Regardless of what you call the universe, we already know 1. Everything we know about it comes from sensory input, and 2. That sensory input's production can be modeled mathematically. But it's hard for me to make sense of what author really means by the claim "the universe is math". He claims after pulling away notation math is "A set of abstract entities with relations between them". Great! But then again... any idea I can conceive of can be said to be abstract entities with relations between them. That's an awfully vague definition. Then it's as if he fills in the void with baggage from his subjective understanding of mathematical structures (object movement is like 4 dimensional spaghetti). It's an interesting read but it seems like he just wants his idea of the universe to be more literal than it is.