Oh wow, I was really was tired when I wrote this. I meant to say atomic decay not radioactive decay. Though the fluctuation of radioactive decay is what original made me wonder about this.
https://en.wikipedia.org/wiki/Caesium_standard
"By definition, radiation produced by the transition...
Also, How do we know the radioactive decay is constant? I know that carbon dating cannot be 100% accurate because the rate of production fluctuates based on cosmic rays hitting our upper atmosphere. Why isn't this true with Earth metal isotopes?
Is time truly constant? It seems like a lot...