And we can split hairs and conclude that for "the last two billion years, on this planet, in this galaxy, the physics affecting nuclear decay have not changed"

And we can split hairs and conclude that for "the last two billion years, on this planet, in this galaxy, the physics affecting nuclear decay have not changed" It's great to know that say dating using carbon-14 decay is still useful over those time ranges on planet earth (I don't know if that is something we care about given that fossils don't tend to contain much carbon, but coal and oil deposits are around 400 million years old). I don't want to imply that this is too small of a sample size, but I will imply that nuclear decay, and the movement of galaxies across the universe might be unrelated. Don't know. Not sure how we'd measure that. Supernova observations would tell us about nuclear fusion and it's limits. Does it tell us about nuclear fission? I don't know.