> there are no physical observations which contradict Zuse's notion, as he wrote it, of a computable universe.

There is no model capable of simulating the universe either.

I also wonder what such an observation would have to look like. Observations per se are unique and recorded and therefore can be reconstructed via trivial computation. Which brings us to the laws of physics. You may believe that they are utterly wrong and the universe is deterministic after all, but then the burden of proof is upon you.