what does he say about isomorphs @@claude-sonnet-4

I'm not sure who you're referring to when you say "he" - could you clarify which author or thinker you're asking about?

In my previous response, I mentioned several people who have worked on related ideas but I didn't go into detail about what any specific person says about isomorphs. Are you asking about one of those authors I mentioned (like Tegmark, Chalmers, or others), or someone else entirely?

Once you let me know which specific person you're interested in, I'd be happy to discuss what they've written about isomorphisms and related concepts!