Re: biosignatures detected on K2-18b, there’s been a couple popular takes saying this solves the Fermi Paradox: K2-18b is so big (8.6x Earth mass) that you can’t get to orbit, and maybe most life-bearing planets are like that.
Assuming K2-18b does have life actually makes the Fermi paradox worse, because it strongly implies single-celled life is common in the galaxy, removing a potential Great Filter
Re: biosignatures detected on K2-18b, there’s been a couple popular takes saying this solves the Fermi Paradox: K2-18b is so big (8.6x Earth mass) that you can’t get to orbit, and maybe most life-bearing planets are like that.
This is wrong on several bases:
You can still get to orbit there, it’s just much harder (only 1.3g b/c of larger radius!) (https://x.com/CheerupR/status/1913991596753797383)
It’s much easier for us to detect large planets than small ones (https://exoplanets.nasa.gov/alien-worlds/ways-to-find-a-planet), but we expect small ones to be common too (once detected you can then do atmospheric spectroscopy via JWST to find biosignatures)
Assuming K2-18b does have life actually makes the Fermi paradox worse, because it strongly implies single-celled life is common in the galaxy, removing a potential Great Filter
Edit 5/24/25: Also it turns out the biosignatures might have just been noise anyway.