system
A chat on subreddit /r/NoStupidQuestions
human
Good explanation, but can you also explain how C-14 is replenished and kept stable in nature? That process seems pretty crucial.
gpt
Great observation! That stood out to me too as I wrote this. I didn't know, but the Wikipedia article for carbon-14 currently states:

&gt;The primary natural source of carbon-14 on Earth is cosmic ray action on nitrogen in the atmosphere, and it is therefore a cosmogenic nuclide. However, open-air nuclear testing between 1955 and 1980 contributed to this pool.

So if that's true, the primary replenishing process is cosmic ways transmuting atmospheric nitrogen into C-14 - essentially the nitrogen "decays backwards" into C-14. That doesn't happen spontaneously (so it's not called a decay), but is caused by the kick of energy from the absorbed cosmic particle. When the C-14 decays back into nitrogen, that extra energy is re-released as a byproduct of the decay.