[User23]

This belief is widespread, but mistaken. It tries to slip in a conjecture as an axiom in the unstated leg of the enthymeme. It’s the worst sort of hand waving, but the conclusion apparently flatters the biases of those who wish to believe it such that they happily overlook the sloppiness.

Also our physical theories are only computable with an arbitrary halt thrown in at some level of accuracy deemed good enough. And there too theoretically questionable trickery like renormalization is used to reduce the problem to a tractable size.