What makes you think that? The overwhelming majority of functions aren’t computable. The evidence suggests, if anything, that the universe is uncomputable and at best some isolatable well-measured specific phenomena can have approximations computed to some arbitrary but inexact precision.
Because if it's physically grounded then you can build a physical analogue of it.
> overwhelming majority of functions aren’t computable
By Turing machines, not by any other type of machine. As I said, if hypercomputers exist then they can solve the Halting problem, which Turing machines cannot.
Not only is there no practical way of creating such a thing, most formulations of physics preclude any possibility of making one by placing finite limits of the amount of space or time accessible to us.
(Not to mention that almost all reals are [Turing] uncomputable in their own right, but that's a more complex thing to demonstrate.)