I'm not sure the term "emergent" is a term in theoretical physics. I've certainly never seen it. >'All phenomena are emergent' with this definition of the word

I'm not sure the term "emergent" is a term in theoretical physics. I've certainly never seen it. >'All phenomena are emergent' with this definition of the word would mean you could always represent something with something else that is more basic, ad infinitum No, what it means is that at some point, you've broken your model down into something that is not 'phenomena' in any meaningful sense. Which is something physicists do all the time.