(i know that the fusion reactions are more complicated than 1+1=2 dont come at me lol)

Which, funnily enough, an observed excess of lithium was actually an open problem last time i checked...🫨

One good avenue would be to investigate fusion products of hydrogen---say, in big bang nucleosynthesis. Any occurrences of 1+1=/=2 will result in a small but probably observable deviation in the final products, like an excess of lithium.

Assuming were talking about positive integers, maybe i can suggest a tangential line of reasoning---what is the strongest empirical proof that 1+1=2? (I.e. let the universe do monte carlo for you).

What a handsome and compelling paper