Rayan, Rastin,
I couldn't disagree with you more as I've openly disagreed with Cristi also.
First, if you analyse carefully this his statement you quoted : "But even if we would know with what mathematical structure our world is isomorphic, it wouldn't mean we would know everything, because our knowledge can only be expressed in a finite number of axioms, and our proofs can only have finite length. Our knowledge will always be limited by G ̈odel incompleteness (G ̈odel, 1931) and Turing's noncomputability result (Turing, 1937) you could right away notice many anomalies:
1. It's not even grammatically correct ( "But even if we knew everything...it wouldn't mean... " is the correct syntax in English but Cristi is grammatically thinking in his mother tongue so I can understand and overlook the root of his error.
2. It's logically inconsistent since Gödel's results express exactly the opposite, namely, the even in mathematics there can never be a complete and self-sufficient system of knowledge grounded on a finite set of axioms, therefore mathematics is inexhaustible in itself. Chaitin, for instance, went even further to assert that mathematics as such, after Gödel, is ruled by uncertainty and randomness just like the one discovered in QM. He could be right in the sense that whenever and wherever actual infinity pops up(especially since Cantor open the way in set theory)so does uncertainty and randomness, so in a way, the so-called hidden order that science strives to discover in the Universe, seems paradoxically to be both opposed to randomness/chaos/disorder and necessary to it!...
3. Finally, it's semantically meaningless because it's a speculative and arbitrary hypothesis about an isomorphism of 'nothing concrete' with something abstract, that is, a clearly defined concept of a mathematical structure such as a topological or metric space for instance that are not only rigorously defined axiomatically.