small dust particles or gas. As we can see remote stars, most straight lines to them are dust free so the problems can be solvable. An alternative is sending heavy Orion-like nuclear ships and limit their speed to 0.1c. Heavy ship can carry heavy protection ahead it.
See here AI-updated version of the map which includes probabilities and Global vs Local solution distinctions. If you press on any text it will provide more detailed explanation. But this AI-version may have subtle errors. Probabilities are AI-generated and just illustrative.
https://avturchin.github.io/OpenSideloading/fermi_v11_en_interactive.html
I can but it will look like dark forest of text - from previous experience. Which point are not clear?
I also have AI-enhanced version of the map with generated probabilities and I can ask it to add explanations.
I second this and would at least like a version where all the blue words, presumably links, take you to the explanation if one exists.
Edit: I did not click the link, of course you have to click the link, this is my fault
I heard that there are around 100 solutions of the Fermi paradox. Here I tried to collect the largest possible list and I am open to the new suggestions. Download pdf with links here.
Also, see here AI-updated version of the map which includes probabilities and Global vs Local solution distinctions. If you press on any text, it will provide more detailed explanations. But this AI-version may have subtle errors. Probabilities in it are AI-generated and are just illustrative.
